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Caracterização fisiológica e perfil de expressão gênica de cultivares de cana-de-açúcar (Saccharum spp) contrastantes para o deficit hídrico; Physiological characterization and gene expression profiling of sugarcane (Saccharum spp) genotypes contrasting for drought tolerance

Oliveira, João Felipe Nebó Carlos de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/02/2013 PT
Relevância na Pesquisa
37.12%
A cana-de-açúcar (Saccharum spp.) é uma das culturas mais importantes para a economia brasileira, fonte de matéria-prima para produção de açúcar e álcool. O setor sucroalcoleiro tem expandido rapidamente devido à alta demanda por biocombustíveis. Para atender tal demanda e garantir a produção de açúcar, a área cultivada deverá ser expandida utilizando áreas de cerrado e pastagens degradadas no Sudeste e Centro-Oeste, caracterizadas por invernos secos com períodos de deficiência hídrica acentuada. Cultivares com tolerância a seca e alto potencial produtivo nessas regiões são desejadas para esta expansão, e a elucidação das bases moleculares e fisiológicas da tolerância é indispensável para o desenvolvimento de tais cultivares. Para investigar mecanismos fisiológicos e moleculares envolvidos na tolerância à seca metodologias baseadas em ensaios de campo e casa de vegetação foram avaliadas, com foco na fenotipagem e perfil de expressão gênica. O uso de polietilenoglicol (PEG) como agente estressor na solução de plantas hidropônicas foi avaliado para simulação da seca, bem como a avaliação do vazamento de eletrólitos após exposição ao Paraquat (methyl-viologen). Dois genótipos previamente selecionados com base no comportamento contrastante para resposta a seca foram utilizados para testar a hipótese dos mecanismos por trás da tolerância em cana...

Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal

Paulo, A.A.; Rosa, R.D.; Pereira, L.S.
Fonte: European Geisciences Union Publicador: European Geisciences Union
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
37.04%
Distinction between drought and aridity is crucial to understand water scarcity processes. Drought indices are used for drought identification and drought severity characterisation. The Standardised Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are the most known drought indices. In this study, they are compared with the modified PDSI for Mediterranean conditions (MedPDSI) and the Standardised Precipitation Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance of an olive crop, thus real evapotranspiration is considered, while SPEI uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can be computed at various time scales. Aiming at understanding possible impacts of climate change, prior to compare the drought indices, a trend analysis relative to precipitation and temperature in 27 weather stations of Portugal was performed for the period 1941 to 2006. A trend for temperature increase was observed for some weather stations and trends for decreasing precipitation in March and increasing in October were also observed for some locations. Comparisons of the SPI and SPEI at 9- and 12-month time scales, the PDSI and Med- PDSI were performed for the same stations and period. SPI and SPEI produce similar results for the same time scales concerning drought occurrence and severity. PDSI and Med- PDSI correlate well between them and the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe droughts than SPI or SPEI and identify drought occurrence earlier than these indices. This behaviour is likely to be related with the fact that a water balance is performed with PDSI and MedPDSI...

Are drought occurrence and severity aggravating ? A study on SPI drought class transitions using log-linear models and ANOVA-like inference

Moreira, E.E.; Mexia, J.T.; Pereira, L.S.
Fonte: European Geosciences Union Publicador: European Geosciences Union
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
37.04%
Abstract. Long time series (95 to 135 yr) of the 12-month time scale Standardized Precipitation Index (SPI) relative to 10 locations across Portugal were studied with the aim of investigating if drought frequency and severity are changing through time. Considering four drought severity classes, time series of drought class transitions were computed and later divided into several sub-periods according to the length of SPI time series. Drought class transitions were calculated to form a 2-dimensional contingency table for each sub-period, which refer to the number of transitions among drought severity classes. Two-dimensional log-linear models were fitted to these contingency tables and an ANOVA-like inference was then performed in order to investigate differences relative to drought class transitions among those subperiods, which were considered as treatments of only one factor. The application of ANOVA-like inference to these data allowed to compare the sub-periods in terms of probabilities of transition between drought classes, which were used to detect a possible trend in droughts frequency and severity. Results for a number of locations show some similarity between alternate sub-periods and differences between consecutive ones regarding the persistency of severe/extreme and sometimes moderate droughts. In global terms...

SPI-based drought category prediction using loglinear models

Moreira, Elsa E.; Coelho, Carlos A.; Paulo, Ana A.; Pereira, L.S.; Mexia, João T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
37.07%
Loglinear modeling for three-dimensional contingency tables was used with data from 14 rainfall stations located in Alentejo and Algarve region, southern of Portugal, for short term prediction of drought severity classes. Loglinear models were fitted to drought class transitions derived from Standardized Precipitation Index (SPI) time series computed in a 12-month time scale. Quasi-association loglinear models proved to be the most adequate in fitting all the 14 data series. Odds and respective confidence intervals were calculated in order to understand the drought evolution and to estimate the drought class transition probabilities. The validation of the predictions was performed for the 2004–2006 drought, particularly for periods when the drought was initiating and establishing, and when it was dissipating. Despite the contingency tables of drought class transitions present a strong diagonal tendency, results of three-dimensional loglinear modeling present good results when comparing predicted and observed drought classes with 1 and 2 months lead for those 14 sites. Only for a few cases predictions did not fully match the observed drought severity, mainly for 2-month lead and when the SPI values are near the limit of the severity class. It could be concluded that loglinear prediction of drought class transitions is a useful tool for short term drought warning

Spatial and temporal analysis of recent drought using vegetation temperature condition index: case of Somali regional state of Ethiopia

Mekuria, Elias Fekade
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em 01/03/2012 ENG
Relevância na Pesquisa
37.09%
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.; The semiarid and arid areas of the eastern part of Ethiopia have suffered a series of droughts and famines in the years 1999/2000, 2003/2004, 2007 and 2011. Absence/decline of rainfall in two of the rainy seasons locally called Dihra and Gu as being the major fact behind drought. Besides, lack of appropriate monitoring techniques aggravate the situation of drought in the study area. In a region where the numbers of meteorological stations are not sufficient enough to monitor the onset and extent of drought, remotely sensed data presents fast and economical way of information as the ground condition reflects the overall condition of rainfall and soil moisture. In this study, the drought monitoring approach is developed using Terra-MODIS Normalized Difference Vegetation index (NDVI) and Land surface Temperature (LST) level-3 products. The approach integrates the land surface reflectance and thermal properties as well as the NDVI changes to identify the extent and pattern of the past drought years. From the NDVI versus LST scatter plot, we extract Vegetation Temperature condition index (VTCI) to map the variability and trend of the drought years. The year 2003 was found to be the driest year (more than 90% of the region affected by drought) and the season that showed increasing intensity of drought being Dihra. The correlation (r > 0.7) between rainfall and VTCI across the major meteorological stations suggested that the index could be used as good indicator of drought as rainfall does. The overall trend of drought condition for selected drought years suggested that eastern and southern regions will experience more severe drought in the coming year. Moreover...

Drought and low N status limiting maize production in Brazil.

SANTOS, M.X.; LOPES, M.A.; COELHO, A.M.; GUIMARAES, P.E.O.; PARENTONI, S.N.; GAMA, E.E.G.; FRANCA, G.E.
Fonte: In: SYMPOSIUM OF DEVELOPPING DROUGHT AND LOW N-TOLERANCE MAIZE, 1996, El Batan, Mexico. Proceedings... El Batan: CIMMYT, 1997. p. 20-23. . Publicador: In: SYMPOSIUM OF DEVELOPPING DROUGHT AND LOW N-TOLERANCE MAIZE, 1996, El Batan, Mexico. Proceedings... El Batan: CIMMYT, 1997. p. 20-23. .
Tipo: Artigo em anais de congresso (ALICE)
EN
Relevância na Pesquisa
46.82%
The Brazilian territory has an area of approximately 8,5 million km2, which is divided into five main regions with particular characteristics related to average climitaic conditions and natural soil fertility. Climatic variations may be very accentuated within each particular region, but a common feature is the irregular distribution of rains, which causes droughts of variable intensities. Maize is an important crop in most Brazilian regions, occupying approximately 13 million ha and producing annually 28-30 million tons of grain. It has been estimated that drought problems, depending on year intensity, reduce maize production by 14% to 28%. Another limiting factor for maize production in Brazil is the low natural fertility of the soils, especially in nutrients like phosphorus and nitrogen (N). It has been estimated that 80% of the soils in Brazil are deficient in N. Although fertilization is a common solution to this problem, its high costs make this option inaccessible to many farmers. The amount of supplemental N applied to maize in Brazil is low (36 kg N/ha), and of this only 50% to 60% is utilized by the crop. Considering that low N availability and drought are severe constraints to maize crop in Brazil, the National Maize and Sorghum Research Center (CNPMS/EMBRAPA) has initiated breeding programs aimed at the development of germplasm that performs more efficienctly under these two limiting conditions. Several genotypes have been developed on the basis of anthesis-silking interval selection (...); 1997

Overcoming Drought : Adaptation Strategies for Andhra Pradesh, India

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
37.07%
Using recent advances in modeling climate-related risks and adjusting state of the art catastrophic risk modeling techniques to drought, the study conducts an innovative long-term assessment of drought risks in Andhra Pradesh, India, and suggests strategies to reduce their impact, under several economic, drought management and climate change scenarios. The analysis deepens an understanding of climate risk adaptation strategies, including implications for agricultural and catastrophic risk insurance.

Drought : Management and Mitigation Assessment for Central Asia and the Caucasus

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
37.1%
The objective of this study is to raise awareness and understanding of exposure and vulnerability to drought in Central Asian countries and the Caucasus and to introduce a strategic, pro-active framework of mitigation and prevention. The audiences of the report are the governments of Armenia, Azerbaijan and Georgia in the Caucasus and Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan and the Kyrgyz Republic in Central Asia. The report will further be of interest to NGOs and civil society, as well as donors. More specifically, the report should help the ministries of, agriculture, irrigation and water resource management, environment, meteorological services, emergency services, and regional and local government (including municipalities) to improve their preparedness for future droughts. The report explores the ways that effective management and mitigation can soften the impact of drought in Central Asia and the Caucasus and reduce damage and relief and recovery costs. The inquiry begins with an examination of types of drought and exposure to them. Chapter 2 contains an analysis of vulnerabilities to drought, as well as the capacity of the disaster management structure to mitigate and respond to slow-onset natural disasters of this nature. The ensuing chapter covers different types of drought in 2000-01 (meteorological...

Investing in Drought Preparedness

Wilhite, Donald; Darghouth, Salah; Dinar, Ariel
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
37.09%
Drought is a normal part of climate for virtually every country. This paper notes that in response, a risk-based management approach is more cost effective because it emphasizes improved monitoring and early warning systems; development of strong decision-support systems; identification and implementation of mitigation actions; education and training of policy makers, natural resources managers, and the public; and drought mitigation plans that reduce the most serious impacts. The paper concludes with general recommendations that would benefit all sectors: improving the reliability of seasonal climate forecasts and increasing their use could improve decision making for water management; establishing an automated weather station network could provide end users with near-real time data to improve decision-making; altering operating procedures for water reservoir management and augmenting water storage capacity of surface and subsurface systems could improve drought coping capacity; improving information delivery systems and providing technical assistance could improve decision making by government officials...

Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO₂] and temperature

Gauthier, Paul P. G.; Crous, Kristine Y.; Ayub, Gohar; Duan, Honglang; Weerasinghe, Lasantha K.; Ellsworth, David S.; Tjoelker, Mark G.; Evans, John R.; Tissue, David T.; Atkin, Owen K.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.06%
Climate change is resulting in increasing atmospheric [CO₂], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO₂], sustained warming, and drought on leaf dark respiration (R(dark)), and the short-term T response of R(dark) were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO₂], T, and drought treatments. Using high resolution T-response curves of R(dark) measured over the 15-65 °C range, it was found that elevated [CO₂], elevated growth T, and drought had little effect on rates of R(dark) measured at T <35 °C and that there was no interactive effect of [CO₂], growth T, and drought on T response of R(dark). However, drought increased R(dark) at high leaf T typical of heatwave events (35-45 °C), and increased the measuring T at which maximal rates of R(dark) occurred (Tmax) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO₂]. Elevated [CO₂] increased the Q₁₀ of R(dark) (i.e. proportional rise in R(dark) per 10 °C) over the 15-35 °C range...

Physiological attributes of drought-adaptation and associated molecular markers in the seri/babax hexaploid wheat (Triticum aestivum, L.) population.

Olivares-Villegas, Juan Jose
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2007
Relevância na Pesquisa
37.08%
Agronomic and physiological traits associated with drought adaptation were assessed within the Seri/Babax recombinant inbred line population, derived from parents similar in height and maturity but divergent in their sensitivity to drought. Field trials under different water regimes were conducted over three years in Mexico and under rainfed conditions in Australia. Under drought, canopy temperature (CT) was the single-most drought-adaptive trait contributing to a higher performance (R2= 0.71, p<0.0001), highly heritable (h2= 0.65, p<0.0001) and consistently associated with yield phenotypically (r= -0.75, p<0.0001) and genetically [R(g)= -0.95, p<0.0001]. CT epitomises a mechanism of dehydration avoidance expressed throughout the growing season and across latitudes, which can be utilised as a selection criteria to identify high-yielding wheat genotypes or as an important predictor of yield performance under drought. Early response under drought, suggested by a high association of CT with estimates of biomass at booting (r= -0.44, p<0.0001), leaf chlorophyll (r= -0.22,p<0.0001) and plant height (r= -0.64, p<0.0001), contrast with the small relationships with anthesis and maturity (averaged, r= -0.10, p<0.0001), and with osmotic potential (r= -0.20...

Drought-adaptive attributes in the Seri/Babax hexaploid wheat population

Olivares Villegas, J.; Reynolds, M.; McDonald, G.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.04%
Agronomic and physiological traits associated with drought adaptation were assessed within the Seri/Babax recombinant inbred line population, which was derived from parents similar in height and maturity but divergent in their sensitivity to drought. Field trials under different water regimes were conducted over 3 years in Mexico and under rainfed conditions in Australia. Under drought, canopy temperature (CT) was the single-most drought-adaptive trait contributing to a higher performance (r2 = 0.74, P < 0.0001), highly heritable (h2 = 0.65, P < 0.0001) and consistently associated with yield phenotypically (r = –0.75, P < 0.0001) and genetically [R (g) = -0.95, P < 0.0001]. CT epitomises a mechanism of dehydration avoidance expressed throughout the cycle and across latitudes, which can be utilised as a selection criteria to identify high-yielding wheat genotypes or as an important predictor of yield performance under drought. Early response under drought, suggested by a high association of CT with estimates of biomass at booting (r = -0.44, P < 0.0001), leaf chlorophyll (r = -0.22 P < 0.0001) and plant height (r = -0.64, P < 0.0001), contrast with the small relationships with anthesis and maturity (averaged, r = -0.10, P < 0.0001)...

Evaluation of physiological traits and identification of QTLs for drought tolerance in hexaploid wheat (Triticum aestivum L.).

Izanloo, Ali
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
37.13%
This study comprised three major parts: a comparative physiological study of drought responses under controlled conditions; a genetic study to construct the skeleton map of a doubled haploid (DH) population; and a quantitative trait loci (QTL) analysis to identify QTLs associated with drought tolerance traits in the field. In the first part (Chapter 3), three cultivars of wheat (Triticum aestivum L.) adapted to South Australian conditions were tested for drought tolerance under cyclic drought in growth rooms and glasshouse. Extensive physiological traits, including stomatal conductance, chlorophyll content and fluorescence, ABA content, water status traits (e.g. osmotic adjustment, RWC and leaf water potential), water soluble carbohydrates (WSC) and carbon isotope discrimination (Δ¹ ³C) were measured during experiments. Through these experiments, the drought responses of the three cultivars were physiologically dissected and the likely processes contributing most to drought tolerance were identified. In the South Australian wheatbelt, cyclic drought is a frequent event, represented by intermittent periods of rainfall which can occur around anthesis and post-anthesis in wheat. Three South Australian bread wheat cultivars, Excalibur...

High-throughput shoot imaging to study drought responses

Berger, B.; Parent, B.; Tester, M.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
37.04%
Drought is a complex stress which elicits a wide variety of plant responses. As such, genetic studies of drought are particularly difficult. Elucidation of the genetic basis of components contributing to drought tolerance is likely to be more tractable than that of overall drought tolerance. Certain of the traits which contribute to drought tolerance in plants and the high-throughput phenotyping techniques available to measure those traits are described in this paper. On the basis of the dynamic nature of drought, plant development, and the resulting stress response, the focus is on non-destructive imaging techniques which allow a temporal resolution and monitoring of the same plants throughout the experiment. Information on the physiological changes in response to drought over time is vital in order to identify and characterize different drought-tolerance mechanisms. High-throughput imaging provides a valuable new tool which allows the dissection of plant responses to drought into a series of component traits.; http://jxb.oxfordjournals.org/content/61/13/3519.short; Bettina Berger, Boris Parent and Mark Tester

Drought yield index to select high yielding rice lines under different drought stress severities

Raman, A.; Verulkar, S.B.; Mandal, N.P.; Variar, M.; Shukla, V.D.; Dwivedi, J.L.; Singh, B.N.; Singh, O.N.; Swain, P.; Mall, A.K.; Robin, S.; Chandrababu, R.; Jain, A.; Ram, T.; Hittalmani, S.; Haefele, S.; Piepho, H.P.; Kumar, A.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
37.12%
BACKGROUND Drought is the most severe abiotic stress reducing rice yield in rainfed drought prone ecosystems. Variation in intensity and severity of drought from season to season and place to place requires cultivation of rice varieties with different level of drought tolerance in different areas. Multi environment evaluation of breeding lines helps breeder to identify appropriate genotypes for areas prone to similar level of drought stress. From a set of 129 advanced rice (Oryza sativa L.) breeding lines evaluated under rainfed drought-prone situations at three locations in eastern India from 2005 to 2007, a subset of 39 genotypes that were tested for two or more years was selected to develop a drought yield index (DYI) and mean yield index (MYI) based on yield under irrigated, moderate and severe reproductive-stage drought stress to help breeders select appropriate genotypes for different environments. RESULTS ARB 8 and IR55419-04 recorded the highest drought yield index (DYI) and are identified as the best drought-tolerant lines. The proposed DYI provides a more effective assessment as it is calculated after accounting for a significant genotype x stress-level interaction across environments. For rainfed areas with variable frequency of drought occurrence...

Drought predictions: applications in Australia.

Wong, Geraldine H.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
37.1%
Drought is a global and recurrent natural phenomenon, the inevitable consequence of meteorological variability. This natural hazard brings about devastating effects because water is one of the most fundamental commodities for human survival, and a lack of water can result in varying consequences, from mere inconvenience to life threatening instances. Drought cannot be prevented but its effects can be mitigated through the design of appropriate water resource infrastructure and management strategies. The goal of this thesis is to model the spatial and temporal characteristics of drought occurrence in Australia, the driest continent. In doing so predictions can be made, levels of risk can be evaluated and conditional estimates of drought can be based on climatic state variables. For insight into the nature of drought in Australia, multivariate models of drought characteristics are developed. Preliminary analysis demonstrates high correlations between several drought characteristics, these are the drought severity, intensity and duration. This thesis applies the copula concept, which is a versatile means of modelling their dependence structure. Copulas are multivariate uniform distributions, which allow the joint behaviour of variables to be modelled independently from their marginal distributions. This research extends the application of copulas by investigating the effect of climate variability on copula models and subsequent drought characteristics. Two different copula families are fitted to the drought characteristics to demonstrate the importance of tail dependence when modelling extreme climatic events. An important application of these models is the calculation of return periods of extreme drought events exceeding certain thresholds...

Towards Improved Drought Support for New Entrants into Farming: An Investigation into the Level of Support Offered to New Entrants by Past, Present and Potential Drought Support Measures.

Davies, Jessie
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Relatório
Relevância na Pesquisa
37.14%
Australia is the driest inhabited continent on earth and also experiences a high degree of climate variability. As such, drought, along with many other other climatic extremes, is a recurring feature of the Australian agricultural operating environment. A number of characteristics have been identified that reduce an individual's capacity to manage the financial risk that drought poses. These include: low levels of experience, low levels of stored capital, high debt and low equity. Typically, new entrants into farming possess a number of these characteristics, with significant negative implications for drought resilience. As such, new entrants into farming require both additional and differential forms of drought support, compared to established farmers. In 1992, the National Drought Policy (NDP) was established to provide federally coordinated assistance to drought affected farmers. Since then it has undergone a number of national reviews. In response to the 2008 review of the NDP, the Federal Government and Western Australian State Government jointly implemented a Pilot of Drought Reform Measures in part of Western Australia (WA Pilot), which commenced in july 2010. The pilot tested a range of measures that were designed to better support farmers to prepare for future challenges. This report investigated the suite of drought assistance measures offered within the NDP and the WA Drought Reform Pilot (referred to here as the WA Pilot)...

Overcoming Drought in India : Adaptation Strategies for the State of Andhra Pradesh

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Brief; Publications & Research
ENGLISH
Relevância na Pesquisa
37.12%
The study objectives were designed to enhance the state's capacity to assess long-term effects of drought and increase resilience to drought risks at state, district, and community levels. The process for development of study objectives featured extensive consultation with affected sectors, and with state and national programs that aim to address the effects of drought. The study aimed to: (i) develop a framework for simulating long-term impacts of drought in drought-prone areas and at state levels; (ii) conduct risk assessments of the impacts under different scenarios; and (iii) assist the Government of Andhra Pradesh (GoAP) in development of a strategy for adapting to frequent drought and water deficits. During the study, a model was developed as a powerful tool for thorough drought risk assessments and for investigation of risk coping strategies and climate scenarios on crop yield and production. The model was calibrated using local farming practices and crop selection (that is, rice, maize, jowar (sorghum)...

Effective Drought Management For Sustained Livelihoods in the Middle East

Bogan, Natalie
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 25/04/2014 EN
Relevância na Pesquisa
37.11%
Drought has become a more frequent and a major threat to human security in most of the Arab countries located in arid and semi-arid areas of North Africa and Western Asia. The responses to severe drought in the region’s countries are mainly ex-post (reactive) and tend to emphasize emergency relief, take effect after or during drought events and do not incorporate methods that support water conflict prevention. The United Nations recognizes the need to address water scarcity and drought in the Middle East so they began a new initiative to strengthen national capacities to manage drought and water scarcity this region. This project is an extension of the United Nations initiative and focuses on pre-impact and preparedness drought management planning in the Middle East. 10 pilot countries from the Middle East are involved in the project to provide critical information about the current drought management practices in their individual countries. The project is broken up into two separate sections: Section 1 is the analysis, mapping and identification of critical gaps in pre-impact and preparedness drought management in the Middle East, and Section 2 is a case study of drought management in Israel. For Section 1, responses from the pilot country representatives and a thorough literature review of successful drought management strategies in other arid regions of the world were used to determine opportunities for capacity building and pre-impact preparedness drought management strategies that could be used in the Middle East. Based on the literature review and interview responses from the pilot countries...

The effect of drought on plant water use efficiency of nine NAD-ME and nine NADP-ME Australian C4 grasses

Geijer, Paulina; von Caemmerer, Susanne; Conroy, Jann P
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.06%
We investigated the response to drought of nine NAD-malic enzyme (NAD-ME) and nine NADP-malic enzyme (NADP-ME) C4 grasses. Species were grown from seeds in potted soil in a glasshouse. Seedlings were either watered regularly or exposed to two successive drying cycles of 8-10 d each, after which plants were harvested. Under well-watered conditions, average water use efficiency (WUE; dry mass gain per unit water transpired) was similar for NAD-ME and NADP-ME C4 grasses, and ranged between 6.0 and 8.7 g dry mass kg-1 H2O. Drought enhanced WUE of most species, but to a significantly greater extent in NAD-ME (1.20-fold) than NADP-ME (1.11-fold) grasses. Inhibition of dry matter accumulation (average of 12%) and shoot elongation under drought was similar among the C4 grasses. Leaf dry matter carbon (δ13C) and oxygen (δ18O) isotope compositions were significantly different between the two C4 subtypes. Leaf δ13C averaged -13.3 and -12.2‰, and leaf δ18O averaged 26.0 and 26.9‰ in well-watered NAD-ME and NADP-ME grasses, respectively. Drought significantly reduced leaf δ13C in most C4 grasses by an average 0.5‰. Leaf δ18O was not significantly affected by drought, indicating that leaf δ18O does not reflect drought-induced changes in leaf transpiration of C4 grasses. In the experiment reported here...