Academic literature on the topic 'Drought hypothesis'
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Journal articles on the topic "Drought hypothesis"
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Vargas, Jesús, and Pilar Paneque. "Challenges for the Integration of Water Resource and Drought-Risk Management in Spain." Sustainability 11, no. 2 (January 9, 2019): 308. http://dx.doi.org/10.3390/su11020308.
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Droughts are risks characterized by their complexity, uncertainty, and a series of other features, which differentiate them from other natural disasters and affect the strategies designed to manage them. These characteristics highlight the close relationship between drought management and water resources management. The following hypothesis is raised in this study—unsatisfactory integration of a drought-risk and water resources management strategies, increases the vulnerability to drought. To corroborate this hypothesis, the Spanish case was analyzed, where droughts are a recurrent phenomenon, due to the Mediterranean climate. Starting from the Intergovernmental Panel on Climate Change (IPCC) framework, which has been proposed to characterize vulnerability as a function of exposure, sensitivity, and adaptive capacity, this study analyzed the vulnerability in the Spanish River Basin Districts, through—(i) the integration of the predictable effects of climate change and the increased risk of exposure in hydrologic planning; (ii) the pressure on water resources that determines the sensitivity of the systems; and (iii) the development and implementation of drought management plans as a fundamental tool, in order to adapt before these events occur. The results showed that despite important advances in the process of conceiving and managing droughts, in Spain, there are still important gaps for an adequate integration of droughts risk into the water resource strategies. Therefore, despite the improvements, drought-risk vulnerability of the systems remained high.
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Leonard, Jenny, Adam G. West, Justin J. van Blerk, and Fernando Ojeda. "Does drought limit resprouter recruitment in Erica? A test using seeder and resprouter seedlings of Erica coccinea." Australian Journal of Botany 69, no. 8 (2021): 554. http://dx.doi.org/10.1071/bt21015.
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Context It has been proposed that the distribution of resprouter and seeder Erica in the Cape Floristic Region (CFR) of South Africa is determined by drought rather than by fire frequency. Seedlings of Erica seeders are predicted to withstand the mild droughts of the southwest CFR better than those of Erica resprouters, which would account for the abundance of seeders in this region. Aims This study aimed to test this hypothesis using Erica coccinea (L.), which contains both a resprouter and a seeder form. Methods One-year-old seedlings of both forms were subjected to a progressively severe 50-day drought in the greenhouse. Key results Contrary to expectations, seeder seedlings had 67% higher mortality than resprouters during the initial phase of drought (30% vs 18% after 32days). However, both forms were unable to survive as the drought progressed, resulting in 95% mortality by Day50. There were limited differences between the forms in gas exchange and water potential, and no difference in root:shoot ratios. However, resprouters had significantly higher soluble carbohydrates than did seeders, which may have aided in delaying mortality. Conclusions Our results showed no evidence of resprouter seedlings being more vulnerable to mild drought than seeders in E. coccinea. Implications Our findings challenge the hypothesis that the distribution of this species can be explained by the vulnerability of resprouter seedlings to mild drought.
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Evans, Bethany A., and Victoria A. Borowicz. "The plant vigor hypothesis applies to a holoparasitic plant on a drought-stressed host." Botany 93, no. 10 (October 2015): 685–89. http://dx.doi.org/10.1139/cjb-2015-0099.
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Parasitic plants extract resources from host vascular tissues but their responses to environmental fluctuation experienced by the host are poorly studied. Three frequently-cited hypotheses for effects of environmental stress on plant resistance to herbivores predict decreased, increased, or fluctuation in herbivore performance in response to drought stress. We tested which hypothesis best accounts for how drought stress applied to a perennial herb affects growth of the holoparasite, Cuscuta gronovii Willd. ex Roem. & Schult. (common dodder), an obligate shoot parasite. Verbesina alternifolia (L.) Britton ex Kearney (wingstem) supporting single, young C. gronovii were exposed to continuous, pulsed, or no water stress for 32 days and then dry mass of each parasite was determined. Consistent with the plant vigor hypothesis, C. gronovii grew significantly better on well-watered hosts. Continuous and pulsed drought stress of the host resulted in similar growth reduction relative to no drought stress. In addition to reducing absolute growth of the holoparasite, continuous and pulsed drought stress reduced the growth of the holoparasite relative to host growth. Although functionally similar to insect phloem feeders, growth of holoparasites such as C. gronovii is constrained by source–sink relations. Our results suggest drought stress experienced by a host weakens source strength and reduces uptake by the holoparasite acting as a sink.
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Stevenson, Samantha, Axel Timmermann, Yoshimitsu Chikamoto, Sally Langford, and Pedro DiNezio. "Stochastically Generated North American Megadroughts." Journal of Climate 28, no. 5 (February 26, 2015): 1865–80. http://dx.doi.org/10.1175/jcli-d-13-00689.1.
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Abstract The importance of interannual-to-decadal sea surface temperature (SST) influences on drought in the United States is examined using a suite of simulations conducted with the T31×3 resolution version of the NCAR Community Earth System Model (CESM1.0.3). The model captures tropical Pacific teleconnections to North American precipitation reasonably well, although orographic features are somewhat enhanced at higher resolution. The contribution of SST anomalies is isolated by comparing two idealized, 1000-yr CESM1.0.3 experiments: a fully coupled control and an atmosphere-only (CAM4) run forced with the SST climatology from the control. Droughts are identified using the Palmer Drought Severity Index (PDSI), which is computed over four U.S. regions from the CESM1.0.3 experiments and compared with the North American Drought Atlas (NADA). The CESM1.0.3 reproduces the persistence of NADA droughts quite well, although the model underestimates drought severity. Within the CESM1.0.3 framework, SST forcing does not significantly affect drought intensity or frequency of occurrence, even for very persistent “megadroughts” of 15 yr or more in length. In both the CESM1.0.3 and NADA, with the exception of the Southeast United States, droughts in all regions have intensities, persistence lengths, and occurrence frequencies statistically consistent with a red noise null hypothesis. This implies that SST forcing is not the dominant factor in generating drought and therefore that many decadal megadroughts are caused by a combination of internal atmospheric variability and coupling with the land surface, with SST anomalies playing only a secondary role.
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Kriger, Kerry M. "Lack of Evidence for the Drought-linked Chytridiomycosis Hypothesis." Journal of Wildlife Diseases 45, no. 2 (April 2009): 537–41. http://dx.doi.org/10.7589/0090-3558-45.2.537.
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Kuśmierek-Tomaszewska, Renata, and Jacek Żarski. "Assessment of Meteorological and Agricultural Drought Occurrence in Central Poland in 1961–2020 as an Element of the Climatic Risk to Crop Production." Agriculture 11, no. 9 (September 7, 2021): 855. http://dx.doi.org/10.3390/agriculture11090855.
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The results of numerous studies concerning meteorological drought show that there is a considerable impact of this phenomenon on several regions in Europe. On the other hand, statistical trends of dry spell occurrences in some areas of the continent are unclear or even negative. Therefore, further research should be directed towards a better understanding of this hazard, particularly the seasonal changes, in order to elaborate adequate strategies to prevent and mitigate its undesirable effects. The main goal of the work, conducted as part of the research strategy on contemporary climate change, was to confirm the hypothesis of increasing frequency and intensity of droughts during the period of active plant growth and development (May–August) in central Poland in 1961–2020. The prevailing rainfall conditions in this period determine the production and economic effects of agricultural output. The analysis covered a multiannual period, including two separate climate normals: 1961–1990 and 1991–2020. The work is also aimed at detecting relationships between indicators characterizing meteorological drought (the Standardized Precipitation Index—SPI) and agricultural drought (the actual precipitation deficiency—PAdef). It was found that the frequency of meteorological droughts in the studied period amounts to 30.0% (severe and extreme constitute 6.7%). No significant increase in the frequency and intensity of meteorological droughts over time was observed. Relationships between meteorological and agricultural drought indicators were significant, so the SPI can be considered an indicator of plant irrigation needs in the studied area.
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Chammakhi, Chaima, Alexandre Boscari, Marie Pacoud, Grégoire Aubert, Haythem Mhadhbi, and Renaud Brouquisse. "Nitric Oxide Metabolic Pathway in Drought-Stressed Nodules of Faba Bean (Vicia faba L.)." International Journal of Molecular Sciences 23, no. 21 (October 27, 2022): 13057. http://dx.doi.org/10.3390/ijms232113057.
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Drought is an environmental stress that strongly impacts plants. It affects all stages of growth and induces profound disturbances that influence all cellular functions. Legumes can establish a symbiosis with Rhizobium-type bacteria, whose function is to fix atmospheric nitrogen in organs called nodules and to meet plant nitrogen needs. Symbiotic nitrogen fixation (SNF) is particularly sensitive to drought. We raised the hypothesis that, in drought-stressed nodules, SNF inhibition is partly correlated to hypoxia resulting from nodule structure compaction and an increased O2 diffusion barrier, and that the nodule energy regeneration involves phytoglobin–nitric oxide (Pgb–NO) respiration. To test this hypothesis, we subjected faba bean (Vicia faba L.) plants nodulated with a Rhizobium laguerreae strain to either drought or osmotic stress. We monitored the N2-fixation activity, the energy state (ATP/ADP ratio), the expression of hypoxia marker genes (alcohol dehydrogenase and alanine aminotransferase), and the functioning of the Pgb–NO respiration in the nodules. The collected data confirmed our hypothesis and showed that (1) drought-stressed nodules were subject to more intense hypoxia than control nodules and (2) NO production increased and contributed via Pgb–NO respiration to the maintenance of the energy state of drought-stressed nodules.
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Wilschut, Rutger A., and Mark van Kleunen. "Drought alters plant‐soil feedback effects on biomass allocation but not on plant performance." Plant and Soil 462, no. 1-2 (February 10, 2021): 285–96. http://dx.doi.org/10.1007/s11104-021-04861-9.
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Abstract Aims Drought events can alter the composition of plant and soil communities, and are becoming increasingly common and severe due to climate change. However, how droughts affect plant-soil feedbacks is still poorly understood. Plants accumulate species-specific rhizosphere communities, and droughts may have varying impacts across plant species and soil biota. We therefore tested the hypothesis that drought alters plant-soil feedbacks differently among closely related plant species that differ in their preferences for soil moisture. Methods In a two-phase greenhouse experiment, we first conditioned grassland soil with seven Geranium species and, as controls, we conditioned soil with a grass species or left soil unplanted. In the second phase, we grew the Geranium species in conspecific, grass-conditioned and unplanted soil, maintained soil moisture at 5 %, 10 % or 20 % (w/w), and determined biomass responses after 35 days. Results Independent of conditioning, plants showed a weaker performance with decreasing soil moisture. Under the driest conditions, soil conditioning by conspecifics most negatively affected relative root weight in comparison to plants growing in unplanted control soil, while the effects of conspecific conditioning on relative root weights were species-specific when compared to plants grown in grass-conditioned control soil. Conclusions We conclude that decreased soil moisture modified plant-soil feedback effects on biomass allocation, and that these modifications acted in species-specific ways. However, drought effects on plant-soil feedbacks were subtle, and did not affect overall plant performance. Therefore, plant-soil feedback effects on plant performance during a drought event may be limited in comparison with the direct effects of drought.
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Hamzelou, Sara, Karthik Shantharam Kamath, Farhad Masoomi-Aladizgeh, Matthew M. Johnsen, Brian J. Atwell, and Paul A. Haynes. "Wild and Cultivated Species of Rice Have Distinctive Proteomic Responses to Drought." International Journal of Molecular Sciences 21, no. 17 (August 19, 2020): 5980. http://dx.doi.org/10.3390/ijms21175980.
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Drought often compromises yield in non-irrigated crops such as rainfed rice, imperiling the communities that depend upon it as a primary food source. In this study, two cultivated species (Oryza sativa cv. Nipponbare and Oryza glaberrima cv. CG14) and an endemic, perennial Australian wild species (Oryza australiensis) were grown in soil at 40% field capacity for 7 d (drought). The hypothesis was that the natural tolerance of O. australiensis to erratic water supply would be reflected in a unique proteomic profile. Leaves from droughted plants and well-watered controls were harvested for label-free quantitative shotgun proteomics. Physiological and gene ontology analysis confirmed that O. australiensis responded uniquely to drought, with superior leaf water status and enhanced levels of photosynthetic proteins. Distinctive patterns of protein accumulation in drought were observed across the O. australiensis proteome. Photosynthetic and stress-response proteins were more abundant in drought-affected O. glaberrima than O. sativa, and were further enriched in O. australiensis. In contrast, the level of accumulation of photosynthetic proteins decreased when O. sativa underwent drought, while a narrower range of stress-responsive proteins showed increased levels of accumulation. Distinctive proteomic profiles and the accumulated levels of individual proteins with specific functions in response to drought in O. australiensis indicate the importance of this species as a source of stress tolerance genes.
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Kuśmierek-Tomaszewska, Renata, Jacek Żarski, and Stanisław Dudek. "Assessment of Irrigation Needs in Sugar Beet (Beta vulgaris L.) in Temperate Climate of Kujawsko-Pomorskie Region (Poland)." Agronomy 9, no. 12 (November 28, 2019): 814. http://dx.doi.org/10.3390/agronomy9120814.
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The primary purpose of this work was to assess the need for irrigation in sugar beet cultivated in the temperate climate of the Kujawsko-Pomorskie region of Poland based on meteorological data from the period 1981–2010. The work was also aimed at determining the tendency of changes in the frequency and intensity of droughts during the period of high water needs for sugar beets (spanning July–August) and confirming the hypothesis that agricultural drought may be identified based on the indicator of meteorological drought—Standardized Precipitation Index (SPI). The occurrence of meteorological droughts amounted to 26.7–40.0%, depending on location. No significant trend of increasing dryness was found; however, quite the opposite, an upward tendency was identified, which indicates an improvement of precipitation conditions over time. It was found that sugar beet production in a temperate climate is carried out in the conditions of precipitation deficits, which amount to an average of 32–49 mm and a maximum of 112–173 mm in July–August, but the deficits showed neither significant nor targeted changes with time. A strong, significant relationship between meteorological (SPI) and agricultural (Pdef) drought indicators allows for a determination of sugar beet irrigation needs solely based on information on normalized precipitation values (SPI).
Dissertations / Theses on the topic "Drought hypothesis"
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Piccotto, Massimo. "Effetti degli NOx sulla fisiologia dei licheni foliosi epifiti." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3170.
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2007/2008L’obiettivo della ricerca è stato individuare i possibili effetti degli NOx, inquinanti aerodiffusi foto-ossidanti, sui licheni foliosi epifiti. Il lavoro è stato svolto con un particolare riguardo nell’individuare le modificazioni indotte a carico del processo fotosintetico del fotobionte lichenico attraverso metodi fluorimetrici. Le ricerche condotte hanno approfondito inizialmente alcuni aspetti metodologici, individuando, ad esempio, le variabili ambientali che influenzano maggiormente la capacità e l’efficienza fotosintetica di questi organismi. Successivamente, è stata disegnata una articolata sperimentazione, condotta mediante trapianti in siti urbani inquinati e non, che ha permesso di verificare gli effetti degli inquinanti aerodiffusi a concentrazioni ambientali in presenza di altri, naturali, fonti di disturbo. Questo lavoro dimostra, attraverso misure fisiologiche, che l’arido microclima urbano può essere un fattore limitante la fisiologia dei licheni e che la loro tolleranza agli NOx dipende strettamente dalla loro ecologia.
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Mason, Nicole Marie. "A test of the new variant famine hypothesis panel survey evidence from Zambia /." Diss., Connect to online resource - MSU authorized users, 2008.
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Otieno, Dennis O. "Coordinated tree responses to drought vulnerability and sustainable production ; hypotheses on arid ecosystem adjustments to limitations in water resources /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973199881.
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Isarangkool, Na Ayutthaya Supat. "Change of whole-tree transpiration of mature Hevea brasiliensis under soil and atmospheric droughts : analyze in intermittent and seasonal droughts under the framework of the hydraulic limitation hypothesis." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719009.
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Les variations de transpiration totale sous contraintes hydriques, à la fois atmosphérique et édaphique, sont étudiées pour des arbres matures d'Hevea brasiliensis (clone RRIM600) dans une zone limitée en eau du Nord-Est de la Thaïlande. Les variations sont analysées et comparées entre une sécheresse transitoire en saison des pluies et la sécheresse saisonnière caractérisée par des fluctuations de la surface foliaire (sénescence foliaire, chute des feuilles and re-feuillaison) et de la croissance racinaire en profondeur. Les réponses physiologiques sont analysées dans le cadre d'un modèle hydraulique simple appelé "RER_ET0". Ce modèle est principalement basé sur une valeur critique du potentiel hydrique foliaire (ψcrit) et sur les réponses, de la conductivité hydraulique totale de l'arbre (gL) et du potentiel hydrique de base (ψpredawn), à la disponibilité en eau du sol (REW). Une estimation précise et en continue de la transpiration totale des arbres durant une année complète était une mesure clé de cette étude avec des mesures concomitantes des conditions environnementales et du potentiel hydrique foliaire (ψLeaf). Nous avons appliqué la méthode à dissipation thermique transitoire (TTD) développée par Do et Rocheteau (2002b) qui a plusieurs avantages mais n'avait pas été testée sur bois d'hévéa. La méthode TTD a été calibrée en laboratoire sur des segments de branches d'Hevea brasiliensis et de deux autres espèces (Mangifera indica and Citrus maxima). Les résultats fournissent une calibration linéaire unique indépendante des espèces étudiées (R² = 0.88, n = 276, P<0.0001). Une comparaison en plantation via un bilan hydrique du sol en saison sèche valide les ordres de grandeurs de transpiration ainsi estimés par les flux de sève. Les résultats démontrent une remarquable saturation de la transpiration au dessus d'un certain seuil d'évapotranspiration de référence (ET0), environ 2.2 mm day-1, indépendamment de la disponibilité en eau du sol (REW). Ensuite, le dessèchement du sol en saison des pluies provoque une chute marquée de la transpiration en dessous d'un seuil de 50% du REW dans l'horizon de surface du sol, ce qui correspond à ψpredawn autour de -0.45 MPa. La transpiration est réduite de 40% à REW 0.3 et 80% à REW 0.1. La valeur minimale de potentiel hydrique foliaire (ψminimum) en journée ensoleillée ne décroit pas en fonction du dessèchement du sol mais est stable autour de -1.95 MPa ce qui suggère un comportement iso-hydrique. La décroissance de la transpiration est essentiellement liée à la variation de gL. Les résultats durant la sécheresse saisonnière montrent étonnamment que les principes du modèle à limitation hydraulique tiennent malgré les variations de phénologie et de surface foliaire. De plus, les variations phénologiques ont peu influencé sur les détails des paramètres et relations du modèle. Finalement, le cadre du simple modèle hydraulique a été suffisant pour décrire correctement les principales variations de transpiration de l'arbre sous contrainte hydrique édaphique comme climatique. Un comportement iso-hydrique des arbres matures étudiés est démontré à la fois par les résultats expérimentaux et la modélisation.
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Otieno, Dennis O. [Verfasser]. "Coordinated tree responses to drought : vulnerability and sustainable production ; hypotheses on arid ecosystem adjustments to limitations in water resources / Otieno Dennis O." 2004. http://d-nb.info/973199881/34.
Full textBooks on the topic "Drought hypothesis"
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Stahle, David W., Dorian J. Burnette, Daniel Griffin, and Edward R. Cook. Thirteenth Century AD. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199329199.003.0009.
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The hypothesis that a prolonged drought across southwestern North America in the late thirteenth century contributed to the abandonment of the region by Ancestral Pueblo populations, ultimately including the depopulation of the Mesa Verde region, continues to be a focus of archaeological research in the Pueblo region. We address the hypothesis through the re-measurement of tree-ring specimens from living trees and archaeological wood at Mesa Verde, Colorado, to derive chronologies of earlywood, latewood, and total ring width. The three chronology types all date from AD 480 to 2008 and were used to separately reconstruct cool and early warm season effective moisture and total water-year precipitation for Chapin Mesa near many of the major prehistoric archaeological sites. The new reconstructions indicate three simultaneous cool and early growing season droughts during the twelfth and thirteenth centuries that may have contributed to the environmental and social factors behind Ancestral Pueblo migrations over this sector of the Colorado Plateau. These sustained inter-seasonal droughts included the “Great Drought” of the late-thirteenth century, which is estimated to have been one of the most severe regimes of cool and early summer drought in the last 1,500-years and coincided with the end of Puebloan occupations at Mesa Verde. The elevation of the 30 cm isohyet of water-year precipitation reconstructed for southwestern Colorado from the new ring-width data is mapped from AD 1276–1280 and identifies areas where dry-land cultivation of maize may not have been practical during the driest years of the Great Drought. There is no doubt about the exact dating of the tree-ring chronologies, but the low sample size of dated specimens from Mesa Verde during the late-thirteenth and fourteenth centuries contributes uncertainty to these environmental reconstructions at the time of abandonment.
Book chapters on the topic "Drought hypothesis"
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Boersma, L., Yongsheng Feng, and Xiaomei Li. "Osmotic Adjustment in Plant Cells Exposed to Drought and Temperature Stress: Can a Cause and Effect Hypothesis be Formulated and Tested?" In Mechanics of Swelling, 143–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-84619-9_6.
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Malyse, Majoumo Christelle. "Rainfall Variability and Adaptation of Tomatoes Farmers in Santa: Northwest Region of Cameroon." In African Handbook of Climate Change Adaptation, 699–711. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_138.
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AbstractThe Santa agrarian basin being one of the main market gardening basins in Cameroon and one of the producers of tomatoes in the country is vulnerable to the impact of rainfall variability. The spatiotemporal variability of rainfall through the annual, monthly, and daily fluctuations has greatly affected the market gardening sector in general and tomatoes production in particular. Thus, given rise to the research topic “Rainfall variability and adaptation of tomatoes farmers in Santa North west region of Cameroon,” its principal objective is to contribute to better understanding of the recent changes occurring in tomatoes production and productivity in Santa. To attain this objective, a principal hypothesis was formulated that rainfall variability instead of unnatural conditions or human constraints justifies changes observed in tomatoes production in Santa and resulting adaptation strategies developed by peasants and stakeholders.Our study came out with several findings, among which includes rainfall events in Santa fluctuate in time and in space with reduction in the number of rainy day and increase in the intensity of rainfall events causing soil erosion, infertility, and frequent crop diseases, insects, and pests. Extreme events such as drought and flooding have equally become frequent in the area especially during the different cycles of tomatoes production disrupting the agricultural calendar and causing crop failure and decrease in yields with Pearson’s correlation of 0.017. This positive value shows that there is a relationship between annual rainfall and tomatoes output in Santa. Tomatoes farmers in Santa are struggling to adapt locally to this situations, but their efforts are still limited especially due to their low level of education and poverty. Finally, it was seen that the output of tomatoes over the years in Santa has a strong correlation with rainfall. Based on the findings of this study, the government is called upon to assist farmers in their adaptation options.
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"Situating Urban Drought Resilience." In Sustainability, edited by Lawrence Baker, 124–46. NYU Press, 2018. http://dx.doi.org/10.18574/nyu/9781479894567.003.0006.
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Cities around the world are experiencing greater water stress as the result of growing urban populations, increasing per capita wealth (and water use), and climate change. This chapter examines the concept urban drought resilience. The central hypothesis of this chapter is that the resilience of cites to future droughts can be understood based on socio-ecological characteristics, including biophysical, economic, and social factors. I hypothesize that resilience to urban drought can be predicted by the antecedent hydrologic condition, the polycentric aspects of governance, and the capacity of governance, both to provide feedback for adaptation and to respond. I propose a research agenda to understand urban drought resilience and to create tools that cities can use to increase this resilience. Among these are actionable metrics of urban drought resilience, analogous to widely used economic metrics used by governments to manage economic conditions, including metrics of equity as well as system-level metrics of hydrologic condition.
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"Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques." In Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques, edited by Gary D. Grossma, Robert E. Ratajczak, Mark D. Farr, C. Michael Wagner, and J. Todd Petty. American Fisheries Society, 2010. http://dx.doi.org/10.47886/9781934874141.ch4.
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<em>Abstract</em>.—Studies demonstrating the mechanisms regulating biodiversity are uncommon. Streams and rivers worldwide display a longitudinal gradient in fish biodiversity, and most prior research has used correlative evidence to infer that higher downstream diversity is produced by factors facilitating greater niche separation. We combine 20 years of fish abundance samples from a representative southern Appalachian stream with critical swimming velocity experiments to provide direct evidence that a shifting hydrodynamic barrier affects this gradient in Coweeta Creek. We observed increased diversity in multiple sites, produced by species immigrating upstream during periodic droughts (1985–1988, 1999–2002) and a highly significant positive relationship (<em>r<sup></em>2</sup> = 0.77) between drought (Palmer index) and Shannon-Weiner diversity. Resident fish generally had smaller standard lengths during drought periods. Critical velocity measurements showed that residents could tolerate faster water velocities than drought immigrants and that upstream velocities in nondrought years were faster than those in some downstream sites. These data support the hypothesis that local fish diversity in this system is limited by the ability of drought immigrants to pass an upstream hydrodynamic barrier. Alternative hypotheses such as temperature differences between sites, increased capture efficiency during droughts, and increased productivity during droughts were not supported by the data. The relationship between drought and diversity in this system is counterintuitive because drought should reduce resource availability and produce lower rather than higher diversity. These results highlight the important relationship between natural flow variation and maintenance of local diversity and demonstrate the need for long-term ecological data.
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L. Nelson, Suzanne, Nicola Justice, Kaitlynn M. Apple, Aidan H. Liddiard, Madeleine R. Elias, and Jon D. Reuter. "Changes to Health Parameters of White-Tailed Deer during a Drought in the US Virgin Islands." In Tropical Forests - Ecology, Diversity and Conservation Status [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.108270.
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Resident white-tailed deer (Odocoileus virginianus) on St. John, US Virgin Islands offer a unique case study for understanding a population under pressure from climate change. During a 2015–2016 regional drought, deer health parameters including body condition, coat condition, tick prevalence, musculature, and stress hormones were tracked over three field seasons representing the onset, peak, and recovery phases of the drought. All health indicators showed significant change over the course of the drought, and post-hoc tests suggest some indicators (body condition, musculature, and ticks) were more sensitive during drought onset. High levels of cortisol during the peak period indicated substantial stress to the population, which normalized during recovery. The strongest correlations were between overall health/body condition and musculature and overall health/body condition and coat condition. The weakest correlations were between ticks and the remaining three variables. These results support the hypothesis that various measures of deer health are related. The frequency and intensity of droughts and environmental stressors are predicted to increase in the future due to climate change, which will further challenge this island deer population.
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"Modelling of last hypothesis of climate change impacts on water resources in Sierra de las Cabras aquifer (Southern Spain)." In Drought: Research and Science-Policy Interfacing, 73–80. CRC Press, 2015. http://dx.doi.org/10.1201/b18077-12.
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"Anadromous Sturgeons: Habitats, Threats, and Management." In Anadromous Sturgeons: Habitats, Threats, and Management, edited by John W. McCord, Mark R. Collins, William C. Post, and Theodore I. J. Smith. American Fisheries Society, 2007. http://dx.doi.org/10.47886/9781888569919.ch23.
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<em>Abstract</em>.—The anadromous Atlantic sturgeon <em>Acipenser oxyrinchus</em> once supported an important commercial fishery throughout its range (northern Florida, USA, to Labrador, Canada). All surviving populations are apparently depleted, presumably due to overfishing, pollution, and dam construction. A complete moratorium on the fishery has been established in U.S. waters. Unfortunately, population status is unknown for nearly all systems. Several 1994–2001 data sets from South Carolina rivers were examined for their potential in development of recruitment (year-class abundance) indices. Because Atlantic sturgeon often begin leaving their natal systems at age 2, after which they occupy other systems and then presumably return to natal areas at sexual maturity several years later, a valid river-specific abundance index must be based on either age0–1 or adult fish. Working with three former commercial Atlantic sturgeon fishermen to collect adults in two rivers during the spring and fall of 1998 resulted in collection of only 39 fish in 13 nominal age-classes. In another river, 2 years of monthly sampling with multipanel, anchored gill nets and otter trawls at eight stations throughout the estuary produced only 31 juvenile Atlantic sturgeon. Neither of these study designs provided adequate sample sizes. However, sampling in a clean-bottom section at the freshwater–brackish water interface of the Edisto River with a modified drift gill net produced large numbers of small Atlantic sturgeon. More than 3,000 juveniles have been collected and tagged since 1994. The 1,331 nominal age-1 Atlantic sturgeon that were captured displayed a distinct bimodal length frequency distribution, supporting the hypothesis that there are both spring and fall spawning events. A period of record drought impeded sampling efforts during a portion of this study. However, when flows and bottom configurations allow nets to be fished at the freshwater–brackish water interface, the gears and methods employed in the Edisto River can produce an age-1 Atlantic sturgeon catch per unit effort that is high enough to be used in estimating relative year-class strength.
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Lockwood, Alan H. "Violence, Conflict, and Societal Disruption." In Heat Advisory. The MIT Press, 2016. http://dx.doi.org/10.7551/mitpress/9780262034876.003.0008.
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Diverse studies of traffic, baseball, crime-temperature relationships, and others, support the hypothesis that heat breeds violence at a time when, in the US, violent crime is on the wane. Droughts and deluges lead to environmental insecurity by many mechanisms as reflected in an examination of social conflicts in Africa. Rising food prices also foster riots. Climate change is an important factor that has led to societal collapse. Other weather and climate changes, such as those associated with El Niño, are also linked to societal disruption. These relationships have contributed to the current violence in the Middle East.
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Hayden, Bruce P., and Nils R. Hayden. "Decadal and Century-Long Changes in Storminess at Long-Term Ecological Research Sites." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0026.
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Ecological disturbances at Long-Term Ecological Research (LTER) sites are often the result of extreme meteorological events. Among the events of significance are tropical storms, including hurricanes, and extratropical cyclones. Extratropical storms are low-pressure systems of the middle and high latitudes with their attendant cold and warm fronts. These fronts are associated with strong, horizontal thermal gradients in surface temperatures, strong winds, and a vigorous jet stream aloft. These storms and their attendant fronts generate most of the annual precipitation in the continental United States and provide the lifting mechanisms for thunderstorms that, on occasion, spawn tornadoes. Off the United States West and East Coasts, extratropical storms generate winds, wind waves, wind tides, and long-shore currents that rework coastal sediments, alter landscape morphology, and change the regional patterns of coastal erosion and accretion (Dolan et al. 1988). Although extratropical storms do not match hurricanes in either precipitation intensity or in the strength of the winds generated, they are much larger in size and have a more extensive geographic impact. On occasion, extratropical storms will intensify at an extraordinary rate of 1 millibar (mb) per hour for 24 hours or more. Such storms are classed as “bomb” and are comparable to hurricanes. Extratropical storms occur in all months of the year but are most frequent and more intense in winter when the north-south temperature contrast is large and dynamic support for storm intensification from the stronger jet stream aloft is great. In this chapter, we will explore the history of storminess for those LTER sites in the continental United States at which more than a century of data on storms and their storm tracks are readily available. Specifically, we will look at the record of changes in storminess at both the regional and national scales. During the 1990s, significant storms along the U.S. West Coast and droughts and fires in Florida in an El Niño year led to a hypothesis that El Niño and La Niña conditions were associated with a modulation in the frequency of storms. In addition, it has been suggested that the frequency of El Niño and La Niña events and, by inference, storminess, has increased during the past century.
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David, Greenland, and Douglas G. Goodin. "Climate Variability and Ecosystem Response—Synthesis." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0039.
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At the outset we identified the theme of this book as how ecosystems respond to climate variability. We have examined this theme at a variety of LTER sites and at a variety of timescales. The subject matter of the book was also to be focused on a series of framework questions. We noted that the theme of climate variability and ecosystem response is inherently deterministic and implicitly carries with it the notion of climate cause and ecosystem result. The analyses in this volume demonstrated that this is a valid and fruitful working assumption. However, the idea of a simple single climate cause and effect might be true in some cases, but it is obviously simplistic. More realistically, the effects of climate variability cascade through ecosystems. In almost all cases there is the probability of many secondary and associated effects accompanying the primary effects. As an example, the possible results of potential warming in the Pacific Northwest forests include changes in global carbon dioxide input, nutrient cycling between the plants and the soil, and feedback links between the plant and soil organisms (Perry and Borchers 1990). In general there seem to be at least three broad classes of interaction between climate and ecosystems. First, the ecosystem simply responds to individual climate events or episodes that exceed some threshold for response. Second, ecosystems may buffer climate variability. In this sense they are filtering the effect of the climate event or episode. The same component in an ecosystem can sometimes act as a buffer and sometimes not, according to the nature of the climate event. Thus a riparian environment might provide soil moisture that acts as a buffer to a drought, but the whole environment might be destroyed by a large flood event. Third, we hypothesize that the ecosystem may move into resonance with the climate variability with positive and negative feedbacks that produce a strong ecosystem response. The relationship between fire and the Southern Oscillation indicates that the South west United States (Swetnam and Betancourt 1990) may provide an example of such resonance. Other examples of resonance, discussed subsequently, may exist in the forests of Interior Alaska and Puerto Rico. If there is indeed an ecosystem response to climate variability, the response tends to occur in cascades.
Conference papers on the topic "Drought hypothesis"
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KUŚMIEREK-TOMASZEWSKA, Renata, Stanisław DUDEK, and Jacek ŻARSKI. "DETECTION OF CHANGE IN DROUGHT FREQUENCY IN BYDGOSZCZ REGION, CENTRAL POLAND." In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.030.
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The aim of the work, carried out within the framework of research on currently occurring rather than predicted climate changes, was to confirm or deny the hypothesis of increasing incidence of droughts in central Poland (the Bydgoszcz region) over the years 1986-2015. According to projections of climate change, the variability and extremity of weather conditions are expected to increase. In studies conducted under some climate scenarios, it was shown that atmospheric precipitation variability in central Poland will increase even to 20%, depending on the scenario. Some researches indicate that these changes are already taking place. The material was the data of precipitation measurements gained from weather station, located in a poorly urbanized area, at the Research Center of the University of Science and Technology. Totals of atmospheric precipitation in the 30-year period were analyzed (1986-2015). Dry periods in individual months, seasons, half-years and entire years were identified on the basis of the relative precipitation index (RPI). The precipitation totals in the years 1986-2015 were characterized by a very high temporal variability and thus increased the climatic risk of plants cultivation. The significant positive trend of precipitation totals was found only for the cold half-year, which is consistent with the projections of the IPCC report. The frequency of the occurrence dry months was 38.6%, of seasons 38.3%, half-years 35.0% and years 30.0%. There was noted no increasing frequency of dry periods with years; just to the contrary, a decreasing tendency was identified.
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PIVORAS, Ainis, Marius MIKALAJŪNAS, Diana JUONYTĖ, and Gintaras PIVORAS. "INTEGRATED EFFECT OF CLIMATE AND AIR POLLUTANTS ON DIURNAL TREE RING FORMATION OF SCOTS PINE, NORWAY SPRUCE AND SILVER AND DOWNY BIRCH TREES STEM CIRCUMFERENCE." In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.099.
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The integrated effect of climatic and other abiotic stress factors including surface ozone on diurnal tree ring width formation of the prevailing in Lithuania tree species as the main response parameter of tree capacity to adapt to and mitigate the recent global changes was investigated. The obtained data revealed that Norway spruce is better adapted to recent climatic conditions in temperate forest than birch trees. Even during the drought episode spruce stem increment exceeded increment of the rest of considered tree species. Silver and Downy birch tree reactions revealed the lowest sensitivity of these tree species not only to unfavorable environmental factors but also to favorable factors which should stimulate tree growth intensity. This is why the growth intensity of this tree species recently has been gradually decreasing. The hypothesis that the coniferous species are more adaptive to recent climate changes was confirmed. The study is based on the results obtained conducting national project supported by Lithuanian Council of Research “FOREstRESS” (SIT- 3/2015).
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Yadav, Abhishek, Ashok K. Das, Janet K. Allen, and Farrokh Mistree. "A Computational Framework to Support Social Entrepreneurs in Creating Value for Rural Communities in India." In ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-97375.
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Abstract Over 250 million people in India currently lack access to basic services needed to live a rudimentary lifestyle. Most of these people reside in rural parts of the country. Lack of employment, economic opportunities, and development in rural areas are foundational to low socio-economic levels in these communities. Added to this are environmental issues such as natural resource depletion, yearlong droughts, climate change. We hypothesize that social enterprises developed at the community level can improve the quality of life of people in rural India. The lack of access to investment and resources to identify and develop social enterprises are major challenges for the creation of social enterprises. We hypothesize that a successful partnership between two major stakeholders, namely, social entrepreneurs and corporate social responsibility (CSR) investors is the key in developing multiple social enterprises to foster rural development. However, CSR and other investors require quantitative information along with impact evaluation of the value proposition before investing. Social entrepreneurs lack tools to develop and present value propositions for the village in a quantitative form. In this paper, we propose a computational framework to fill this gap and to facilitate dialog between CSR investors and social entrepreneurs that may result in a mutually favorable investment.
Reports on the topic "Drought hypothesis"
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Barg, Rivka, Kendal D. Hirschi, Avner Silber, Gozal Ben-Hayyim, Yechiam Salts, and Marla Binzel. Combining Elevated Levels of Membrane Fatty Acid Desaturation and Vacuolar H+ -pyrophosphatase Activity for Improved Drought Tolerance. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7613877.bard.
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Background to the topic: In previous works we have shown that Arabidopsis and tomato over-expressing H+-pyrophosphatase show increased tolerance to drought imposed by withholding irrigation of young plants in pots (Park et al. 2005). In addition, young tobacco plants over-expressing fatty acid desaturase 3 (OEX-FAD3) also showed increasing tolerance to drought stress (Zhang et al 2005), and similarly OEX-FAD3 young tomato plants (unpublished data from ARO), hence raising the possibility that pyramiding the two could further improve drought tolerance in tomato. Based on these findings the specific objects originally set were: 1. To analyze the impact of pyramiding transgenes for enhanced fatty acid desaturation and for elevated H+-PPase activity on tomato yielding under water deficit stress conditions. 2. To elucidate the biochemical relationship between elevated desaturation of the membrane lipids and the activities of selected vacuolar transporters in the context of drought responses. 3. To explore the S. pennellii introgression lines as alternative genetic sources for drought tolerance related to enhanced fatty acid desaturation and/or H+-PPase activity. 4. Since OEX-FAD3 increases the levels of linolenic acid which is the precursor of various oxylipins including the stress hormone Jasmonate. (JA), study of the effect of this transgene on tolerance to herbivore pests was added as additional goal. The Major conclusions, solutions, and achievements are: (1) The facts that ectopic over-expression of vacuolarH+-PPases (in line OEX-AVP1) does not change the fatty acid profile compared to the parental MoneyMaker (MM) line and that elevated level of FA desaturation (by OEX-FAD3) does not change the activity of either H+-PPase, H+-ATPaseor Ca2+ /H+ antiport, indicate that the observed increased drought tolerance reported before for increase FA desaturation in tobacco plants and increased H+PPase in tomato plants involves different mechanisms. (2) After generating hybrid lines bringing to a common genetic background (i.e. F1 hybrids between line MP-1 and MM) each of the two transgenes separately and the two transgenes together the effect of various drought stress regimes including recovery from a short and longer duration of complete water withhold as well as performance under chronic stresses imposed by reducing water supply to 75-25% of the control irrigation regime could be studied. Under all the tested conditions in Israel, for well established plants grown in 3L pots or larger, none of the transgenic lines exhibited a reproducible significantly better drought tolerance compare to the parental lines. Still, examining the performance of these hybrids under the growth practices followed in the USA is called for. (3) Young seedlings of none of the identified introgression lines including the S. pennellii homologs of two of the H+-PPase genes and one of the FAD7 genes performed better than line M82 upon irrigation withhold. However, differences in the general canopy structures between the IL lines and M82 might mask such differences if existing. (4). Over-expression of FAD3 in the background of line MP-1 was found to confer significant tolerance to three important pest insects in tomato: Bordered Straw (Heliothis peltigera), Egyptian cotton leafworm (Spodoptera littoralis) and Western Flower Thrips (Frankliniella occidentalis). Implications: Although the original hypothesis that pyramiding these two trasgenes could improve drought tolerance was not supported, the unexpected positive impact on herbivore deterring, as well as the changes in dynamics of JA biosynthesis in response to wounding and the profound changes in expression of wound response genes calls for deciphering the exact linolenic acid derived signaling molecule mediating this response. This will further facilitate breeding for herbivore pest and mechanical stress tolerance based on this pathway.
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Granot, David, Scott Holaday, and Randy D. Allen. Enhancing Cotton Fiber Elongation and Cellulose Synthesis by Manipulating Fructokinase Activity. United States Department of Agriculture, 2008. http://dx.doi.org/10.32747/2008.7613878.bard.
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a. Objectives (a) Identification and characterization of the cotton fiber FRKs; (b) Generating transgenic cotton plants overproducing either substrate inhibited tomato FRK or tomato FRK without substrate inhibition; (c) Generating transgenic cotton plants with RNAi suppression of fiber expressed FRKs; (d) Generating Arabidopsis plants that over express FRK1, FRK2, or both genes, as additional means to assess the contribution of FRK to cellulose synthesis and biomass production. b. Background to the topic: Cellulose synthesis and fiber elongation are dependent on sugar metabolism. Previous results suggested that FRKs (fructokinase enzymes that specifically phosphorylate fructose) are major players in sugar metabolism and cellulose synthesis. We therefore hypothesized that increasing fructose phosphorylation may enhance fiber elongation and cellulose synthesis in cotton plants. Accordinlgy, the objectives of this research were: c. Major conclusions and achievements: Two cotton FRKs expressed in fibers, GhFRK2 and GhFRK3, were cloned and characterized. We found that GhFRK2 enzyme is located in the cytosol and GhFRK3 is located within plastids. Both enzymes enable growth on fructose (but not on glucose) of hexose kinase deficient yeast strain, confirming the fructokinase activity of the cloned genes. RNAi constructs with each gene were prepared and sent to the US collaborator to generate cotton plants with RNAi suppression of these genes. To examine the effect of FRKs using Arabidopsis plants we generated transgenic plants expressing either LeFRK1 or LeFRK2 at high level. No visible phenotype has been observed. Yet, plants expressing both genes simultaneously are being created and will be tested. To test our hypothesis that increasing fructose phosphorylation may enhance fiber cellulose synthesis, we generated twenty independent transgenic cotton plant lines overexpressing Lycopersicon (Le) FRK1. Transgene expression was high in leaves and moderate in developing fiber, but enhanced FRK activity in fibers was inconsistent between experiments. Some lines exhibited a 9-11% enhancement of fiber length or strength, but only one line tested had consistent improvement in fiber strength that correlated with elevated FRK activity in the fibers. However, in one experiment, seed cotton mass was improved in all transgenic lines and correlated with enhanced FRK activity in fibers. When greenhouse plants were subjected to severe drought during flowering and boll development, no genotypic differences in fiber quality were noted. Seed cotton mass was improved for two transgenic lines but did not correlate with fiber FRK activity. We conclude that LeFRK1 over-expression in fibers has only a small effect on fiber quality, and any positive effects depend on optimum conditions. The improvement in productivity for greenhouse plants may have been due to better structural development of the water-conducting tissue (xylem) of the stem, since stem diameters were larger for some lines and the activity of FRK in the outer xylem greater than observed for wild-type plants. We are testing this idea and developing other transgenic cotton plants to understand the roles of FRK in fiber and xylem development. We see the potential to develop a cotton plant with improved stem strength and productivity under drought for windy, semi-arid regions where cotton is grown. d. Implications, scientific and agricultural: FRKs are probably bottle neck enzymes for biomass and wood synthesis and their increased expression has the potential to enhance wood and biomass production, not only in cotton plants but also in other feed and energy renewable plants.
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Miller, Gad, and Jeffrey F. Harper. Pollen fertility and the role of ROS and Ca signaling in heat stress tolerance. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598150.bard.
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The long-term goal of this research is to understand how pollen cope with stress, and identify genes that can be manipulated in crop plants to improve reproductive success during heat stress. The specific aims were to: 1) Compare heat stress dependent changes in gene expression between wild type pollen, and mutants in which pollen are heat sensitive (cngc16) or heat tolerant (apx2-1). 2) Compare cngc16 and apx2 mutants for differences in heat-stress triggered changes in ROS, cNMP, and Ca²⁺ transients. 3) Expand a mutant screen for pollen with increased or decreased thermo-tolerance. These aims were designed to provide novel and fundamental advances to our understanding of stress tolerance in pollen reproductive development, and enable research aimed at improving crop plants to be more productive under conditions of heat stress. Background: Each year crop yields are severely impacted by a variety of stress conditions, including heat, cold, drought, hypoxia, and salt. Reproductive development in flowering plants is highly sensitive to hot or cold temperatures, with even a single hot day or cold night sometimes being fatal to reproductive success. In many plants, pollen tube development and fertilization is often the weakest link. Current speculation about global climate change is that most agricultural regions will experience more extreme environmental fluctuations. With the human food supply largely dependent on seeds, it is critical that we consider ways to improve stress tolerance during fertilization. The heat stress response (HSR) has been intensively studied in vegetative tissues, but is poorly understood during reproductive development. A general paradigm is that HS is accompanied by increased production of reactive oxygen species (ROS) and induction of ROS-scavenging enzymes to protect cells from excess oxidative damage. The activation of the HSR has been linked to cytosolic Ca²⁺ signals, and transcriptional and translational responses, including the increased expression of heat shock proteins (HSPs) and antioxidative pathways. The focus of the proposed research was on two mutations, which have been discovered in a collaboration between the Harper and Miller labs, that either increase or decrease reproductive stress tolerance in a model plant, Arabidopsis thaliana (i.e., cngc16--cyclic nucleotide gated channel 16, apx2-1--ascorbate peroxidase 2,). Major conclusions, solutions, achievements. Using RNA-seq technology, the expression profiles of cngc16 and apx2 pollen grains were independently compared to wild type under favourable conditions and following HS. In comparison to a wild type HSR, there were 2,776 differences in the transcriptome response in cngc16 pollen, consistent with a model in which this heat-sensitive mutant fails to enact or maintain a normal wild-type HSR. In a comparison with apx2 pollen, there were 900 differences in the HSR. Some portion of these 900 differences might contribute to an improved HSR in apx2 pollen. Twenty-seven and 42 transcription factor changes, in cngc16 and apx2-1, respectively, were identified that could provide unique contributions to a pollen HSR. While we found that the functional HS-dependent reprogramming of the pollen transcriptome requires specific activity of CNGC16, we identified in apx2 specific activation of flavonol-biosynthesis pathway and auxin signalling that support a role in pollen thermotolerance. Results from this study have identified metabolic pathways and candidate genes of potential use in improving HS tolerance in pollen. Additionally, we developed new FACS-based methodology that can quantify the stress response for individual pollen in a high-throughput fashion. This technology is being adapted for biological screening of crop plant’s pollen to identify novel thermotolerance traits. Implications, both scientific and agricultural. This study has provided a reference data on the pollen HSR from a model plant, and supports a model that the HSR in pollen has many differences compared to vegetative cells. This provides an important foundation for understanding and improving the pollen HSR, and therefor contributes to the long-term goal of improving productivity in crop plants subjected to temperature stress conditions. A specific hypothesis that has emerged from this study is that pollen thermotolerance can be improved by increasing flavonol accumulation before or during a stress response. Efforts to test this hypothesis have been initiated, and if successful have the potential for application with major seed crops such as maize and rice.
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LaBonte, Don, Etan Pressman, Nurit Firon, and Arthur Villordon. Molecular and Anatomical Characterization of Sweetpotato Storage Root Formation. United States Department of Agriculture, December 2011. http://dx.doi.org/10.32747/2011.7592648.bard.
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Original objectives: Anatomical study of storage root initiation and formation. Induction of storage root formation. Isolation and characterization of genes involved in storage root formation. During the normal course of storage root development. Following stress-induced storage root formation. Background:Sweetpotato is a high value vegetable crop in Israel and the U.S. and acreage is expanding in both countries and the research herein represents an important backstop to improving quality, consistency, and yield. This research has two broad objectives, both relating to sweetpotato storage root formation. The first objective is to understand storage root inductive conditions and describe the anatomical and physiological stages of storage root development. Sweetpotato is propagated through vine cuttings. These vine cuttings form adventitious roots, from pre-formed primordiae, at each node underground and it is these small adventitious roots which serve as initials for storage and fibrous (non-storage) “feeder” roots. What perplexes producers is the tremendous variability in storage roots produced from plant to plant. The marketable root number may vary from none to five per plant. What has intrigued us is the dearth of research on sweetpotato during the early growth period which we hypothesize has a tremendous impact on ultimate consistency and yield. The second objective is to identify genes that change the root physiology towards either a fleshy storage root or a fibrous “feeder” root. Understanding which genes affect the ultimate outcome is central to our research. Major conclusions: For objective one, we have determined that the majority of adventitious roots that are initiated within 5-7 days after transplanting possess the anatomical features associated with storage root initiation and account for 86 % of storage root count at 65 days after transplanting. These data underscore the importance of optimizing the growing environment during the critical storage root initiation period. Water deprivation during this phenological stage led to substantial reduction in storage root number and yield as determined through growth chamber, greenhouse, and field experiments. Morphological characterization of adventitious roots showed adjustments in root system architecture, expressed as lateral root count and density, in response to water deprivation. For objective two, we generated a transcriptome of storage and lignified (non-storage) adventitious roots. This transcriptome database consists of 55,296 contigs and contains data as regards to differential expression between initiating and lignified adventitious roots. The molecular data provide evidence that a key regulatory mechanism in storage root initiation involves the switch between lignin biosynthesis and cell division and starch accumulation. We extended this research to identify genes upregulated in adventitious roots under drought stress. A subset of these genes was expressed in salt stressed plants.