Dissertations / Theses on the topic 'Vegetation cultivation'

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19325号
農博第2146号
新制||農||1036(附属図書館)
学位論文||H28||N4953(農学部図書室)
32327
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 縄田 栄治, 教授 舟川 晋也, 教授 神﨑 護
学位規則第4条第1項該当

Thesis (MScFor )--Stellenbosch University, 2003.
ENGLISH ABSTRACT: Species-rich Renosterveld vegetation does not return to old agricultural fields even after many years (10-20) of abandonment. In most cases the fields are slowly taken over by non-indigenous species, particularly alien pasture grasses and African lawn grass. While poor survival of indigenous seedlings due to competition, grazing or any other establishment constraints, might explain the failure of natural vegetation to colonise old fields, here I am testing the hypothesis that recolonisation by indigenous plant species is limited by seed dispersal. I have quantified changes in seed density with distance from the natural vegetation into old fields using seed traps and soil seed bank assessment. I have also looked at seed dispersal in the dung of large herbivores. Shrubs (with the exception of Eytropappus rhinocerotis) were poorly represented in the seed rain indicating that they might be seed limited. Dicerothamnus rinocerotis (a dominant shrub in Renosterveld) and certain geophytes (that were recovered in the soil bank) have proven that seed dispersal is not the primary constraint to their return to ploughed fields. Dicerothamnus rinocerotis produces a large number of seeds that are dispersed long distances into the old field and a number of geophytes were well represented in the soil bank. Large herbivores are dispersing a lot of herbaceous forbs in their dung but make very little contribution to the dispersal of indigenous tussock grass and shrubs. Seeds of indigenous Renosterveld tussock grasses (e.g Tribolium hispidum) were restricted to the edge of the natural vegetation. My research has shown that some indigenous seeds, particularly those dispersed in wind and through large mammals, do reach the old ploughed field. I therefore conclude that seed dispersal is not the primary constraint to the natural recovery of populations of some indigenous plant species on old fields, but may limit recovery of certain indigenous geophytes, grasses and shrubs.
AFRIKAANSE OPSOMMING: Spesie-ryke Renosterveld plantegroei hervestig nie op ou landerye nie, selfs ná baie jare (l0-20) van verlating. Oor die algemeen word hierdie grond stadig oorgeneem deur uitheemse spesies, veral uitheemse weidingsgrasse en kweekgras. Terwyl swak oorlewing van inheemse saailinge as gevolg van kompetisie, weiding of enige ander vestigingsbeperkinge, die mislukte vestiging van natuurlike plantegroei op ou benutte grond kan verduidelik, toets ek hier die hipotese dat hervestiging deur inheemse plantspesies deur saadverspreiding beperk word. Ek het veranderinge in saaddigtheid oor afstand vanaf die natuurlike plantegroei na ou landerye gekwantifiseer, deur gebruik te maak van saadopvangsvalle en sand saadbank beraminge. Ek het ook gekyk na saadverspreiding in die mis van groot herbivore. Struike (behalwe Eytropappus rhinocerotis) was swak verteenwoordig in die "saadreën", wat mag toon dat struike saadbeperk is. Eytropappus rhinocerotis ('n dominante struik in Renosterveld) en sekere geofiete (wat in die saadbank gevind is) het bewys dat saadverspreiding nie die hoofbeperking is vir hulle terugkeer na geploegde lande nie. Eytropappus rhinocerotis produseer 'n groot hoeveelheid saad wat oor groot afstande oor die ou landerye versprei word en 'n aantal geofiete was goed verteenwoordig in die saadbank. Groot herbivore versprei 'n groot hoeveelheid kruidagtige forbe in hulle mis, maar maak 'n baie klein bydrae tot die verspreiding van inheemse polgras en struike. Saad van inheemse Renosterveld polgrasse (bv. Tribolium hispidum) was beperk tot die some van die natuurlike plantegroei. My navorsing het getoon dat sommige inheemse saad, veral dié wat deur die wind en deur groot herbivore versprei word, wel die ou geploegde landerye bereik. Ek maak dus die gevolgtrekking dat saadverspreiding nie die hoofbeperking is vir die natuurlike herstel van populasies van sommige inheemse plantspesies op ou landerye nie, maar mag die herstel van sekere inheemse geofiete, grasse en struike beperk.

碩士
亞洲大學
經營管理學系碩士在職專班
97
Due to the increasing wages, low profit for agricultural production, and lack of farmers in Taiwan for a long time, a lot of farm fields still remain barren. The need for effective utilization of agricultural fallow is appealing by agriculturists, foresters, conservationalists and ecologists recently. Biomass currently accounts for about 15 per cent of the global primary energy consumption and is particularly important as an energy resource in developing countries. It will undoubtedly play an increasing role in the world's energy consumption. Although castor (Rucina communis) – a wild plant species easily grow in dried infertile field, can it makes up this large percentage of our energy resources? Can we grow it in the barren farm to boost the levels of oil/lubricant production instead of imported oil? What impact does their cultivation have on the environment and plantation development? This paper starts with aspects of castor cultivation, harvesting, as well as conversion technologies for biofuels as references cited. This is followed by a look at the environmental impact and economic and social dimensions, including prospects for renewable energy. We then go on to discuss the main potential energy crop- castor. For this species, we give a brief description, outlines the ecological requirements, methods of cultivation, processing and utilization, then finishes with selected references. All those whose work involves biomass production, whether as agriculturalist, student, farmer, producer, planner or policy maker will find this paper an invaluable reference work on the plantation of fast-growing castor – an inedible crop instead of other edible energy resources i.e., rice, corn, wheat , and potato in agricultural fallow. In general, castor is an ideal plant species for the manufacturing of vegetable oil to replace petroleum. Castor will be planting in agricultural fallow of Taichung county, Taiwan as a promising species in oil industry based on renewable biomass resources.

In order to determine if weed control as practised during the establishment phase of tree growth had a beneficial and long term (over a six to eight year rotation) impact on tree performance, a Eucalyptus hybrid clone (GC304) was planted in a field trial in 1990. The trial was situated in the coastal Zululand region near the KwaZulu-Natal town of Mtunzini. Nine different vegetation management treatments were imposed from establishment. These included a weedy control, a manually weeded treatment, a chemically weeded treatment, a 1.2 m row and 1.2 m inter-row weeding, a 0.5 m radius ring weeding, a complete weeding except for a 0.5 m radius ring around the tree, and the use of two legume cover-crops, Mucuna puriens (cowpea) and Vigna sinensis (velvet bean). Initial improvements in tree performance from these competition control treatments were detected from 60 days after planting, and were maintained over seven growing seasons. This occurred despite the absence of competitive vegetation after the first growing season due to reduced light, following crown canopy closure. There were strong indications that initial competition was mainly for moisture and possibly also for nutrients, rather than competition for light. Initially those trees that had weeds within their immediate vicinity were most affected (weedy control, inter-row weeding and the complete weeding except for a 0.5 m radius around the tree). With time, tree performance was more closely related to an increase in the percentage of the area kept free of weeds. The best performing treatment at felling, the manually weeded control, produced 17.1 % and 38.5 % more merchantable timber than the 1.2 m row weeding and the weedy control, at an increased profit of 8 % and 27 %, respectively. Two forms of competition (interspecific and intraspecific competition) were evident in the weedy control at different stages of tree development in contrast to the one (intraspecific competition) in the manually weeded treatment. Interspecific competition resulted in greater variability between the trees in the weedy control by the time canopy closure had occurred. This differentiation in tree size was further enhanced by asymmetric intraspecific competition once the trees had become established. The onset of intraspecific competition was first detected 995 days after planting for the manually weeded treatment and 1641 days after planting for the weedy control. Of the various competition indices that were tested in order to try and explain this differential growth in terms of individual tree performance, none was able to do so to complete satisfaction. The growth rates of different tree size classes were therefore compared for the weedy control and manually weeded treatment. The diverging slopes of the different stem area classes indicated that the larger trees were growing at the expense of the smaller trees. This type of competition is known as asymmetric intraspecific competition. In addition, a comparison was made between the slopes for the weedy and weedfree treatments for similar stem area classes. No significant difference was detected, indicating that similar size classes in these two treatments grew at similar rates. Trees from three treatments were selected (manually weeded treatment, 1.2 m row weeding treatment and the weedy control) and tested for the wood and pulping properties of density, active alkali consumption, extractable content, screened pulp yield, pulp yield per hectare and fibre length and coarseness. The use of Canonical Variate Analysis to determine if there were differences between the three treatments for the variates measured, indicated that they were significantly different. There was a significantly positive trend of an increase in density, extractable content and active alkali consumption with increased weed control. A possible explanation for this could be that the larger trees of the manually weeded treatment were under more stress (from increased intraspecific competition) during the latter phase of their growth. This was demonstrated by comparing the growth rates for these three treatments. The smaller trees of the 1.2 m row weeding treatment and the weedy control exhibited a lower rate of decline. As no significant difference was detected for screened pulp yield between the treatments, any differences in the pulp yield per hectare values could be attributed to differences in the merchantable volume. There was a 22.6 % and 40.8 % increase in the pulp yield per hectare for the manually weeded treatment in comparison to the 1.2 m row weeding treatment and the weedy control. The planting of cover-crops, although beneficial in terms of weed suppression, caused significant tree suppression. This occurred despite the fact that their initial biomass accumulation was slower than that of the natural weed population. Of the two cover-crops, the use of the velvet bean was not considered suitable due to its vigorous vining habit which affected the growth form of the trees. Subsequent work suggests that if the beneficial qualities of cowpeas are to be realised (that of weed suppression, erosion control and nitrogen fixation), a delay in their planting by three months after establishment of the trees should alleviate any negative impacts on tree growth.
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

Plant breeders can select cultivars with physiological traits that confer a growth or yield advantage to individual plants. The extent to which single plant characters influence canopy performance depends on interactions between vegetation and the atmosphere and the non-linear response of physiological processes to the environment. Better understanding of the scaling of photosynthesis and water use will allow the assessment of changes to leaf scale physiological traits at the canopy scale and prediction of the response of vegetation to climate change. This thesis examines the relationship between reduced stomatal conductance and canopy scale water-use efficiency (ratio of instantaneous net canopy photosynthesis to total canopy evaporation). A multi-disciplinary research project was established with two large paddocks of wheat with cultivars of contrasting leaf-scale water-use efficiency, due to inherent differences in stomatal conductance. Intensive measurements were made of C02 and H20 fluxes at leaf and canopy scales. Different stomatal conductances at the leaf scale were reflected at the. canopy scale, although their effects on transpiration were reduced due to canopy boundary layers and soil evaporation. Comparison of scaling from leaf to canopy in the two crops was complicated by their different leaf area indices. To facilitate scaling from leaves to canopies, models of stomatal conductance, leaf photosynthesis and radiation penetration in canopies were used. A comparison of several models of conductance with field data found that using the correlation of conductance with photosynthesis was the best approach. The same model was found to work equally well at the canopy scale, using parameters derived from leaf scale data. Canopy photosynthesis was modelled with a biochemical model of leaf photosynthesis incorporated into different integration schemes. A canopy model which divided the canopy into a single layer of sunlit and shaded leaves was found to be as accurate as a multi-layer model, but simpler and allowed incorporation of within-canopy profiles of photosynthetic capacity. A big-leaf model of canopy photosynthesis was found acceptable if tuned, but the uncertainties increased when it was used to predict responses of canopies with different properties. Photosynthetic capacity, the main parameter of the canopy photosynthesis model, was found to decrease during the day under conditions of mild water stress at both the leaf and canopy scale. Combined models of photosynthesis, conductance and energy balance accurately described diurnal variation of canopy gas exchange. The model predicted that a 40% reduction in stomatal conductance would result in 36% greater leaf transpiration efficiency and 19% greater canopy transpiration efficiency (ratio of gross canopy photosynthesis to canopy transpiration) which compared favourably with field measurements, but depended on the magnitude of the conductance and wind speed. Measurements of air temperature, humidity and surface temperature along a transect across the interface between the two crops with different evaporation rates, showed that advection did occur, but that it had minimal impact on canopy fluxes. It was concluded that reduced stomatal conductance does result in reduced transpiration and better transpiration efficiency at the canopy scale, but that canopy boundary layers and greater soil evaporation reduce the benefit. In this case reduced conductance was also accompanied by greater yield, although this result depends on the availability of soil water. The models presented were an effective tool for scaling nonlinear physiological processes from leaves to canopies and provide a useful framework for assessing the impact of climate change on vegetation.

碩士
國立嘉義大學
農學研究所
94
This study aims to explore effect of Peters 20N-20P2O5-20K2O fertilizer concentration on four typical floral type (color): Vegetative growth of the 4.5 cm and 7.5 cm pot seedling. The result shows under 0.5 g/L and 1.0 g/L fertilizer concentration treatment, Large White (Phal. I-Hsin Cream ‘KHM695’), Large Red (Dtps. I-Hsin New Girl ‘KHM710’), Waxy Yellow (Phal. I-Hsin Sunflower ‘KHM95-1’) and Mini Red (Dtps. I-Hsin Helen ‘KHM69’) planted in spring have better shoot growth amount. From 4.5 cm to 7.5 cm pot seedling of four Phalaenopsis hybrids planted in spring, the result also shows that the shoot growth is better under 1.0 g/L treatment. In root growth of Large White (Phal. I-Hsin Cream ‘KHM695’) and Mini Red (Dtps. I-Hsin Helen ‘KHM69’), the root fresh and dry weight increases following higher fertilizer concentration. Although the 4.5 cm pot seeding of five Phalaenopsis hybrids planted in fall could have more leaf numbers under 2.0 g/L fertilizer concentration treatment, to evaluate the leaf span, leaf length, leaf width and shoot growth fresh and dry weight, those seedlings grow better under 0.5 g/L and 1.0 g/L fertilizer concentration treatment. The reason is seedlings have growth inhibition of shoot and root growth when the fertilizer concentration rises to 2.0 g/L. In four Phalaenopsis hybrids planted in spring, the leaf number, leaf span, leaf length and shoot fresh and dry weight grew best under 1.0 g/L fertilizer concentration treatment, but to consider the root growth, the root number had no obvious difference under various fertilizer concentration; the root length and the root fresh and dry weight were the highest when using no fertilizer, and the relationship between the root length, root fresh and dry weight and fertilizer concentration showed an inverse ratio. Then, from 7.5 cm to 10.5 cm pot seedlings planted in spring, the leaf span and leaf length of Mini Red (Dtps. I-Hsin Helen ‘KHM69’) grew best under 0.5 g/L fertilizer concentration treatment, but the leaf number, leaf span, leaf length and leaf width of the other three hybrids grew best under 1.0 g/L fertilizer concentration treatment. The leaf number, leaf span, leaf length, and shoot fresh and dry weight of the 7.5 cm pot seedling planted in fall grew best under 1.0 g/L and 2.0 g/L fertilizer concentration treatment, but the root fresh and dry weight grew best under 2.0 g/L fertilizer concentration treatment; the root number, root length and root fresh and dry weight of fall grew best when using no fertilizer, and decreased by degree following higher fertilizer concentration. The SPAD value of the 4.5 cm pot seedling of four Phalaenopsis hybrids planted in spring and fall was the lowest when using no fertilizer. From 4.5 cm to 7.5 cm pot seedling planted in spring, the SPAD value was higher under 0.5 g/L and 1.0 g/L fertilizer concentration treatment. The SPAD value gradually decreased following longer cultivation periods. The SPAD value of 10.5 cm pot seedling of four Phalaenopsis hybrids planted in spring was the lowest when using no fertilizer, but higher under 0.25 g/L and 0.5 g/L fertilizer concentration treatment. The 4.5 cm and 7.5 cm pot seedling growing media planted in spring and fall decreased its pH value following increasing fertilizer concentration and cultivation duration but still over 3.3; the EC value increased following higher fertilizer concentration. In detail, the highest EC value of other treatment groups kept between 2.0-3.0 mS/cm, except for 4.5 cm pot seedling planted in fall under 2.0 g/L fertilizer concentration treatment (over 8.0 mS/cm), but had no growth inhibition. In addition, to evaluate the sale rate from leaf number and leaf span, the result showed 4.5 cm pot seedling among four hybrids planted in spring, the other three could achieve 100% commercial sale rate under 1.0 g/L for 16 weeks, but Mini Red(Dtps. I-Hsin Helen ‘KHM69’) could achieve more than 80% sale rate under 0.5g/L and 1.0g/L fertilizer concentration treatment; besides, the 7.5 cm pot seedling of four hybrids could achieve more than 80% sale rate under 1.0g/L fertilizer concentration treatment for 12 weeks.

The orchid family covers 90 percent of the rarest plants under protection all over the world. The ecological and economic value of orchids has aroused public awareness. Since vegatitve propagation methods are available, development of in vitro methods are essential for conservation and commercialization of plants. Purposes work was elaboration progress of vegetative multiplication for tropical orchid Macodes petola in conditions in vitro. At research were proof 4 methods, which distinguish in using desinfection, in operating time and in using different nutritive mediums.