Dissertations / Theses on the topic 'Crop improvement'

Plant biotechnology and molecular biology are now being used to complement conventional breeding programmes in most of the world's important crop species. The aim of the research described in this thesis was to improve New Zealand's horticultural crop plants through application of similar molecular techniques. A) Gene transfer systems for apple, pepino and tamarillo Tissue culture systems were developed for micropropagation and regeneration of apple (cv Royal Gala), pepino (cv El Camino) and tamarillo (selection Oratia Red). In all three species, transient expression of the gusA reporter gene was observed and kanamycin resistant callus was produced, following inoculation with the pKIWI110 binary vector in the avirulent Agrobacterium strain LBA4404. No transgenic apple shoots were obtained. However, transgenic pepino and tamarillo plants expressing the gusA reporter gene, kanamycin resistance and herbicide tolerance were successfully regenerated. PCR and Southern analysis provided molecular evidence for integration of foreign DNA into the genomes of transgenic pepino and tamarillo plants, but indicated deletions of the integrated T-DNAs had occurred with high frequency. Inheritance of the transgenic phenotypes was demonstrated in the progeny of transgenic tamarillo plants. B) Characterisation of polygalacturonase genes A kiwifruit genomic clone with homology to a tomato cDNA clone for polygalacturonase (PG) was sequenced over an 8.1 kb region. The sequence revealed a gene divided into nine exons, with 58% overall identity to the tomato PG gene at the amino acid level. Significant homology was also noted to PG genes isolated from peach, Oenothera organensis and maize, particularly in several blocks of conserved amino acids believed to encode the active site of the enzyme. Analysis of the kiwifruit PG promoter revealed three 81 bp direct repeat sequences just upstream of the kiwifruit peptide start codon. These repeats were also conserved in a second kiwifruit PC genomic clone. Characterisation of partial cDNA clones indicated that at least two mRNAs for PG were expressed in ripe kiwifruit. Southern hybridisation detected the PG gene at low copy number in the genomes of kiwifruit, two other Actinidia species, apple and pepino. PCR was used to amplify a fragment of the apple PG gene for sequence analysis. PG sequences were also used to help define the genetic origin of kiwifruit. A region of the PG gene was amplified and sequenced from four Actinidia species: kiwifruit (A. deliciosa), A. chinensis, A. eriantha and A. chrysantha. These sequences were used to produce a phylogeny using PAUP (phylogenetic analysis using parsimony). Two distinct lineages of PG genes were observed in the genomes of A. deliciosa, A. chinensis and A. eriantha. Within both these lineages, A. deliciosa sequences were quite distinct to those found in the other three Actinidia species, with the exception of a single sequence that was identical to A. chinensis. These results suggest that hexaploid kiwifruit is an allopolyploid with A. chinensis and at least one other Actinidia species as likely progenitors.

Thesis (Ph.D) -- University of Adelaide, Depts. of Plant Science and Crop Protection, 1998.
Thesis (Ph.D.)--University of Adelaide, Depts. of Plant Science and Crop Protection, 1999? Bibliographical references: leaves 112-125.

Despite of the documented impacts of the so-called green revolution, food security in the world faces new challenges in terms of population growth, increases in no-agricultural land use (urbanization), and climate change. Trends in food security show that the world community is operating within two limits of food system: (i) the quantity of food that can be produced under a given climate; and (ii) the quantity of food needed by a growing and changing population. Therefore, taking food security successfully into the future requires novel approaches to boost agricultural productivity in order to balance food supply and demand without expanding the agricultural land. To date, progress in wheat yield has been largely the result of the development of dwarf varieties through introgression of reduced height (Rht) genes. The height reductions arising from the presence of these genes increased yield by alteration of partitioning of dry matter and nitrogen in favour of the spike. However, increased partitioning through additional reductions in plant height is not likely; as comparative studies indicate that wheat yield is reduced when plants are shortened beyond a threshold, and most of the modern cultivars have reached the optimal height. Therefore, this dissertation aimed to identify the physiological attributes able to produce yield increases in the Rht genotypes with the optimal heights. Approaches based on physiological understanding of yield are necessary for developing genotypes combining high yielding potential and agronomic traits of superior adaptation, and for understanding yield limiting factors. Yet, direct measurement of physiological variables is often difficult or expensive; as an example, measuring plant water status in the field is problematic, with techniques such as psychrometry generally only being suitable for laboratory studies. Therefore, proxy such as tissue RWC may be a good alternative measure of plant water status. We aimed to address these questions with three components of experimental research :(i) proxy-based screening to increased photosynthetic rate and water use efficiency in wheat; (ii) determinants of increased HI in lines with different Rht genes (b, c) when incorporated into contrasting background wheat genomes (B, D), and the relative effect on N partitioning during grain filling; (iii) analyses of stable isotopes (δ²H, δ¹⁸O, δ¹⁵N and δ¹³C) in an agronomic perspective in alley cropping systems associated with adjacent N₂ fixing trees, in terms of hydraulic redistribution, N availability and crop yields. In this thesis, the proxy-based approach to crop selection was defined as a surrogate-based (proxy and surrogate used interchangeably) screening of cultivars for morphological, anatomical, and physiological traits of performance or crop environmental responses. The research proposed steps for conducting a proxy-based crop selection programme. A comparative screening of 23 Eps cultivars and ranking for traits of photosynthetic and water use efficiency showed the correlative relationships of SLA to An, WUEi, leaf N, Δ¹³C, Kh, leaf RWC, and IVD. Additionally, it was observed that IVD may influence WUE and Amax. It was suggested that these relationships of SLA to traits of photosynthesis possibly resulted from the association of SLA and the leaf biochemical characteristics. Attention was also given to examining the mechanistic foundations that determine the relationship between plant height and yield. The results showed the straw-shortening significantly correlated both with Amax and Kh; and SLA decreased with the level of dwarfing; and the Amax related both Kh and SLA. Therefore, it was proposed that the straw-shortening may affects Amax by exerting a controlling influence over Kh through SLA. Moreover, both the partitioning of N to spike and the flag leaf N were related to plant height and growth stage. Additionally, the increased post-anthesis partitioning of N to grain associated with high N uptake rate and high MRT of N were probably the traits behind increased NUE and NHI. The data also indicated that increased grain number per spike, kernel weight and reduced peduncle length might be the driver of the increased HI in this experiment. The test of the hypothesis that there might be practical application of the analyses of the natural abundance of stable isotopes (δ²H, δ¹⁸O, δ¹³C, and δ¹⁵N) and isotopic mixing model by IsoSource to understand plant interactions in terms of water redistribution and nitrogen transfer and uptake in agroforestry systems, indicated a consistent gradient in depletion of wheat xylem water δ²H, δ¹⁸O, and δ¹⁵N in leaf as moving further away from the tree line. The data also reflected a consistent pattern of isotopic values (δ²H, δ¹⁸O, and δ¹⁵N) in wheat in the proximity of the tree being similar to that of the tree, suggesting they were using the same source of water and N. Similarly, an isotopic mixing model data showed that the crops in the proximity of the trees accessed considerably amounts of the water and nitrogen redistributed by trees. The study also indicated the improvement in water use efficiency, chlorophyll content, grain number per spike, and grain yield for the crops nearest to the trees for a distance up to 5 m. In conclusion, selection for increased HI should shift focus from reduced plant height to include increased grain number and kernel weight, increased partitioning of N to spike, reduced peduncle length, and low SLA. Finally, the hypothesis that efflux of water and N in agroforestry system from tree roots in topsoil and influences a number of physiological functions of neighbouring crops was confirmed by isotopic and physiological data.

Sugar beet (Beta vulgaris L. subsp. vulgaris) is an economically important crop for the production of dietary sucrose. Breeding efforts towards crop improvement traditionally aim to increase sugar yield as well as in field performance. However, more recently the sugar beet pulp, a by-product of sucrose extraction, has been identified as a potential resource for additional industrial applications. Therefore breeding efforts could be directed towards the improved composition of sugar beet pulp for efficient use in these industries. Plant cell wall composition is integral to both crop performance as cell walls play a role in root growth, development and sucrose accumulation. In addition, plant cell walls make up the majority of sugar beet pulp and therefore cell wall composition influences post extraction applications. A developmental study of three Beta vulgaris varieties, utilising a monoclonal antibody directed to xylan, has allowed the visualisation of the xylem vessels within the successive cambial arrangement seen in beet roots. Importantly, a novel monoclonal antibody (LM26) directed towards phloem sieve elements has been characterised as part of this project (Torode et al., 2018). This mAb has allowed the visualisation of the relative location and abundance of phloem sieve elements in situ and how this could translate to sucrose accumulation. Monoclonal antibodies directed to several different cell wall polysaccharides were used to screen field grown commercial sugar beet (Sophia) using immunoassay techniques (Enzyme-linked immunosorbent assay (ELISA) and for the first time compared against the cell wall polysaccharide screening technique Comprehensive microarray polymer profiling (CoMPP)) on the same samples to compare the best use of these techniques. These screens indicated that sugar beet cell wall composition is modified throughout development and is influenced by environmental factors. The CoMPP technique was manipulated as a high throughput method to compare the cell wall composition of a unique population of recombinant inbred lines (RILs). Cell wall characteristics were identified which can influence the physiological properties such as sugar yield to aid the phenotyping of the varied population. From this analysis candidate lines have been selected from the RILs that have the potential to be used to direct breeding efforts towards crop improvement.

Thesis (M.S.)--Northwest Missouri State University, 2008.
The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on July 25, 2008) Includes bibliographical references.

Crop productivity is limited by a number of important constraints that need to be addressed urgently in order to avoid an imminent humanitarian crisis. My thesis provides three diverse yet converging examples of biotechnological solutions that can deliver fundamental knowledge, tools and potential products in the form of improved/enhanced crop plants. I conclude my thesis by discussing the potential of biotechnology to address the MDGs. My key conclusion is that although biotechnology can contribute positively and substantially towards many of the MDGs, political expediency and an over-burdening regulatory system threaten to prevent those needing the technology from gaining access, i.e. impoverished subsistence farmers and their families in the developing world.

During the past 36 years, the Author has contributed to the science and practice of agriculture in tropical and subtropical Australia, in the areas of crop improvement and sustainable agricultural production. These contributions were made during three phases of activity (i) through postgraduate studies at the University of Queensland (M Agr Sc, 1968-1971) and at the University of Minnesota (Ph D, 1971-1973); (ii) as a research scientist with the Commonwealth Scientific and Industrial Research Organization (1973-1994); and (iii) through leadership of the Cooperative Research Centre for Sustainable Sugar Production (CRC Sugar) and its education program, and concurrently as professor of tropical crop science at James Cook University (1994-2003). Contributions during the period 1968-1994 focussed heavily on developing a scientific understanding of the physiological basis of genotype X environment (g X e) interaction effects on the phenology, growth and yield of tropical grain legume crops. The main target crops were soybean (Glycine max L. Merr.), mungbean (Vigna radiata (L.) Wilczek) and black gram (V. mungo L. Hepper), and to a lesser extent cowpea (V. unguiculata (L.) Walp.), pigeon pea (Cajanus cajan (L.) Millspaugh) and minor pulses in the Vigna group (rice bean, adzuki bean). Particular emphasis was placed on elucidating the physiological basis of adaptation of these legumes in tropical and subtropical environments, and the implications for crop improvement. The physiological processes of main interest were phenological development, crop growth, yield and its components, seed quality and symbiotic nitrogen fixation. Environmental factors of main interest were day length, temperature, and water supply (both in excess and deficit), with some lesser focus on biotic factors such as insects and crop diseases. It was established that differential genotypic responses to photo-thermal regime contributed to variation in phenological response, with major implications for crop growth and yield potential and adaptation to the environment with respect to latitude and sowing date. These in turn interacted with agronomy and influenced optimal management. In the process, genotypic relations between rate of development and photoperiod and temperature in the field were described and quantified, as were the relations between crop duration, harvest index, biomass accumulation and seed yield. Interaction effects between varietal duration and sowing density were explained and the implications for optimal sowing density established for both irrigated and rain fed crops. Advances were made in understanding the effects of host plant physiology on nitrogen fixation. Relations between harvest index and nitrogen harvest index in different legumes and their implications for crop improvement were described. Differences in drought stress response strategy among tropical grain legumes were discovered and described. The ability of soybean to acclimate to saturated soil was described and the novel saturated soil culture system developed. Advances were made in understanding the physiology of weathering in mungbean and black gram, and genotypic differences in resistance were identified. Studies were extended beyond the cultivated germplasm to explore the natural genotypic variation for traits of agronomic and/or adaptive significance in related wild Vigna and Glycine species found in Australian and nearby islands. In the process, a unique collection of more than 400 native legume accessions was assembled and described, and seed committed to long-term storage in a national germplasm collection. Cross-fertility between cultivated and wild Vigna species was explored and the inheritance of key traits documented. The research findings on the tropical grain legumes were synthesised into a more coherent generalised understanding of their physiology, and the potential application of physiological knowledge in crop improvement was explored using the tropical grain legumes as a model. The then-novel idea was advanced that the most effective use of physiology in crop improvement was in developing a biological understanding of g X e to augment the statistical models used by breeders. It was also argued that crop improvement should concurrently involve breeding better adapted crop varieties, and developing agronomic practices that best enabled the genetic potential of crop varieties to be exploited. Among the areas where these concepts were applied was the novel concept of using the long-juvenile gene to ‘convert’ high-yielding, lodging resistant, temperate soybean germplasm to tropical adaptation. During the period 1994-2003, scientific contributions focussed on improving the sustainability of sugar production systems in northern Australia, with emphasis on three broad program areas: enhancing crop productivity, sustaining soil and water resources, and protecting the wider environment. Contributions included a leadership role in the development in collaboration with others of novel approaches for fostering team-based, multi-disciplinary research and postgraduate research training on complex sustainability issues. At a personal research level, the focus was on the application in the context of student training projects of physiological concepts to improve sugarcane productivity in the wet tropics. Advances were made in identifying the effects of harvest timing and other management practices on cane yield and CCS, in quantifying the effects of lodging on productivity and in elucidating environmental stimuli of suckering. The improved scientific understanding of soybean and mungbean provided the basis for undertaking, in collaboration with others, improvement programs on these legumes for northern Australia, and in Thailand and Vietnam. Recommendations for agronomic management of these crops were promulgated in collaboration with industry, and three cultivars (1 tropical soybean, 1 mungbean and 1 black gram) were released for commercial production. These outputs contributed to the establishment and subsequent development of soybean and mungbean cropping in northern Australia. In the case of sugar cane, the strategic research on low productivity in the wet tropics focussed attention on lodging and suckering as key constraints in the wet tropics, while the research on sustainable sugar production more generally has helped map the path for a sustainable future for the sugar industry. In the research on both grain legumes and sugar cane, innovation was demonstrated in the contributions that were made, and in the processes whereby they were accomplished. The research on new grain legume crops for Australian agriculture was by definition novel, as was the early focus on using physiological understanding of these species to develop biological explanations for g X e. The use of contestable industry research funds to support postgraduate research training pre-dated the formal introduction of postgraduate research training scholarships by the rural industry research and development committees, while the extensive supervision of postgraduate students was then unprecedented for a CSIRO scientist. Also demonstrated was leadership in fostering team-based, multi-disciplinary collaborations, often in the context of joint projects supported by national and international agencies, and in developing countries where the tropical crops of interest were widely grown. The research was also usually undertaken in close collaboration with relevant industry interests, which facilitated uptake of the outputs. At the time, these collaborations, which included students, colleagues and industry end-users, initially with funding support from industry and later from the Australian Centre for International Agricultural Research (ACIAR) and then the Cooperative Research Centre (CRC) Program, were at the forefront of the development of team-based R&D models in Australia. The synergies from these collaborations with colleagues, students and industry stakeholders enhanced the contributions that were able to be made. They also enabled initial discoveries to be explored and elaborated in ways that otherwise would not have been possible.

Canola fuels a multi-billion dollar industry in Canada. It is a Canadian trademarked name of specific cultivars derived from specific Brassicaceae plants. Cis-NATs are natural antisense transcripts that overlap a gene and are not translated into proteins. Instead, they silence their parent gene's expression through various mechanisms. Their role in humans is well established, but their role in plants is relatively obscure. The goal of this thesis project is to analyze the conservation of cis-NATs across 8 different Brassicaceae genera (9 species). This is useful for picking up targets for crop improvement in canola. Conservation was studied across the 9 species, then across two subgroups of 4 and 2 species, respectively; cis-NATs simultaneously exhibiting conservation in all three scenarios were selected. A total of 34 potential candidates were identified. The study also suggests that the type of a cis-NAT might also affect its conservation. The presented methodology is a powerful pre-screening strategy to direct experimental efforts. It can be used with genes and other transcribed non-coding DNA.
Le canola est à la base d'une industrie canadienne de plusieurs milliards de dollars. En fait, le mot canola est un acronyme canadien incluant certaines plantes dérivées d'espèces de la famille des Brassicaceae. Les cis-NATs sont des molécules d'ARN qui ne sont pas traduites en protéines. Elles réduisent plutôt l'expression des gènes qu'elles superposent à travers différents mécanismes. Leur rôle chez les humains est bien établit, mais ce n'est pas le cas chez les plantes. Le but de cette thèse est d'identifier des cis-NATs qui sont conservés à travers 8 genres différents (9 espèces) de la famille des Brassicaceae. Cela est pratique pour identifier des candidats pouvant être utilisés pour une application agronomique. La conservation a été étudiée à travers les 9 espèces, puis à travers deux sous-groupes de 4 et 2 espèces, respectivement. Les cis-NATs qui démontraient une conservation à travers 9, 4, et 2 espèces simultanément ont été sélectionnés. 34 candidats ont été identifiés. Le projet de recherche suggère aussi que le type de cis-NAT peut potentiellement influencer sa conservation. La méthode présentée est une stratégie de recherche préalable et très efficace pour diriger les efforts expérimentaux. Elle peut être aussi utilisée avec des gènes ou n'importe quel autre élément génétique non codant qui est transcrit.

Biodiversity is expected to be an assurance for agroecosystem resilience because it seems fundamental to preserve basic ecosystem services (ES). To examine in depth these topics, the present research aims: a) to evaluate, in real farms, the environmental sustainability by measuring the efficiency of some key ES in agroecosystems with different management; b) to search for relationships among biodiversity groups and ES and c) to explore the existence of correlations between different bioindication methodologies. The basic hypothesis is that a high efficiency of the ES can improve the environmental sustainability of agroecosystems. ES were studied by using several bioindicators associated to the functional biodiversity, which guarantees these useful services to crops. The chosen bioindicators, representing the principal trophic levels, were appropriate tools to investigate the complexity of food web in the crop field. The chosen bioindicators providing basic ES were: 1. Earthworms, soil structure drivers, responsible for air and water circulation and drainage, for organic matter (OM) decomposition and for cast enriching activity; 2. Mesofauna (including mites and springtails), which comprises mainly detritivores and small preys and predators; 3. Soil bacteria and fungi, promoters of OM decomposition, nutrient cycles, soil enzymatic activities and improvement of soil-root-water relationships; 4. Key Predators (including carabids) and parasitoids, natural control agents for crop pest outbreaks; 5. Crop Weeds and field margin vegetation, important reporters of soil conditions, can act as shelters for overwintering, provide alternative food sources for useful fauna and can attract pollinators in the field area. The research was carried out during 2012-2013 in five organic-biodynamic and five conventional horticultural fields in the Venice and Treviso provinces. The methodologies adopted to sample biodiversity of these bioindicators were: 30x30x20cm soil core hand sorting with irritant mustard powder water suspension for earthworms; Berlese-Tullgren extractor for mesofauna; Automated Ribosomal Intergenic Spacer Analysis and 16S and ITS sequencing performed in a 454 system (Roche) for overall communities of soil bacteria and fungi, PCR and qRT-PCR with specific primers for Arbuscular Mycorrhizal Fungi (AMF); Visual control on the aboveground part of crop for phytophagous agent and predator communities; Indoor breeding for parasitoid communities; Random nested data collection for weed communities. After sampling with the aim to know the biodiversity guilds, other innovative techniques were exploited to measure environmental quality. Regarding the component of soil mesofauna, the QBS-ar index was applied to assess the status of soil alteration but not performable by a taxonomically inexperienced operator. In order to analyse earthworms, the new QBS-e index based on earthworm ecological categories, similar to QBS-ar but easier to use also by non-experts, was successfully applied. To measure microbiological activity and biomass, soil respiration rate assay, Fluorescein Diacetate hydrolysis test, dsDNA quantification together with key soil enzymatic activities were carried out along with probes with Fertimeters , simple devices made of silk and cotton yarns working as reporters of organic matter degradation. In order to assess the natural pest control, besides the quantification of predator presence in the field, the parasitization and hyperparasitization percentages regarding one of the most problematic cabbage pest (Plutella xylostella) were calculated. To quantify the extent of pollinator and useful fauna attraction of weed communities, an Entomophily Index (E.I.) was adopted that takes into account the presence and abundance of insect-pollinated species. Some conclusive remarks were: 1.Taxa composition of a bioindicator group does not always change according to different agroecosystem managements. There seem to be more sensitive bioindicators to management practices, such as predators and parasitoids (belonging to higher trophic levels), than others, such as phytophagous agents and weeds. 2.Biodiversity, simply described with classical diversity indexes found in literature, seemed not to be associated to the ES efficiency, probably because the link has to be searched in the complexity of interactions among all biodiversity groups. 3.Agroecosystems managed in an organic-biodynamic way demonstrated to have more efficient ES (almost all among the ones measured) both in the aboveground and in the epigeal sectors and therefore this management system can be defined as more sustainable from environmental point of view. 4.Finally a great quantity of correlations emerged between all analysed indicators (biotic and functional): these could be very useful to better planning future programs of monitoring of agroecosystem conditions
La biodiversità è ritenuta essere una sorta di garanzia per la resilienza dell’agroecosistema in quanto sembra fondamentale per preservare basilari servizi ecosistemici (SE). Al fine di approfondire queste tematiche, questo lavoro si propone di: a) valutare, in aziende reali, la sostenibilità ambientale misurando l’efficienza di alcuni SE chiave in agroecosistemi a differente gestione; b) cercare relazioni fra i gruppi di biodiversità studiati e i SE e c) esplorare l’esistenza di correlazioni fra le differenti metodologie di analisi considerate. L’ipotesi di base è che una elevata efficienza dei SE può migliorare la sostenibilità ambientale dell’agroecosistema. I SE sono stati studiati utilizzando numerosi bioindicatori associati alla biodiversità funzionale, che è in grado di garantire alla coltura questi utili servizi. I bioindicatori scelti, appartenenti ai principali livelli trofici, sono stati strumenti appropriati per indagare la complessità della rete trofica nel campo coltivato. I bioindicatori scelti, che provvedono a SE fondamentali, sono stati: 1. Lombrichi, promotori della struttura del suolo, fra i maggiori responsabili della circolazione di aria e acqua e del drenaggio, della decomposizione della sostanza organica e della attività di arricchimento del suolo in nutrienti dovuta agli escrementi; 2. Mesofauna (come acari e collemboli), che comprende principalmente detritivori e piccole prede e predatori; 3. Batteri e funghi del suolo, promotori della degradazione della sostanza organica, dei cicli biogeochimici dei nutrienti, delle attività enzimatiche del suolo e del miglioramento delle relazioni suolo-radici-acqua; 4. Predatori (compresi i carabidi) e parassitoidi, agenti di controllo naturale delle pullulazioni di fitofagi; 5. Malerbe del campo coltivato e Piante spontanee di margine, importanti reporter delle condizioni del suolo, che possono fungere da rifugi per lo svernamento, possono fornire fonti alternative di cibo per la fauna utile e inoltre possono attrarre impollinatori nell’area del campo. La ricerca è stata sviluppata negli anni 2012-2013 in cinque campi biologici-biodinamici e cinque campi convenzionali coltivati ad orticole siti nelle province di Venezia e Treviso. Le metodologie per campionare la biodiversità di questi bioindicatori sono state le seguenti: hand sorting su una zolla di 30x30x20cm con precedente versamento di sospensione acquosa di polvere di senape, che funge da irritante per i lombrichi (in particolare per i profondi scavatori); l’estrazione con l’apparato Berlese-Tullgren per la mesofauna; la tecnica Automated Ribosomal Intergenic Spacer Analysis e il sequenziamento del gene 16S e ITS eseguito con il sistema 454 (Roche) per lo studio completo delle comunità di batteri e funghi del suolo, la tecnica PCR e real time-PCR con primer specifici per i funghi micorrizici (AMF); il controllo visivo sulla parte epigea della pianta coltivata per l’indagine della presenza di fitofagi e predatori; il successivo allevamento in laboratorio per indagare le comunità di parassitoidi; la raccolta raggruppata e casuale di dati sulle specie e le relative abbondanze di piante erbacee spontanee per esaminarne le comunità nell’area del campo e del margine erboso di capezzagna. Dopo aver campionato con lo scopo di conoscere i principali gruppi di biodiversità, si è proceduto applicando delle tecniche innovative e speditive utili per misurare la qualità dell’agroecosistema. Considerando la componente della mesofauna del suolo, è stato applicato l’indice QBS-ar per valutare lo stato di alterazione del suolo ma non applicabile da un operatore non esperto in tassonomia. Al fine di analizzare la comunità di lombrichi, è stato applicato il nuovo indice QBS-e basato sulle loro categorie ecologiche, simile al QBS-ar ma più facile da usare anche da non esperti. Per misurare l’attività e la biomassa microbica, il test di valutazione del tasso di respirazione del suolo, il test di idrolisi della fluoresceina diacetato, la quantificazione del dsDNA unitamente a saggi sulle attività di enzimi chiave del suolo sono stati condotti insieme al test con il fertimetro , un semplice strumento costituito da fili di seta e cotone che fungono da reporter della degradazione della sostanza organica. Al fine di valutare il controllo biologico naturale dei parassiti delle colture, oltre alla quantificazione dei predatori presenti sul campo, sono state calcolate anche le percentuali di parassitizzazione e iperparassitizzazione relative ad uno fra i più problematici parassiti del cavolfiore (Plutella xylostella). Per quantificare l’entità dell’attrazione di impollinatori e fauna utile svolta dalla comunità delle piante erbacee spontanee, un indice di entomofilia (E.I.), che prende in considerazione la presenza e l’abbondanza di specie entomofile, è stato applicato. Alcune considerazioni conclusive sono state: 1. La composizione in taxa di un gruppo di bioindicatori non sempre cambia in base a differenti gestioni dell’agroecosistema. Sembrano esserci bioindicatori più sensibili alle pratiche di gestione, come ad esempio i predatori e i parassitoidi (appartenenti a livelli trofici superiori), rispetto ad altri, come fitofagi e malerbe. 2. Gli agroecosistemi a gestione biologico-biodinamica hanno dimostrato di avere SE più efficienti (quasi tutti fra quelli misurati) sia nel settore ipogeo che in quello epigeo e perciò questo tipo di gestione si può definire più sostenibile dal punto di vista ambientale. 3. La biodiversità, descritta semplicemente con i classici indici di biodiversità che si trovano in letteratura, non sembra essere associata all’efficienza dei SE, probabilmente perché il collegamento fra questi due fattori deve essere cercato nella complessità delle interazioni fra tutti i gruppi di biodiversità considerati. 4. Infine, una grande quantità di correlazioni fra tutti gli indicatori analizzati (biotici e funzionali) è emersa: tali correlazioni potrebbero essere molto utili per pianificare meglio futuri programmi di monitoraggio delle condizioni degli agroecosistemi

L'ordi (Hordeum vulgäre L.) és un cereal de zones temperades conreat extensament en
climes mediterranis. Es desenvolupa favorablement en àrees de pluviometria mitjana anual
superior a 250 mm. Durant les darreres dècades, els increments en rendiment deguts a activitats
de millora genètica han estat poc importants a causa, probablement, de la limitació que la sequera
i altres estressos abiòtics exerceixen sobre el creixement. Futurs increments poden veure's
accelerats per un millor coneixement dels processos que controlen el creixement i
desenvolupament i que limiten la product! vi tat dels genotips en situacions de manca d'aigua. Dins
d'aquest contexte, les activitats d'investigació en fisiologia vegetal haurien de tenir un fort
impacte, en un futur proper, en l'increment de l'eficiència dels programes de millora tradicionals.
Aquesta tesi pretén ampliar el coneixement actual d'aquells factors que redueixen el creixement,
la productivitat i la qualitat de l'ordi en ambients mediterranis. Amb aquesta finalitat, s'han
avaluat en assajos localitzats a la província de Lleida (nordest d'Espanya) i, ocasionalment, a les
províncies de Navarra (nord d'Espanya) i Valladolid (centre d'Espanya), un conjunt de deu
genotips d'ordi (incloent-hi dos i sis carreres) que difereixen en adaptació a ambients semiàrids.
Inicialment, un conjunt de tres genotips moderns i altament productius (Barberousse,
Orria i Plaisant) va ésser utilitzat per examinar l'efecte que una reducció de l'embomal
reproductiu (nombre de grans per espiga) provocava sobre el pes i el creixement del gra,
l'acumulació de carbohidrats i el transport de nitrogen en condicions semiàrides (Capítols I i II).
Els increments en pes de gra obtinguts en resposta a una reducció del 50% de l'embornal van ser
progressivament superiors en aquells ambients amb grans testimoni de menor pes. Pel contrari,
el nitrogen es va acumular uniformement en tots els ambients en resposta a una reducció de
l'embornal. Aquests resultats suggereixen que el rendiment final es troba fortament limitat, en
ambients productivament pobres, per la disponibilitat de carbohidrats durant l'omplenat del gra,
en tant que l'acumulació de proteïnes en el gra sembla independent de les condicions ambientals
en que té lloc l'omplenat del gra. El grau de limitació exercit per la font es va manifestar més
elevat en els grans situats en espigúeles laterals de l'espiga, amb independència de la
disponibilitat d'assimilats per l'omplenat del gra. Aquest desavantatge dels grans laterals de
l'espiga es va poder atribuir principalment a taxes d'acumulació de matèria seca inferiors durant
l'omplenat.
La influència d'estressos abiòtics com ara la sequera o les altes temperatures en el procés
d'omplenat dels grans es va examinar en detall utilitzant el conjunt dels deu genotips assajats en
dotze ambients (Capítols III i IV). L'objectiu final va consistir a detectar variabilitat genètica així
com determinar possibles mecanismes morfofisiològics de tolerància als esmentats estressos. Els
possibles factors causants d'interacció genotip-ambient (G*E) en el pes del gra, tasa i duració
d'omplenat es van estudiar mitjançant l'ús de models estadístics biadditius. Es van detectar
sensibilitats genotípiques diferencials en tolerància a sequera i a elevades temperatures de postantesi
pel pes final del gra, que varen atribuir-se parcialment a diferències entre els grups d'ordis
de dos i sis carreres. La presència de GxE per a la taxa d'omplenat es va explicar per l'efecte
conjunt de variables climàtiques de pre-antesi, la qual cosa va suggerir que les diferències
genotípiques podrien ser degudes parcialment a diferències en el balanç font/embornal entre ordis
de dos i sis carreres en antesi. L'existència de GXE per a la duració d'omplenat va poder-se
atribuir principalment a diferències en data d'antesi entre genotips, indicant l'existència d'una
estratègia d'escapament causant d'un allargament del période d'omplenat d'alguns genotips a
finals del cicle de cultiu.
La relació entre rendiment i discriminació isotòpica del carboni (A) en grans va avaluar-se
extensament en un grup de 22 ambients (Capítol VI), i també va examinar-se la possibilitat
d'utilització de la concentració de cendres en teixits aeris com a substitut de A (Capítol VII).
L'expressió genotipica del rendiment va estar condicionada per l'ambient d'una forma més
important que la de A. L'existència de GxE pel rendiment va suggerir la presència d'una
interacció qualitativa amb un punt de creuament aproximat situat en productivitats mitjanes
inferiors a 3 t ha"1. Pel contrari, la classificació de genotips per a A no va variar substancialment
amb l'ambient. En general, aquells genotips amb valors baixos de A i, per tant, amb elevades
eficiències de transpiració, van ésser superiors en ambients poc productius (ambients per sota de
3 t ha"1), en tant que valors genotípics de A elevats van mostrar-se com avantatjosos en ambients
de rendiment mig i alt. És probable que, quan la sequera sigui moderada, un important embornal
reproductiu forci la planta a incrementar la seva conductancia estomàtica i, com a conseqüència,
l'aigua total utilitzada. Aquest fenomen probablement capgira la relació negativa esperada entre
A i biomassa o rendiment quan la disponibilitat d'aigua és factor limitant. Per altra banda, la
concentració mineral en grans va trobar-se relacionada freqüentment i de forma negativa amb A,
en tant que no va trobar-se relació entre la concentració mineral en palla i A. Aquests resultats
suggereixen que l'acumulació mineral en teixits aeris mostrejats a finals del cicle de cultiu és
independent de l'eficiència de transpiració durant l'omplenat del gra. La concentració de cendres
en grans podria emprar-se com a criteri de selecció complementari a A en ambient semiàrids, si
bé es fa necessari un coneixement fisiologie més profund dels mecanismes que afecten
l'acumulació de minerals en el gra.
La sequera esdevé el principal factor limitant del creixement i la productivitat de l'ordi
en els secans semiàrids mediterranis. En el present estudi, les diferències en productivitat en un
conjunt de 22 ambients van poder atribuir-se, en gran part, a diferències paral·leles en
disponibilitat hídrica des de sembra fins a antesi, période en el qual es determina el nombre de
grans per m2. La presència d'una interacció GXE de tipus qualitatiu pel rendiment, així com les
relacions fluctuants entre rendiment i A, depenent de la intensitat de l'estrès hídric, suggereixen
que la tolerància a la sequera i l'elevat potencial de rendiment son conceptes antagònics en ordi.
La cebada (Hordeum vulgäre L.) es un cereal de zonas templadas ampliamente cultivado
en climas mediterráneos. Se desarrolla favorablemente en zonas de pluviometría media anual
superior a 250 mm. Durante las últimas décadas, los incrementos en rendimiento debidos a
actividades de mejora genética han sido poco importantes probablemente a causa de la limitación
que la sequía y otros estreses abióticos ejercen sobre el crecimiento. Futuros incrementos pueden
verse acelerados por un mejor conocimiento de los procesos que controlan el crecimiento y
desarrollo y que limitan la productividad de los genotipos en situaciones caracterizadas por la
falta de agua. En este contexto, las actividades de investigación en fisiología vegetal deberían
tener un fuerte impacto, ya en un futuro próximo, en el incremento de la eficiencia de los
programas de mejora tradicionales. La presente tesis pretende ampliar el conocimiento actual de
aquellos factores que reducen el crecimiento, la productividad y la calidad de la cebada en
ambientes mediterráneos. Con este fin se ha evaluado en ensayos situados en la provincia de
Lérida (nordeste de España) y, ocasionalmente, en las provincias de Navarra (norte de España)
y Valladolid (centro de España), un conjunto de diez genotipos de cebada (incluyendo dos y seis
carreras) que difieren en adaptación a ambientes semiáridos.
Inicialmente, un conjunto de tres genotipos modernos y altamente productivos
(Barberousse, Orria y Plaisant) fue utilizado para examinar el efecto que una reducción del
sumidero reproductivo (número de granos por espiga) provocaba sobre el peso y el crecimiento
del grano, la acumulación de carbohidratos y el transporte de nitrógeno en condiciones semiáridas
(Capítulos I y II). Los incrementos en peso del grano obtenidos en respuesta a una reducción del
sumidero del 50% fueron progresivamente superiores en aquellos ambientes con granos testigo
de menor peso. Por el contrario, el nitrógeno se acumuló uniformemente en todos los ambientes
en respuesta a una reducción del sumidero. Estos resultados sugieren que el rendimiento final se
encuentra fuertemente limitado, en ambientes productivamente pobres, por la disponibilidad de
carbohidratos durante el llenado del grano, mientras que la acumulación de proteínas en el grano
parece independiente de las condiciones ambientales en las que el llenado del grano tiene lugar.
El grado de limitación ejercido por la fuente fue más elevado para los granos situados en
espiguillas laterales de la espiga, con independencia de la disponibilidad de asimilados durante
el llenado del grano. Esta desventaja de los granos laterales de la espiga pudo atribuirse
principalmente a tasas inferiores de acumulación de materia seca durante el llenado.
La influencia de estreses abióticos tales como la sequía o las altas temperaturas en el
proceso de llenado de los granos se examinó en detalle utilizando el conjunto de los diez
genotipos ensayados en doce ambientes (Capítulos III y IV). El objetivo final perseguido
consistió en detectar variabilidad genética así como en determinar posibles mecanismos
morfofisiológicos de tolerancia a dichos estreses. Los posibles factores causantes de interacción
genotipo-ambiente (G*E) en el peso del grano, la tasa y la duraoión de llenado se estudiaron
mediante el uso de modelos estadísticos biaditivos. Se detectaron sensibilidades genotípicas
diferenciales en la tolerancia a la sequía y a las elevadas temperaturas de post-antesis para el peso
final del grano, que se atribuyeron parcialmente a diferencias entre los grupos de cebadas de dos
y seis carreras. La presencia de G*E para la tasa de llenado se explicó por el efecto conjunto de
variables climáticas de pre-antesis, lo que sugirió que las diferencias genotípicas pudieran deberse
parcialmente a diferencias en el balance fuente/sumidero entre cebadas de dos y seis carreras en
antesis. La existencia de G*E para la duración del llenado pudo atribuirse principalmente a
diferencias en fecha de antesis entre genotipos, indicando la existencia de cierta estrategia de
escape causante de un alargamiento del periodo de llenado de algunos genotipos al final del ciclo
de cultivo.
La relación entre rendimiento y discriminación isotópica del carbono (A) en granos se
evaluó extensamente en un grupo de 22 ambientes (Capítulo V), y también se examinó la
posibilidad de utilizar la concentración de cenizas en tejidos aéreos como substituto de A
(Capítulo VI). La expresión genotipica del rendimiento fue condicionada por el ambiente de una
forma más acusada que la de A. La existencia de GXE para el rendimiento sugirió la presencia
de una interacción cualitativa cuyo punto de cruce cabría situarlo aproximadamente en
productividades medias inferiores a 3 t ha"1. Por el contrario, la clasificación de genotipos para
A no cambió substancialmente con el ambiente. En general, aquellos genotipos con bajos valores
de A y, por tanto, con elevadas eficiencias de transpiración, fueron superiores en ambientes poco
productivos (ambientes por debajo de 3 t ha"1), mientras que valores genotípicos de A elevados
se revelaron como ventajosos en ambientes de rendimientos medios y altos. Es probable que,
cuando la sequía es moderada, un importante sumidero reproductivo, típico de cultivares
modernos, fuerce la planta a incrementar su conductancia estomática y, en consecuencia, el agua
total utilizada. Este fenómeno probablemente invierte la relación negativa esperada entre A y
biomasa o rendimiento cuando la disponibilidad de agua es un factor limitante. Por otra parte,
XVll
la concentración mineral en granos estuvo relacionada frecuentemente y de forma negativa con
A, mientras que no se encontró relación entre la concentración mineral en paja y A. Estos
resultados sugieren que la acumulación mineral en tejidos aéreos muestreados al final del ciclo
de cultivo es independiente de la eficiencia de transpiración durante el llenado del grano. La
concentración de cenizas en granos podría utilizarse como criterio de selección complementario
a A en ambientes semiáridos, si bien es necesario un conocimiento fisiológico más profundo de
los mecanismos que afectan a la acumulación de minerales en el grano.
La sequía representa el principal factor limitante del crecimiento y la productividad de la
cebada en los secanos semiáridos mediterráneos. En el presente estudio, las diferencias en
productividad en un conjunto de 22 ambientes pudieron atribuirse en gran medida a diferencias
paralelas en disponibilidad hídrica desde siembra hasta antesis, período en el cual se determina
el número de granos por m2. La presencia de una interacción G*E de tipo cualitativo para el
rendimiento, así como las relaciones fluctuantes entre rendimiento y A, dependiendo de la
intensidad del estrés hídrico, sugieren que la tolerancia a la sequía y el elevado potencial de
rendimiento son conceptos antagónicos en cebada.
Barley (Hordeum vulgäre L.) is an important temperate cereal extensively cultivated in
Mediterranean climates. It can be grown successfully where the average annual rainfall exceeds
250 mm. Yield improvement for Mediterranean areas during the last decades has been slow
probably due to the limitation that drought and other abiotic stresses exert on plant growth. Future
increases in productivity may be accelerated by a better understanding of processes that control
growth and development and limit genotypic performance of barley provided water is scarce.
Thus, physiological research should have a considerable impact in the near future in increasing
the efficiency of traditional breeding programs. This thesis focusses on widening current
physiological knowledge of factors that curtail growth, productivity and quality of barley in
Mediterranean environments. To that end, a set often genetically diverse barley cultivare, which
includes two- and six-rowed types differing in adaptation to semiarid environments, has been
extensively evaluated in rainfed environments located in the province of Lleida (Northeastern
Spain) and, occasionally, in the provinces of Navarra (Northern Spain) and Valladolid (Central
Spain).
A subgroup of three high yielding, modern six-rowed genotypes (Barberousse, Orria and
Plaisant) was used initially to examine the effect of a decrease in the reproductive sink (i.e.,
number of grains per spike) on individual grain weight and growth, carbohydrate accumulation
and N uptake under semiarid conditions (Chapters I and II). Grain weight increases in response
to a 50% sink-reduction were progressively greater in environments with smaller control grains.
On the contrary, N accumulated uniformly across environments in response to sink manipulation.
These results suggest that grain yield is largely limited by carbohydrate supply (i.e., source
limited) during grain filling in poor rainfed environments, whereas protein accumulation into
growing grains seems independent of the environmental conditions in which grain filling
develops. The degree of such limitation to grain growth was consistently higher for those grains
placed in lateral spikelets of the barley ear, irrespective of the availability of assimilates for grain
filling. Such disadvantage of lateral grains could be ascribed mainly to lower dry matter
accumulation rates during grain filling.
The influence of abiotic stresses such as drought or high temperature in the context of the
grain filling process was further examined for the complete set often genotypes grown in 12
environments (Chapters III and IV). The final objective was to detect genetic variability and to
determine possible morphophysiological mechanisms for tolerance to these abiotic constraints.
Possible factors underlying genotype by environment interaction (GxE) for individual grain
weight (IGW), grain filling rate (GFR) and grain filling duration (GFD) were explored by means
of biadditive models. Differential genotypic sensitivities for IGW were found with respect to
post-anthesis drought and elevated temperatures, which could be partially attributed to the
difference between two- and six-rowed barleys. GXE for GFR could be partially explained by the
joint effect of pre-anthesis climatic variables, suggesting that variation in genotypic behaviour
for this trait may be caused by differences in source/sink balance between two- and six-rowed
genotypes at anthesis. In addition, GXE for GFD seemed to be driven mainly by differences in
anthesis date among genotypes, indicating the existence of an escape strategy lengthening the
grain filling period of selected culti vare at the end of the crop cycle.
The relationship between grain yield and carbon isotope discrimination (A) of mature
grains was thoroughly evaluated in a large set of 22 environments (Chapter V), and the feasibility
of using ash concentration in aboveground tissues as a surrogate of A explored (Chapter VI). The
genotypic expression for grain yield was considerably more affected by the environment than that
for A. GXE for grain yield suggested the existence of a crossover point at below 31 ha"1, whereas
genotypic ranking for A did not changed substantially across environments. Overall, genotypes
with lower A and, thus, with higher transpiration efficiency (TE), performed better in lowyielding
environments, i.e., those below the crossover point, while a high genotypic A was
advantageous in medium and high-yielding environments. It may be possible that, under
moderate drought, a large reproductive sink (typical of modern cultivars) force the plant to
increase its stomatal conductance and, consequently, its total water use. This phenomenon
probably overrides the expected negative relation between A and biomass or yield when water
is limiting. On the other hand, mineral concentration in mature grains was often negatively related
to A, and mineral accumulation in vegetative tissues was unrelated to A. Both results suggest that
mineral accumulation in aboveground tissues, sampled at maturity, is independent of the plant
TE during grain filling. Ash concentration in mature grains could be used as a complementary
criterion to A in semiarid environments, though a more accurate physiological understanding of
the mechanisms underlying mineral accumulation in grains is still needed.
Drought arises as the most limiting factor to barley growth and productivity in rainfed
Mediterranean environments. In the present study, differences in productivity in a set of 22
environments could be attributed largely to concomitant differences in water availability for
growth from sowing to anthesis, a period in which the number of grains m"2 is determined.
Presence of a crossover G*E interaction for grain yield, as well as changing relationships between
productivity and A depending on the intensity of water stress, suggest that drought tolerance and
yield potential are rather antagonistic concepts in barley.

Doctor of Philosophy
Genetics Interdepartmental Program - Plant Pathology
Jesse A. Poland
A major challenge for 21st century plant geneticists is to predict plant performance based on genetic information. This is a daunting challenge, especially when there are thousands of genes that control complex traits as well as the extreme variation that results from the environment where plants are grown. Rapid advances in technology are assisting in overcoming the obstacle of connecting the genotype to phenotype. Next generation sequencing has provided a wealth of genomic information resulting in numerous completely sequenced genomes and the ability to quickly genotype thousands of individuals. The ability to pair the dense genotypic data with phenotypic data, the observed plant performance, will culminate in successfully predicting cultivar performance. While genomics has advanced rapidly, phenomics, the science and ability to measure plant phenotypes, has slowly progressed, resulting in an imbalance of genotypic to phenotypic data. The disproportion of high-throughput phenotyping (HTP) data is a bottleneck to many genetic and association mapping studies as well as genomic selection (GS). To alleviate the phenomics bottleneck, an affordable and portable phenotyping platform, Phenocart, was developed and evaluated. The Phenocart was capable of taking multiple types of georeferenced measurements including normalized difference vegetation index and canopy temperature, throughout the growing season. The Phenocart performed as well as existing manual measurements while increasing the amount of data exponentially. The deluge of phenotypic data offered opportunities to evaluate lines at specific time points, as well as combining data throughout the season to assess for genotypic differences. Finally in an effort to predict crop performance, the phenotypic data was used in GS models. The models combined molecular marker data from genotyping-by-sequencing with high-throughput phenotyping for plant phenotypic characterization. Utilizing HTP data, rather than just the often measured yield, increased the accuracy of GS models. Achieving the goal of connecting genotype to phenotype has direct impact on plant breeding by allowing selection of higher yielding crops as well as selecting crops that are adapted to local environments. This will allow for a faster rate of improvement in crops, which is imperative to meet the growing global population demand for plant products.

This thesis considers Participatory Crop Improvement (PCI) methodologies and examines the reasons behind their continued contestation and limited mainstreaming in conventional modes of crop improvement research within National Agricultural Research Systems (NARS). In particular, it traces the experiences of a long-established research network with over 20 years of experience in developing and implementing PCI methods across South Asia, and specifically considers its engagement with the Indian NARS and associated state-level agricultural research systems. In order to address the issues surrounding PCI institutionalisation processes, a novel conceptual framework was derived from a synthesis of the literatures on Strategic Niche Management (SNM) and Learning-based Development Approaches (LBDA) to analyse the socio-technical processes and structures which constitute the PCI ‘niche' and NARS ‘regime'. In examining the niche and regime according to their socio-technical characteristics, the framework provides explanatory power for understanding the nature of their interactions and the opportunities and barriers that exist with respect to the translation of lessons and ideas between niche and regime organisations. The research shows that in trying to institutionalise PCI methods and principles within NARS in the Indian context, PCI proponents have encountered a number of constraints related to the rigid and hierarchical structure of the regime organisations; the contractual mode of most conventional research, which inhibits collaboration with a wider group of stakeholders; and the time-limited nature of PCI projects themselves, which limits investment and hinders scaling up of the innovations. It also reveals that while the niche projects may be able to induce a ‘weak' form of PCI institutionalisation within the Indian NARS by helping to alter their institutional culture to be more supportive of participatory plant breeding approaches and future collaboration with PCI researchers, a ‘strong' form of PCI institutionalisation, in which NARS organisations adopt participatory methodologies to address all their crop improvement agenda, is likely to remain outside of the capacity of PCI development projects to deliver.

This thesis presents an investigation of two production functions (a non-linear-in-parameters and a generalized polynomial) in order to determine which function most appropriately represents the observed relationships of the components of ICM technology. Four spring barley and one spring wheat datasets were assembled from ICM field trials conducted in the Montreal region (1987-89).
A quadratic and a Mitscherlich-Baule equation were fitted to the (five) datasets and compared with respect to a number of measures of goodness of fit. One dataset was chosen for generating and graphing a three-dimensional response surface, based on the fitted equations of that dataset. The two surfaces were compared in light of expectations regarding the two equations.
The fitted equations of three of the five datasets did not produce noteworthy results. The other two datasets provided mixed results. The response surfaces provided outcomes that were contrary to prior expectations. In general graphing the response surfaces offered limited additional insight. Ultimately, this project may have been hampered by the experimental design of the field trials, those designs being oriented to results of agronomic rather than economic significance.

In Libya salinization of land and ground water is a key problem. A. saligna is one species that offers potential for growth under these conditions. Experiments were undertaken to accelerate the germination of Acacia seeds, and various pre-treatment methods were assayed. Boiling water treatment, mechanical scarification and acid improved germination and germination rate. Sowing A. saligna seeds at 30 mm depth gave greatest seedling growth from large and medium seeds whereas 20 mm was more suitable for small seeds. This study aimed to improve the establishment of Acacia saligna irrigated with saline water, plants were grown for seven weeks under greenhouse or field conditions in (Libya) either sand or soil salinized with varying applications of NaCl. Irrigation with NaCl significantly decreased plant survival and growth and concentration of Ca, Na, K, Fe and P ions in plants with 0.5 M or 1.0 M NaCl. The experiments were repeated using a naturally occurring soil amendment called ‘Zander’. Seeds of A. saligna were grown for seven weeks in both greenhouse and field trials as before but with the addition of Zander and NaCl. Zander improved plant survival and growth with salinity and increased the elements in plants (Ca, Na, K, Fe and P). Field experiments were conducted to assess the effects of saline irrigation with 1.0 M NaCl and extra water added to 0% or 10% Zander on survival and growth, consequently, seedling growth significantly decreased with increase in soil salinity. Survival and growth increased with increase in extra water. The additional irrigation water caused an increase in the uptake of Ca++ and increased the Ca++/Na+ and K+/Na+ ratio. Zander did not appear to reduce net uptake of Na+ and its transport to shoot tissues. Mg++, P, K+ and Ca++ content significantly decreased in plants in response to salinity. Possible mechanisms to avoid Na+ toxicity in A. saligna in response to salinity included increasing the supply of Ca++. Extra Ca++ applied into the medium with and without salt increased survival and growth even in the absence of Zander. Calcium increased uptake of Ca++ and increased Ca++/Na+ and K+/Na+ ratio.

The main purpose of this thesis is to empirically calculate the welfare changes which might be expected to result from potato yield reductions caused by ambient ozone loadings in the Lower Mainland of British Columbia. The objectives of the research are: (1) to review the scientific literature pertaining to the effects of ozone loadings on agricultural crops; (2) to review the methodologies employed in previous regional economic assessments of ozone damages; and (3) to apply an economically defensible technique to the analysis of welfare losses due to ozone. Ozone in the Lower Mainland may be pictured as being restricted laterally by the mountain ranges surrounding Vancouver, and vertically by stagnant high pressure systems. Land/sea breezes aid in transporting ozone and its precursors from Vancouver up the Fraser Valley towards important crop growing regions. The highest levels of ozone occur during spring and summer coinciding with the most active season for many crops. Seasonal ambient ozone dose, measured as hours-ppm>0.10ppm was found to be high in rural areas, especially Abbotsford, during the late 1970's and early 1980's, dropping to low levels in more recent years. Potatoes are one of the economically important crops in the Lower Mainland known to be sensitive to ozone. Potato tuber weight reductions are estimated to have reached 16.5 percent in the Abbotsford region in 1981 at seasonal ambient ozone loadings. An aggregate supply/demand model is set up for potato production in B.C. based upon prior estimates of supply and demand elasticities. This model assumes the price in the B.C. market is set exogeneously by U.S. imports. Thus, all policy relevent welfare changes affect producers' quasi-rent alone. Sensitivity of the model to import price, and the price elasticity of supply is tested. A range of welfare estimates is reported for a variety of ambient ozone loadings. The total damages to potato producers, assuming all regions of B.C. are affected by the same seasonal dose as Abbotsford, are calculated to be around one million dollars at ambient ozone loadings in four out of eight years. A peak occurred in 1981 at 2.4-2.9 million dollars total damages. Damages may be overestimated because 20-30 percent of potato production takes place outside the Lower Mainland, Abbotsford often appears to receive higher ambient ozone loadings than other regions, and not all potato cultivars grown in the Lower Mainland are as sensitive to ozone as that employed here. However, there are also reasons to be cautious over discounting these estimates as too large. Potato response to ozone is restricted to tuber weight reductions while other important effects may include increased plant stress and damage to crop quality. In addition, missing air quality information for some years and stations, suggests that actual ozone dose could be higher than calculated.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

The NDSU EarlyGEM or the Early Germplasm Enhancement of Maize (Zea maize L.) is a long term incorporation program designed to increase the genetic diversity of short season hybrids. Starting in 1999, exotic GEM breeding crosses derived from temperate accessions: BR52051, CH05015; tropical accessions: SCR01, CUBA17, FS8B; and tropical hybrid DKB844 along with late checks: B73, Mo17, and Iowa Stiff Stalk Synthetic (BSSS), were adapted to short-seasons and incorporated via a modified backcross (BC) procedure. This study was designed to assess the genetic diversity in exotic derived BC1:S1 lines and their competitive potential as sources of new and unique hybrids. Useful genetic diversity was evaluated with testers belonging to opposite heterotic groups, LH176 representing a non stiff stalk and TR3026 x TR2040 a stiff stalk testers and were tested in five North Dakota environments over two years (2009 and 2010). All the traits showed highly significant (P<0.01) differences across genotypes except root and stalk lodging. Among 236 experimental testcrosses, 64 were statistically not different (LSD, 0.05) to industry hybrids for grain yield. BC derived lines from BR52051, CHO5015, DKB844 showed diverse alleles for low grain moisture (below 87 relative maturity days) at harvest and high grain yield. SCR01, BR52051, CHO5015 and CUBA117 derived lines produced hybrids with high grain oil (4. 9% vs. 4.1%) and grain protein (10.4% vs. 9.1%) contents compared to top checks. The results showed that the exotic incorporations are the sources of unique new alleles for early maturing maize not present in existing US germplasms (e.g. B73, Mo17, and BSSS). Even though each exotic cross was unique to integrate diverse alleles, utilizing multiple unique exotic crosses for incorporation showed large variation for specific traits. Phenotypic correlations of traits showed grain moisture played the most important role for short season hybrid development. Exotic incorporation through NDSU EarlyGEM has shown a new way of breeding early maturing maize keeping the breeding program open and genetic diversity high.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Corinne Valdivia. Includes bibliographical references.

Over 80% of wild angiosperms are reliant upon animal pollination for fruit and seed set and bees and other insects provide a vital pollination service to around a third of the crops we produce. Habitat loss, climate change and disease spread all threaten pollinator populations, with local declines and range contractions in honeybees and bumblebees leading to concerns that crop production may suffer as a result of pollinator shortages. Whilst agriculture and wildlife are often presented as being at odds with one another, the relationship between farmers growing pollination dependent crops, and the bees and insects that service them could be mutualistic. Flowering crops planted by farmers can provide an important source of forage to wild bees, whilst in return wild bees can contribute to ensuring farmers achieve adequate yields of marketable crops. The potential of this mutualistic relationship can be maximised by farmers by adopting management practices that reduce harm to, and enhance the wellbeing of, the wild bees around their farm. A group of common pesticides (neonicotinoids) used by farmers have recently been linked to pollinator ill health. Sub-lethal effects resulting from exposure to the neonicotinoid imidacloprid have been reported in honeybees and bumblebees, with bumblebee reproductive success found to diminish as a result of exposure to field realistic doses of this agrochemical. Here, the mechanism behind the reduced queen production in bumblebee colonies is suggested, with bees exposed to imidacloprid showing reduced efficiency in foraging for pollen. Farmers dependent upon pollinating insects for crop production can opt to avoid the use of pesticides known to harm these insects, however future studies are needed to identify safer alternatives that can be use in their place. Farmers can choose to increase the number of bees at their farms by utilising domesticated honeybees and purchasing commercially reared bumblebees. The use of these pollinators can ensure a minimum number of bees in the vicinity of a crop, and facilitate the production of crops at times when wild bee numbers are low. Concerns have been raised, however, regarding the use of commercially reared bees, mostly in regard to pathogen and parasite transmission, but also in respect to the possibility of outcompeting native species. Here the frequency and severity of attacks on commercial Bombus terrestris colonies, by the wax moth, an understudied bumblebee pest, are examined. Wax moths were found to infest almost half of the bumblebee nests deployed at fruit farms, with around a third of infestations resulting in nest destruction. Farmers investing in commercial bees will want to reduce the impact of harmful pests that may result in a reduced pollination service being delivered. Wax moth infestation rates at the study farms using commercial bees were high and the potential of a ‘spill- back’ effect on wild bees was examined. No evidence was found to suggest that nests in close proximity to these farms were any more or less likely to suffer from an attack than nests situated further away. Nest size was found to be the most significant predictor of an infestation, with larger nests more prone to wax moth attacks. Whilst farmers can utilise domesticated and commercially reared bees, relying on one source of pollination is inherently risky, and the most robust service will likely be provided by a range of pollinators. As well as reducing the use of chemicals known to harm beneficial insects, farmers can improve the habitat around their farms to help encourage and sustain wild pollinator populations. Sowing flower strips has been found to increase the abundance and diversity of pollinating insects, however, studies linking the use of these strips to crop production are lacking. Here we demonstrate for the first time that sowing small flower strips, adjacent to strawberry crops serviced by both wild and managed bees, can increase the overall number of pollinators foraging on the crop. This thesis contributes to our understanding of the implications of farm management decisions on pollinator health. It provides experimentally based evidence to guide farmers in making informed decisions regarding the future of crop pollination services and highlights the need for an integrated approach to managing pollination services for sustainability.

A jabuticabeira (Plinia sp.) é uma espécie de difícil propagação vegetativa e um protocolo eficiente para tal ainda não foi definido. O objetivo deste trabalho foi investigar a eficiência de técnicas de propagação vegetativa da espécie e desenvolver um protocolo eficiente para desinfestação e estabelecimento inicial de explantes in vitro. Testou-se o potencial de enraizamento de estacas lenhosas de P. cauliflora, utilizando quatro concentrações de ácido indolbutírico (AIB) (0, 2000, 4000 e 6000 mg L-1) e dois procedimentos (corte vertical e anelamento da estaca); e o potencial de enraizamento de estacas apicais herbáceas de P. cauliflora, utilizando cinco concentrações de AIB (0, 2000, 4000, 6000 e 8000 mg L-1) e em duas épocas de implantação (outubro e dezembro). O percentual de enraizamento das estacas foi avaliado após 180 dias da implantação dos experimentos. Foi testada também a compatibilidade de enxertia de três espécies de jabuticabeira (P. cauliflora, P. trunciflora, P. jaboticaba) sobre porta-enxertos de P. cauliflora, em duas épocas de implantação (maio e agosto). Avaliou-se o percentual de enxertos brotados e o número e tamanho de brotos, após 90 dias da implantação. Para alporquia, foram testados dois diâmetros de ramo (1,0-1,5 cm e 2,0-2,5 cm) e duas larguras do anelamento (1,5 cm e 3,0 cm), na espécie P. cauliflora. Avaliou-se o percentual de enraizamento e o número e tamanho de raízes, após 180 dias da implantação do experimento. Testou-se também o período de imersão (5, 10 e 15 minutos) em hipoclorito de sódio a 1,25% no estabelecimento in vitro de explantes caulinares e radiculares de seedlings de P. trunciflora. Avaliou-se o percentual de contaminação e o número de brotos e folhas dos explantes, após 45 dias de incubação. Observouse que o enraizamento de estacas lenhosas é dependente da aplicação de AIB, sendo que o maior percentual de enraizamento (50%) foi obtido na maior concentração de AIB (6000 mg L-1) conjugada com o corte vertical. Para as estacas herbáceas, o enraizamento foi baixo (máximo de 10%). Entretanto, há o potencial de enraizamento e, por isso, ajustes na técnica devem ser testados para maximizá-lo. A enxertia e a alporquia são técnicas recomendáveis para propagação da jabuticabeira, pois proporcionam alto percentual de formação de mudas. Há compatibilidade aparente entre as três espécies enxertadas sobre P. cauliflora. A utilização de garfos retirados de plantas em frutificação deve ser evitada, pois ocorre inibição da brotação posterior dos enxertos. Na alporquia, ramos de diâmetro superior a 2,0 cm, proporcionam enraizamento de 87,5% e maior número e tamanho de raízes, em relação a ramos de menor diâmetro. A utilização do menor tempo de imersão (cinco minutos) em hipoclorito de sódio 1,25% é eficiente para desinfestação dos explantes caulinares de seedlings de jabuticabeira e permite seu estabelecimento inicial in vitro, proporcionando o desenvolvimento de brotações.
The jabuticaba tree is a specie of difficult vegetative propagation and an efficient protocol has not been defined yet. The aim of this work was to test the efficiency of vegetative propagation techniques for jabuticaba tree and develop an efficient protocol for disinfection and initial establishment of in vitro explants. It was tested the rooting potential of wood cutting of P. cauliflora, utilizing four concentrations of Indolbutiric Acid - IBA (0, 2000 , 4000 and 6000 mg L-1) and two procedures (cross section and cuttings girdling); and the rooting potential of softwood terminal cuttings of P. cauliflora, utilizing five concentrations of IBA (0, 2000, 4000, 6000 and 8000 mg L-1) in two periods of implantation (October and December 2007). The rooting potential of cuttings was evaluated after 180 days of the beginning of the experiments. It was also tested the compatibility of grafting of three species of jabuticaba tree (P. cauliflora, P. trunciflora, P. jaboticaba) on rootstocks of P. cauliflora, and two periods (May and August). It was evaluated the survival percentage of grafting, number and size of shoots, after 90 days of the beginning of the experiment. For air layering techniques, it was tested two diameters of branch (1.0-1.5 cm and 2.0-2.5 cm) and two widths of girdling (1.5 cm and 3.0 cm) in P. cauliflora. It was evaluated the rooting percentage, and number and size of roots, 180 days after the beginning of the experiment. It was also tested the period of immersion (5, 10, 15 minutes) in 1,25% sodium hypochlorite solution in the in vitro establishment of shoot and root of the seedlings explants of P. trunciflora. After 45 days of incubation it was evaluated the percentage of contamination and number of shoots and leaves in each explant. It was observed that rooting of wood cutting is dependent of application of IBA, so the biggest rooting percentage (50%) was obtained in biggest concentration of IBA (6000mg L-1) associated with cross section. For the softwood terminal cuttings, the rooting was small (maximum of 10%). Meantime, exist the potential of rooting, and, changes of technique must be tested for maximization. The grafting and the air layering techniques are recommended for jabuticaba tree propagations, because this techniques provide high percentage of plants formation. There is visible compatibility between the three species grafted on rootstocks of P. cauliflora. The utilization of grafts collected from plants in fructification should be avoided, because they reduce the percentage of plants establishment. In air layering techniques, branches with diameter of 2.0 cm provides higher percentage of rooting and the biggest number and size of roots in relation of branches with small diameter (1.0 to 1.5 cm). The utilization of less time in immersion (five minutes) in 1,25% sodium hypochlorite solution is efficient for shoots explants disinfestations of jabuticaba tree seedlings and allows the initial in vitro establishment, providing development of shootings.

Vegetable production in greenhouses is an important and productive economic activity for agricultural businesses in Southern Europe. One of the most risky factors affecting this activity is the use of plant protection products (PPP). Several studies have demonstrated that the use of vertical boom sprayers in greenhouses has several advantages over that of traditional spray guns, such as improved spray distribution, reduced labour costs, and reduced operator exposure. On the other hand, canopy characterization is important for a better adjustment of the amount of pesticide/mixture sprayed, and is a key factor in spray process improvement enabling a significant reduction in the quantity of PPP used, which increases the efficiency of the process. The main objective of this doctoral thesis is to improve the efficiency of the pesticide application process for greenhouse crops by two actions were planned: a) adding an air assistance device to a manually pulled trolley with vertical booms, b) developing a method for canopy characterization. The effect of the addition of the air assistance on a modified hand-held pulled trolley sprayer was evaluated using two different crop fields (tomato with high and low canopy density) and several sprayer types (nozzle type, air assistance, and spray volume). Deposition on the canopy, deposition coverage, and deposition distribution uniformity have been assessed. No significant differences on deposition were obtained with the reference system applying high volume rate compared to modified trolley with air assistance and low volume rate. In general air assistance and flat fan nozzles reduce volume rates while maintaining or improving spray quality distribution. Furthermore, the influence of air-assistance characteristics on spray application was evaluated. For this reason, field tests were arranged for three different sprayers: 1) a modified hand-held trolley sprayer with air assistance high and low velocity; 2) a self-propelled sprayer specifically designed for greenhouse pesticide applications; 3) an autonomous self-propelled sprayer commanded by remote control. Each sprayer was assessed by liquid and air vertical distribution. The evaluation was done considering normalised canopy deposition and liquid losses to the ground. The results indicated that increasing the air velocity does not increase the efficiency of the spray application. In general, the modified hand-held trolley sprayer showed the best results in terms of deposition and uniformity of distribution. These results were confirmed through an evaluation of air uniformity and liquid distribution. The characterization of the canopy was carried out in three different commercial tomato greenhouses, all of which contained crops planted in a twin-row system. Electronic characterization was performed using a LiDAR sensor (LMS-200, SICK) with an 180° angle measurement by scanning a pair of plants from both sides. The main parameters obtained were canopy height, width, and volume, and leaf area. From these parameters, other important parameters were as tree row volume, leaf wall area, leaf area index. A general overview of the results showed an overestimation of the parameters measured manually because of the high definition of the profile obtained with this sensor. An estimation of the canopy volume with the electronic device was shown to be a reliable method for estimating the canopy height, volume, and density. With this sensor was possible to assess the high variability of the canopy density along a row. The determination of the amount of PPP necessary for adequate control of pests and diseases should be adjusted according to the characteristics of the subject canopy. Advancements in spraying techniques that enable fast and robust characterization of major canopy parameters, and advancements in efficient spray distribution technology are essential for improved pesticide spray applications.
La producció de vegetals en hivernacle representa una activitat econòmica i productiva important en l'agricultura del Sud d'Europa. Un dels factors de més risc que afecta aquesta activitat està directament relacionat amb l'ús de productes fitosanitaris. Diversos estudis han demostrat que l'ús de carretons de polvorització amb barres verticals millora la distribució de la polvorització en comparació a les pistoles y llances, reduint els costos de treball i el risc d'exposició de l'operari. D'altra banda, la caracterització del cultiu és un factor clau per a millorar el procés de polvorització millorant l'ajust de la dosificació de producte, permetent una reducció considerable de la quantitat total de pesticida, incrementant l'eficiència del procés general. L'objectiu principal d'aquesta tesi és millorar l'eficiència del procés d'aplicació de pesticides en hivernacles adaptant la polvorització a la vegetació a través de dues accions: a) afegint assistència d'aire a un carretó amb barres verticals arrossegat manualment, i b) desenvolupant un mètode per a la caracterització de la vegetació. La incorporació d'aire en un carretó de polvorització modificat va ser avaluada en dues vegetacions diferents (alta i baixa densitat) i amb varies configuracions diferents (tipus de broquet, assistència d'aire i volum d'aplicació). Es va avaluar la deposició de producte en el cultiu, el recobriment i la uniformitat de la distribució. La deposició obtinguda amb el sistema de referència a volum d'aplicació alt en comparació al carretó amb aire i volum d'aplicació baix no presenta diferències significatives. En general l'assistència d'aire i els broquets de ventall permeten reduir el volum d'aplicació mantenint la qualitat de la distribució de la polvorització. D'altra banda, es va avaluar la influència de la assistència d'aire en la polvorització amb tres màquines diferents: 1) un carretó de polvorització modificat amb assistència d'aire alt i baix; 2) un polvoritzador autopropulsat; 3) un polvoritzador controlat per radio control. Es va caracteritzar cada màquina amb la distribució vertical del líquid i de la velocitat de l'aire. L'avaluació es va fer considerant la deposició de producte en la vegetació i les pèrdues al sòl. Els resultats indiquen que un increment de la velocitat de l'aire no implica una millora de la eficiència de la polvorització. En general, el carretó modificat mostra millors resultats en termes de deposició i uniformitat de la distribució. Aquests resultats han estat confirmats a través de la avaluació de la uniformitat de la distribució de l'aire i el líquid. La caracterització de la vegetació es va realitzar amb tres cultius diferents de tomàquet produït en hivernacle plantats en sistema de parelles. La caracterització electrònica es va realitzar amb un sensor LiDAR (LMS 200, SICK) de 180º d'angle de mesura, escanejant cada parella de plantes per les dues cares de la vegetació. Els paràmetres principals mesurats van ser: alçada, amplada i volum del cultiu i àrea foliar. A partir d'aquestes dades es van poder calcular altres paràmetres importants com el Tree Row Volume, el Leaf Wall Area i l'index d'area foliar. Els resultats mostren una sobre estimació dels paràmetres obtinguts amb els mètodes manuals a causa de l'elevada resolució del perfil a través del sensor. L'alçada de la vegetació, el volum i la densitat es poden estimar de forma fiable a través del volum de vegetació obtingut amb el sensor. Amb aquest sensor es pot avaluar de la variabilitat de la vegetació al llarg de la fila. La determinació de la quantitat de pesticida a aplicar per a un adequat control de plagues i malalties s'ha d'ajustar segons la quantitat de vegetació. El desenvolupament de tècniques que permetin determinar els principals paràmetres del cultiu de manera ràpida i fàcil, així com el desenvolupament de tecnologies que permetin una distribució més eficient del producte, són fonamentals per a una millor aplicació d'aquests productes.
La producción de vegetales en invernadero representa una actividad económica y productiva importante en la agricultura del Sur de Europa. Uno de los factores de más riesgo afectando los parámetros económicos, medioambientales y productivos está directamente relacionado con el uso de productos fitosanitarios. La tecnología más usada para la aplicación de estos productos son las pistolas y lanzas de pulverización. Aun así, diversos estudios han demostrado que, en comparación con las pistolas, el uso de carretillas de pulverización con barras verticales mejora la distribución de la pulverización y reduce los costes de trabajo y el riesgo de exposición del operario. Por otro lado, para mejorar el proceso de pulverización, la caracterización del cultivo es un factor clave en un mejor ajuste de la dosificación del producto, permitiendo una reducción considerable de la cantidad total de pesticida, incrementando la eficiencia del proceso. El principal objetivo de esta tesis es mejorar la eficiencia del proceso de aplicación de pesticidas en invernaderos adaptando la pulverización a la vegetación mediante dos acciones: a) añadiendo asistencia de aire a una carretilla con barras verticales arrastrada manualmente, y b) desarrollando un método para la caracterización de la vegetación. En esta investigación se ha evaluado la adecuación y beneficios de un nuevo prototipo de carretilla con asistencia de aire comparada con la tecnología utilizada habitualmente. En relación a las características de la vegetación, se ha desarrollado una nueva metodología para ser aplicada en tomate de invernadero. La incorporación de aire se probó en una carretilla de pulverización modificada. Ésta fue evaluada en dos vegetaciones diferentes (alta y baja densidad) y con varias configuraciones distintas (tipo de boquilla, asistencia de aire y volumen de aplicación). Para este estudio se evaluó la deposición de producto en el cultivo, el recubrimiento y la uniformidad de la distribución. La deposición en las hojas y la penetración en el cultivo utilizando las boquillas de abanico y asistencia de aire es significativamente más alta en los volúmenes de aplicación alto y bajo. La deposición obtenida con el sistema de referencia a volumen de aplicación alto en comparación a la carretilla con aire y volumen de aplicación bajo no presenta diferencias significativas. En general la asistencia de aire y las boquillas de abanico permiten reducir el volumen de aplicación manteniendo la calidad de la distribución de la pulverización. Por otro lado, también en cultivo de tomate en invernadero, se evaluó la influencia de la asistencia de aire en la pulverización con tres máquinas diferentes: 1) una carretilla arrastrada manualmente con asistencia de aire alta y asistencia de aire baja; 2) un pulverizador autopropulsado; 3) un pulverizador controlado por radio control. Todos los pulverizadores se evaluaron considerando la deposición de producto en la vegetación y su uniformidad, y las pérdidas en el suelo. Además se evaluó la distribución vertical del líquido y de la velocidad del aire y se comparó con los perfiles de vegetación y de distribución de deposición. Los resultados indican que un incremento de la velocidad del aire no implica una mejora de la eficiencia de la pulverización. En general, la carretilla modificada muestra los mejores resultados en términos de deposición y uniformidad de la distribución, especialmente con asistencia de aire baja. Estos resultados han sido confirmados mediante la evaluación de la uniformidad de la distribución del aire y del líquido. Las características del cultivo se han determinado con un sensor terrestre LiDAR 2D. Los experimentos se realizaron en tres cultivos distintos de tomate en invernadero plantados en sistema pareado. La caracterización electrónica se realizó con un sensor LiDAR (LMS‐200, SICK) de 180º de ángulo de medida, escaneando cada pareja de plantas por las dos caras. Los parámetros principales medidos fueron: altura, anchura y volumen del cultivo y el área foliar. A partir de estos datos se pudieron calcular otros parámetros importantes como el Tree Row Volume (TRV), el Leaf Wall Area (LWA), el Indice de Area Foliar (LAI) y el índice de densidad foliar (LAD). En general los resultados muestran una sobreestimación de los parámetros obtenidos con los métodos manuales debido a la alta resolución del perfil medido por el sensor. La altura de la vegetación, el volumen y la densidad se pueden estimar de forma fiable a través del volumen de la vegetación obtenido con el sensor. Además este sensor permite la evaluación de la variabilidad del dosel a lo largo de la fila, siendo importante para la generación de mapas de vegetación.

A identificação de metodologias eficientes para essa escolha de genitores em programas de melhoramento tem recebido grande atenção dos pesquisadores. O cruzamento dialélico é muito utilizado com esta finalidade; entretanto, à medida que o número de genótipos a serem testados aumenta, sua utilidade torna-se progressivamente inviável. Alternativas como medidas de dissimilaridade (baseadas em dados morfológicos, moleculares e genealógicos) têm sido propostas. Deste modo, o objetivo deste trabalho foi o de estimar a capacidade geral (CGC) e especifica (CEC) de combinação, heterose e depressão endogâmica, nas gerações F1 e F2, através de cruzamento dialélico de dez genótipos de trigo, bem como avaliar o relacionamento entre genitores e o desempenho de seus híbridos, com as medidas de dissimilaridade anteriormente citadas. Dez genitores elite foram cruzados de forma dialélica, desconsiderando os recíprocos. Os resultados obtidos revelaram uma maior participação dos efeitos aditivos na expressão genotípica das constituições utilizadas. Os parentais FUNDACEP 50, Pampeano, BRS 208 e Abalone foram os que apresentaram os maiores valores de CGC para rendimento de grãos, evidenciando o potencial destes genótipos para utilização em cruzamentos a fim de obter progênies superiores. Também, as combinações envolvendo os genótipos BRS Guamirim x BRS 208, UTF 0506 x BRS Timbaúva, BRS 208 x Abalone, CD 115 x Abalone e BRS Timbaúva x Abalone, apresentaram elevado grau de heterose e baixa perda de vigor para os caracteres de maior importância agronômica. A heterose revelada pelo F1 não garante populações segregantes promissoras, pois em muitos casos não ocorreu associação da heterose do F1 com desempenho dos bulks das gerações F2. As estimativas das correlações entre as matrizes de dissimilaridade permitiram observar a concordância existente entre as matrizes de dissimilaridade Morfológica+AFLP x Molecular AFLP (0,466) e entre Morfológica+AFLP x genealógica (0,42). A distancia genealógica foi positivamente associada com os caracteres massa de 100 grãos e peso de grãos por planta nas gerações F1 (0,67 e 0,62, respectivamente) e F2 (0,62 e 0,59, respectivamente), o que lhe confere moderada confiabilidade em substituir os cruzamentos dialélicos na escolha dos genitores. Em contrapartida, as medidas de distancia morfológica e combinada (molecular AFLP+morfológica), não foram associadas com o desempenho dos híbridos, em ambas as gerações avaliadas.
The identification of efficient methodologies for the choice of parents in breeding programs has received great attention from researchers. The diallel cross is widely used with this purpose, however, as the number of genotypes to be tested increases, its utility becomes increasingly unviable. Alternatives such as measures of dissimilarity (based on morphological dates, molecular and genealogical) have been proposed. Thus, the objective of this study was to estimate the general (CGC) and specific (CEC) of combining , heterosis and inbreeding depression in F1 and F2 generations, through diallel of ten wheat genotypes and to assess the relationship between parents and the performance of their hybrids, with the dissimilarity measures described above.Ten elite parents were crossed in a diallel form, disregarding the reciprocal. The results revealed a greater participation of additive effects on phenotypic expression of the constitutions used. The parents FUNDACEP 50, Pampeano, Abalone and BRS 208 presented the highest values of CGC for grain yield, demonstrating the potential of these genotypes for use in crosses to promote superior progenies.Also, the combinations involving the genotypes BRS Guamirim x BRS 208, UTF 0506 x Timbaúva BRS, BRS 208 x Abalone, CD 115 x Abalone and BRS Timbaúva x Abalone, showed a high degree of heterosis and low inbreeding for characters of greatest agronomy importance. Heterosis revealed by F1 does not warrant segregating populations, because in many cases there was no association with heterosis of F1 and with performance of bulks on F2 generations. Estimates of correlations between the dissimilarity matrices allowed to observe the correlation between the dissimilarity matrices Morophological + AFLP x Molecular AFLP (0.466) and between Morophological + AFLP x pedrigree (0.427). The genealogical distance was positively associated with weight of 100 grains and grain weight per plant in F1 generation (0.67 and 0.62, respectively) and F2 (0.62 and 0.59, respectively), it gives moderate reliability to replace the diallel in the choice of parents. In contrast, the measures of morphological distance and combined (morphological + molecular AFLP), were not associated with the performance of hybrids, in both generations avaliable.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第15421号
農博第1806号
新制||農||979(附属図書館)
学位論文||H22||N4520(農学部図書室)
27899
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 間藤 徹
学位規則第4条第1項該当

A system dynamics model is developed to study the technology adoption process (TAP) of modern agriculture input technology such as the biotechnologies. The work shows that the system dynamics approach is appropriate to integrate the different components considered in the TAP conceptual framework elaborated in this work. The conceptual framework illustrates the different system components found important in the literature, portfolio decision-making, learning, information gathering, uncertainties and economics perceptions and their involved relationships.
The model is first calibrated and validated using the case of soybeans adoption versus corn uses in Quebec from 1987 to 1998. Validation is performed through five tests, namely visual, statistical and sensitivity, modularity and extendibility are performed to show the relevancy of the approach.
The model is then applied to the case of four input biotechnology crops. Again three types of validation tests are carried out. Results show that the model predicted the shape of the curve for all application fields.

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The deterioration of harvested sugarcane as a result of bacterial growth causes major losses of sucrose and a build-up of exopolysaccharides (EPS). Polysaccharides present during production increase the massecuite viscosity, which negatively influences evaporation and crystallisation. In this study 38 culturable EPSproducing bacteria were isolated from milled sugarcane. Analysis of the EPS showed the ubiquitous presence of glucose, however, 14 polysaccharides also contained mannose, fructose or galactose. In vitro treatment using Chaetomium erraticum dextranase to evaluate is effectiveness indicated that 37 of the EPS were hydrolysed to some extent. There were 21 polysaccharides that were only partially digested. The capacity of the isolates to produce EPS on different sugars indicated a correlation between sucrose and polysaccharide formation in 37 isolates. The results indicate there are more species involved in EPS production than previously thought as well as the presence of non-dextran polysaccharides.
AFRIKAANSE OPSOMMING: Bakteriële groei veroorsaak ‘n afname in gehalte, sukrose en ‘n verhoging in die hoeveelheid van eksternepolisakkeriede (EPS). Die verhoogde konsentrasie van polysakkariede gedurende die verwerkingsprosses veroorsaak ‘n verhoging in “massecuite” viskositeit. Hierdie verskynsel het ‘n nadelige uitwerking op die verdamping en kristalvorming van die produk. In gemaalde skuikerriet was 38 groeibare EPS-produserende bakterieë geisoleer. Die geanaliseerde EPS van hierdie bogenoemde bakterieë was daar in almal glukose teenwoordig. In 14 van hulle was mannose, fruktose en galaktose ook gevind. Die in vitro effektiwieteit van Chaetomium erraticum dekstranase op die EPS het gewys dat 37 het tot ‘n mate gehidroliseer maar 21 was net gedeeltelik verteer. As gevolg van die bo-genoemde resultate was daar gevind dat sukrose was ‘n noodsaaklike subtraat vir EPS produksie in die geisoleerde bakterieë. In hierdie studie was bevestig ‘n groter verskiedenheid EPS-produserende bakterieë gevind was en dat hulle assosiasie aan sukierriet prossering meer kompleks is as wat vooreen gedink was.

Die Ernährungssicherheit ist bedroht, unter anderem durch den Klimawandel. Eine Zunahme der Wetterextreme kann zu deutlichen Ertragseinbußen führen. Deshalb ist eine Quantifizierung des Klimaeinflußes auf die Landwirtschaft nötig um eine rechtzeitige Anpassung zu ermöglichen. Die vorliegende Dissertation schlägt daher Verbesserungen für Ertragsmodelle in Bezug auf Klimaextreme vor. Der erste Teil ist eine Metastudie zur Strukturierung von Wissen. Eine neue Methode wird zum Aufbau eines enzyklopädischen Netzwerks verwendet. Dieses erlaubt Vorschläge zur Modellverbesserung abzuleiten. Zwei davon, Ozonschäden und extreme Temperaturen, werden folgend behandelt. Der zweite Teil behandelt Ertragseinbußen durch Ozon. Das Ertragsmodell LPJmL wird um Ozonstress erweitert und damit globale Ertragseinbußen bei Weizen und Soja abgeschätzt. Wasserdargebot, Temperatur und CO2-Konzentration werden berücksichtigt, im Gegensatz zu früheren Abschätzungen. Laut Analyse kann Ozon zu Ernteeinbußen von bis zu 50% führen. Der dritte Teil behandelt Schäden durch hohe Temperaturen. Es wird untersucht, inwieweit neun Modelle die Effekte von Hitze auf Mais, Soja und Weizen in den USA abbilden. Das Modellkollektiv kann beobachtete Verluste quantitativ reproduzieren und legt Wasserstress als Ursache dafür nahe. Erhöhte CO2-Konzentrationen können laut Modellen die Ernteeinbußen nicht verringern, im Gegensatz zu gegenwärtigen Überzeugungen. Der vierte Teil enthält ein statistisches Modell, mit dem der Anteil des Wetters an globalen Ertragsschwankungen berechnet wird – unter Berücksichtigung von Hitze- und Froststress. Dieser Anteil wird bei Mais, Soja und Weizen global auf 15-42% beziffert. Weitere Ergebnisse zeigen über 50% Vorhersagekraft des Modells bereits zwei Monate vor der Ernte. Die vorliegende Arbeit stellt die negativen Einflüsse von Ozon und Hitze für die Landwirtschaft und damit die Ernährungssicherheit heraus. Die Vorteile der Anwendung mehrerer Modelltypen werden hervorgehoben.
Agricultural production and thus food security are under pressure, in particular by climate change. Climate extremes are likely to increase and may diminish harvests. Hence it is decisive to quantify such impacts. Consequently, this thesis aims at improving crop models with respect to climate extremes. The first part is a meta-study for structuring knowledge on crop physiology. A novel method is used to build a network-based encyclopedia. This allows for deducing improvement suggestions for crop models. Two of these suggestions (ozone and extreme temperatures) are treated in the following. The second part analyses crop losses from ozone damage. The crop model LPJmL is enhanced by ozone stress and used to simulate global historical wheat and soybean yield losses. Crop water status, temperature and CO2 are considered as modulators of ozone damage – an improvement over previous global assessments. The analysis indicates that ozone can cause yield losses up to occasional 50%. The third part treats effects of high temperatures on yields. It is assessed to what extent nine crop models can reproduce effects of heat on maize, soybean and wheat yields in the US. The model ensemble simulates observed yield losses in the correct quantities and suggests that they stem from water stress. It is hypothesized that future US yields could suffer from heat losses even under elevated CO2, contrary to current convictions. The fourth part describes a statistical model to assess the global share of weather-driven yield variability, considering heat and frost stress. The influence of weather on yield variability of maize, wheat and soybeans is quantified as 15-42% globally. Results also suggest a yield forecasting capacity of more than 50% two months before harvest in several countries. This thesis underlines the negative influence of ozone and high temperature stress on agricultural production and, consequently, food security. The benefits of using diverse types of models are highlighted.

Maize (Zea mays L.) ranks third as a food crop after wheat and rice and is characterized not only as a cereal crop but also as a vegetable. Maize used as a vegetable is known as “baby corn”. Baby corn consists of unfertilized young ears harvested 2 or 3 days after silk emergence. The present study was implemented in 2009 at Western Kentucky University Agriculture Research and Education Center (36.93 N, 86.47 E) in Bowling Green, Kentucky. The purpose of the study was to compare the effect of different schemes of harvest on baby corn (BC) yield, grain maize (GM) yield, and estimated economic return. Experimental harvest treatments were 1) no BC harvest, only GM harvest, 2) first harvest as BC, final harvest as GM, 3) first and second harvests as BC, final harvest as GM, and 4) first, second, and third harvests as BC, final harvest as GM. Average estimated BC yields (Kg/ha) for Treatments 2, 3, and 4 were 1445.1, 2681.8, and 3437.5; GM yields (Kg/ha) for Treatments 1, 2, and 3 were 12522.2, 8226.5, and 1380.9; respectively. Since few grain kernels were found after three harvests for BC (Treatment 4), no usable GM yield was produced. BC and GM yields were used for evaluating the economic returns. Results indicated that the sequence of best economic returns would be obtained by harvesting BC three times (Treatment 4), first two harvests for BC and the final for GM (Treatment 3), first harvest for BC and subsequent for GM (Treatment 2), and only for GM harvest (Treatment 1). Although the pattern for only BC harvest was the most profitable system, the human labor requirement and critical timing of harvest limited its production. In states similar to Kentucky, BC could only be grown as an additional crop or to supplant a limited amount of traditional GM hectarage.

Pigeonpea (Cajanus cajan) is a sub-tropical and tropical pulse rich in plant-based protein, carbohydrates, minerals, and vitamins. Helicoverpa armigera is the most devastating insect pest in pigeonpea. This study focussed on deciphering the molecular host plant resistance (HPR) mechanisms applied by Cajanus scarabaeoides a wild pigeonpea against insect using transcriptomic and proteomic studies. These HPR mechanisms were transferred to the cultivated pigeonpea via interspecific hybridisation, and they are stable at F2 generation. The study outcome provides a unique insight into the insect resistance mechanisms employed by C. scarabaeoides and lays the foundation for further studies and applications.

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Plant diseases are among the major causes of food insecurity. In South Africa the wheat fungal diseases including stem rust caused by Puccinia graminis f. sp. tritici, leaf rust caused by P. triticina and stripe rust caused by P. striiformis f. sp. tritici are the most important. Genetic resistance is a viable way of protecting wheat crops against the wheat rusts, especially cultivars carrying multiple genes that confer durable resistance. In order to breed for multi-gene resistance an effective breeding strategy that allows for selecting multiple resistance genes and other desirable traits needs to be devised. The aim of this study was to identify a number of genotypes with combinations of different rust resistance genes, good grain yield and end-use quality out of an existing pre-breeding population and thereby identify superior parents. In order to achieve the stated aim the following objectives have been identified: identify wheat lines through marker-assisted selection (MAS) carrying the gene complexes, Sr31/Lr26/Yr9, Lr24/Sr24, Lr37/Sr38/Yr17, Lr34/Yr18 and Sr2; to develop inbred lines to evaluate selected lines under field trials. From the initial subset of 64 lines, 60 were chosen and advanced to the doubled haploid (DH) phase and seed multiplication. The 60 lines either carried one or more of the three rust resistance gene complexes. The genes that were the most prominent were Sr31/Lr26/Yr9 and Lr24/Sr24. The selected lines were incorporated into a DH seed multiplication phase. After 4 cycles of seed increases and preliminary field evaluation during multiplication, 15 lines were chosen and subjected to multi-location field trails. The extensive multi-location field trails carried out in this study aided in identifying genotypes from the 15 MS-MARS lines with good adaptability and stability in regards to yield and baking quality. An important observation was that the molecular markers employed to indentify quality loci correlated well with the genes encoding the HMW-GS 5, 10 and 12 as observed with the Agilent© 2100 Bioanalyzer. In future studies the lines which performed the best could be re-introduced into the existing MSMARS pre-breeding programme of the Stellenbosch University’s Plant Breeding Laboratory (SUPBL). The frequencies of desired alleles could be increased in this manner. Since the majority of these characteristics are influenced by quantitatively inherited alleles, using these lines as recurrent parents will increase the frequencies of these alleles in the existing SU-PBL pre-breeding population.
AFRIKAANSE OPSOMMING: Plantsiektes is van die belangrikste oorsake van voedselonsekerheid ter wêreld. In Suid-Afrika is die roesswamme van die belangrikste plantsiektes wat koring produksie beïnvloed. Hierdie siektes sluit in, stamroes wat veroorsaak word deur Puccinia graminis f. sp. tritici, blaarroes wat veroorsaak word deur P. triticina en streeproes wat veroorsaak word deur P. striiformis f. sp. tritici. Genetiese weerstand is ‘n uitstekende manier om koring te beskerm teen hierdie swamsiektes. Weerstand wat gebasseer is op veelvuldige weerstandsgene is veral ‘n goeie middel om genetieseweerstand op ‘n volhoubare basis in koringteling toe te pas. Om veelvuldige weerstandsgene in koringkultivars in te teel word ‘n effektiewe telingstrategie benodig. Die doel van die studie was om genotipes te identifiseer met kombinasies van veelvuldige weerstandsgene vir roes, sowel as goeie eienskappe belangrik vir graanopbrengs en bakkwaliteit. Lyne is geïdentifiseer uit ‘n bestaande voortelingspopulasie van Stellenbosch Universiteit se Planteteelt Laboratorium (SU-PTL) wat geteel was met spesifiek weerstand en opbrengs potensiaal in gedagte. Om die doel van die studie te bereik is sekere doelwitte daar gestel. Hierdie doelwitte sluit in om lyne uit die populasie te selekteer deur middel van merker bemiddelde seleksie (MBS) vir gene naamlik Sr31/Lr26/Yr9, Lr24/Sr24, Lr37/Sr38/Yr17, Lr34/Yr18 en Sr2; om die geselekteerde lyne suiwertelend te maak; sowel as om die suiwertelende lyne in veld proewe in te sluit. Van die oorspronklike stel van 64 lyne, is 60 gekies vir verdere studie. Deur middel van die verdubbelde haploïed (VH) tegniek is die lyne suiwertelend gemaak. Die 60 lyne het een of meer van die geselekteerde gene bevat. Die mees prominente gene was die twee geen komplekse Sr31/Lr26/Yr9 en Lr24/Sr24. Na vier siklusse van saadvermeerdering en voorloppige seleksies is 15 lyne ingesluit by ‘n multi-omgewing veldproef. Hierdie uitgebreide multi-omgewing veldproewe het gehelp om individue uit die 15 lyne te identifiseer wat oor goeie aanpasbaarheid en stabiliteit beskik met betrekking tot opbrengs en bak kwaliteit. Die molekulêre merkers gebruik om die gene verantwoordelik vir die kodering van HMGGS 5, 10 en 12 op te spoor het goed gekorreleer met die HMG-GS bande bepaal met behulp van die Agilent© 2100 Bioanalyzer. Toekomstige studies kan moontlik insluit die gebruik van die lyne wat geïdentifiseer was met goeie kenmerke in die bestaande MS-MARS teelprogram van die SU-PTL. Die frekwensies van die verlangde allele kan op hierdie manier in die populasie verhoog word.