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Search Results: 1 - 10 of 30367 matches for " water stress "
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Water Stress Estimation from NDVI-Ts Plot and the Wet Environment Evapotranspiration  [PDF]
Daniela Girolimetto, Virginia Venturini
Advances in Remote Sensing (ARS) , 2013, DOI: 10.4236/ars.2013.24031
Abstract:

In this work we present a new simple index to estimate water stress (WS) for different types of surfaces, from remotely sensed data. We derive a WS index, named WSIEw, modifying the Water Deficit Index (WDI) proposed by Moran et al. by using the wet environment evapotranspiration (Ew) instead of the potential evapotranspiration (Epot) concept. Jiang and Islam model was used to simulate actual evapotranspiration (ET) and Priestley and Taylor equation to estimate Ew. The WSIEw results were compared to ground observations of ET, precipitation (PP), soil temperature (Tsoil) and soil moisture (SM) in the Southern Great Plains-EEUU. Preliminary results suggest the method is sensitive to the water status of different surfaces. However, the WSIEw would range from 0 to 0.7, having a value of 0.4 for a dry surface with 5% of SM. The methodology is operationally

Effect of Water Deficit Imposed during the Early Developmental Phase on Photosynthesis of Cocoa (Theobroma cacao L.)  [PDF]
Kayode Olufemi Ayegboyin, Ezekiel Akinkunmi Akinrinde
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.71002
Abstract: A greenhouse study was carried out at Cocoa Research Institute of Nigeria, Ibadan to study the effect of water stress on the four popular cocoa genotypes at the institute. F3 Amazon, T1, T7 and Amelonado were raised under different water regimes (daily, 3-day interval, 5-day interval and 7-day interval) at 100%, 50% and 25% field capacities. Data were collected on the height, leaf area, root length, stomata conductance, photosynthetic rate and water use efficiency of the plants. Results showed that plant performances showed genotypic variation in their response to water stress. Generally, there were linear and positive relationships between water level and values in both physiological and morphological responses of cocoa genotypes.
Water requirements and single and dual crop coefficients of sugarcane grown in a tropical region, Brazil  [PDF]
Vicente de P. R. da Silva, Cícera J. R. Borges, Carlos H. A. Farias, Vijay P. Singh, Walker G. Albuquerque, Bernardo Barbosa da Silva
Agricultural Sciences (AS) , 2012, DOI: 10.4236/as.2012.32032
Abstract: A field experiment was conducted throughout 2009/2010 in a sugarcane field of a commercial distillery located on the coastal area of Paraiba state, Brazil. The objectives were to determine sugarcane water requirements and to test the single and dual crop coefficients by comparing the calculated values of ET with measured ones. Crop evapotranspiration was determined by field water balance, reference evapotranspiration (ETo) by the Penman-Monteith approach, while single and dual crop coefficients were computed through the standard FAO-56 methodology. The experimental area was cultivated with irrigation applied weekly by a centre pivot system in addition to rainfall and the irrigation scheduling was based on 100% ETo. Three statistical tests, mean bias difference (MBD), normalized root mean square difference (NRMSD) and regression analysis, were used to evaluate the performance of single and dual crop coefficients. Results showed that there was a notable symmetry between ET measured and ET calculated by Kc dual. The ET values, calculated from Kc single, underestimated those obtained from soil water balance measurements by 36%.
An Empirical Approach to Get the Vitality of a Genotype to Water Stress Tolerance in Yield and Yield Contributing Traits  [PDF]
Ijaz Rasool Noorka, Saba Tabasum
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.45123
Abstract:

Conventional methods of plant breeding and agronomic practices remained a successful tool to maintain the pace of food production for centuries but due to changing climatic conditions and the challenges of 21st century like population growth, pollution, declining biodiversity and food security have shaken the previous policies. This situation compelled the agriculturist towards the judicious management of natural resources to combat the poverty, disasters and increased food demands. The present study was initiated to check wheat varieties in two water provision conditions. The results revealed that environmental stresses played negative role by minimizing the yield and yield contributing traits. However the severity of water stress was depleted by some promising genotypes by showing minimum hazard effects and by having capability to contribute to conserving biodiversity, ensuring sustainability, combating food insecurity and increasing economic benefits. The minimum effect of moisture stress on grain yield was shown by genotypes C-518 (12.97%) while the genotype Shakar, Pari-73 and Uqab-2000 showed maximum decline percentage. The global warming and population explosion will further induce commodity shortage and law and order situation in the world. The prevailing International tension can be cooled down by the provision of marshal aids by the developed countries to the effected or threatened countries.

Expression Analysis of Two Genes Coding for Trehalose-6-Phosphate Synthase (TPS), in Sugarcane (Saccharum spp.) under Water Stress  [PDF]
Nilson Nicolau Junior, Mariana Sant’Anna Pereira Nicolau, Luana Jandhy Mantovanini, Sonia Marli Zingaretti
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.412A3011
Abstract:

The accumulation of trehalose (α-D-glucopyranosyl-[1,1]-α-D-glucopyranoside), a sugar with osmoprotectant properties, is very common in microorganisms, invertebrates and in resurrection plants. However, in the majority of higher plants, it is found in trace amounts. Trehalose is synthesized from the UDP-glucose and glucose-6-phosphate in a two-step process with two enzymes, trehalose-6-phosphate synthase or TPS (EC 2.4.1.15 and EC 2.4.1.36) and trehalose-6-phosphate phosphatase or TPP (EC 3.1.3.12). The trehalose-6-phosphate synthase and its product of the trehalose-6-phosphate (T6P) are probable signaling molecules in the carbohydrate metabolism, contributing to enhancing the plants tolerance to water stress. Water scarcity is one of the most important factors that influence productivity in sugarcane (Saccharum spp.) and it activates a cascade of metabolic events and necessary morphologic changes for the survival of the plant under stress. Here we show the in silico expression study of TPS in different libraries from the SUCEST project. Our results showed that the TPS genes are present in all tissues and that they are divided into two subfamilies (class I and II). It is shown that STPS1 belongs to the class I, therefore, it does not have an active phosphatase (TPP) domain, whereas, the STPS2 has an active TPP domain (class II) determined by the presence of phosphatase boxes. Expression analyses based on the semi-quantitative method of the reverse transcription polymerase chain reaction (RT-PCR) show that the STPS1 gene is up-regulated in the tolerant cultivar under stress and down-regulated in susceptible plants. The STPS2 gene does not show considerable variations in the expression levels under the same treatments. The discovery of active genes such as STPS1 and STPS2 in plants under water stress, contributes for the concerning about the cascade of responses in plants under water deficit and points out to target genes for plant breeding.

Evaluation and Selection of High Biomass Rice (Oryza sativa L.) for Drought Tolerance  [PDF]
Aditi Kondhia, Rodante Escleto Tabien, Amir Ibrahim
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.612197
Abstract: Biomass production is important in increasing yield not only for food but also for bio-fuel production that depends on high dry matter. Due to climate change, occurrence of drought may be prevalent and this affects both grain and biomass yields in crops including rice. The objectives of this study were to determine the performance of selected high biomass breeding rice lines to different levels of drought and use several drought tolerance indices to identify best genotypes that could be grown in unfavorable water stressed areas. A rainfed and flooded trial was conducted to evaluate 20 selected breeding lines for biomass production and ten entries from the same set were grown in the greenhouse at three different field capacities (FC, 50%, 75%, 100%). Most of the genotypes performed well under non-stressed conditions (flooded and 100% FC) but some genotypes performed well in water stressed condition. The plants had lower plant height, tiller plant-1, and total biomass at maturity under rainfed conditions and their flowering was delayed compared to flooded conditions. In the greenhouse, water stress slowed the rate of increase in height, and produced lower shoot and root weight, percent dry matter (% DM) and total biomass. However, drought enhanced the rate of tiller production. Two genotypes were found to more tolerant to drought stress and could be used for cultivation under water stress condition to get optimum biomass yields. These genotypes can be identified using drought tolerance indices, particularly stress tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP) and harmonic mean (HARM), as these have a similar ability to separate drought sensitive and tolerant genotypes. Genetic and molecular analyses, and detailed characterization of these genotypes will help understand their inheritance pattern and the number of genes controlling the traits and determine specific leaves and root traits important in developing high biomass rice.
Influence of Foliar Applied Nitrogen on Reproductive Growth of Sunflower (Helianthus annuus L.) under Water Stress  [PDF]
Muhammad Haseeb, Nazimah Maqbool
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.612137
Abstract: Nitrogen is a major nutrient involved in plant growth and yield. Plants cannot get the nutrients from the soil medium under water stress condition to testify foliar application in stress condition to fulfil plant need for better performance. In this regard, a field study was conducted to evaluate the effect of foliar-applied nitrogen (0, water and 1% urea) on sunflower (cv. Hysun-33) under normal and water stress at reproductive stage. Two soil applied nitrogen levels control (0 kg·ha-1) and recommended dose (115 kg·ha-1). Supplemental foliar application of nitrogen in the form of urea significantly increased the growth, yield and yield components of sunflower under water stress. The increase in yield with 1% urea spray was recorded up to 1.37 t·ha-1 in comparison to water spray (1.07 t·ha-1) and no spray (1.00 t·ha-1). While maximum values of all factors were obtained where 1% urea spray with soil applied nitrogen was used in both stresses as well as in non-stress condition. Therefore, reasonable yield can be achieved by applying foliar application of urea (1%) as a supplemental source to soil applied nitrogen under water stress.
Effect of water stress at different periods on seed yield and water use efficiency of guar under Shambat conditions  [PDF]
Mahmoud Fadl el Mula Ahmed, Deng Manasseh Mac, Awatif Abdel Gadir Bashir
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.23034
Abstract: Water stress effects on seed yield and water use efficiency of three indeterminate guar (Cyamopsis tetragonoloba L. Taub.) lines (L12, L18 and L33) were investigated in the experimental farm of the Faculty of Agriculture, University of Khartoum for two seasons (2005 and 2006). The guar lines were subjected to water stress induced by withholding irrigation for three weeks. Three water stress treatments were imposed 35, 50 and 65 days after sowing (DAS), and a control treatment irrigated every two weeks. The treatments were arranged in a split-plot design with three replications; with water regime treatments assigned to the main plots and guar lines to the subplots. Data were recorded on seed yield (t.ha–1), number of pods per plant, 1000- seed weight (g), harvest index (HI) and water use efficiency at harvest. The results indicated that exposure of several cultivars of guar to water stress at the three stages of growth didn’t induce any significant effect on number of pods per plant, 1000-seed weight, seed yield and water use efficiency (WUE). On the other hand there was significant reduction in harvest index as a result of imposition of water stress at 35 and 50 DAS. It was also evident that plants re-watered after the stress recovered and had the same values as the control treatment.
Níveis de déficit hídrico em diferentes estádios fenológicos da cultura da berinjela (Solanum melongena L.)
Carvalho, Jacinto de A.;Santana, Márcio J. de;Pereira, Geraldo M.;Pereira, Joelma R. Dur?o;Queiroz, Tadeu M. de;
Engenharia Agrícola , 2004, DOI: 10.1590/S0100-69162004000200010
Abstract: the effects of different levels of water deficit, applied in two fenological phases of eggplant crop, were measured in an experiment conducted in a green house of the department of engineering - ufla, in lavras - mg, brazil. a complete randomized experimental design was used in a factorial array of 2 x 4, being two phenological phases (after-transplanting/opening of the floral bud and fruits formation/harvest) and four levels of water deficit (100; 80; 60, and 40% of the evapotranspiration), in eight treatments with six replications. the stem diameter, height of the plants and number of leaves were evaluated in different times, production and number of fruits. the results showed that the production and the number of fruits were more affected by the water deficit when it occurred during the phase of formation of the fruits, and that, the quality of the fruit was more affected than the total production. the increase of the water deficit resulted in smaller values of the height of the plant, diameter of the stem and number of leaves, independently of the application time.
EFECTOS DE LA RESTRICCIóN DEL RIEGO EN DISTINTOS PERíODOS DE DESARROLLO DE LA VID CV. CABERNET SAUVIGNON SOBRE PRODUCCIóN Y CALIDAD DEL VINO
Ferreyra E.,Raúl; Selles V.,Gabriel; Peralta A.,Jose; Burgos R.,Loreto; Valenzuela B.,Jorge;
Agricultura Técnica , 2002, DOI: 10.4067/S0365-28072002000300006
Abstract: different water stress treatments were applied to cabernet sauvignon vines (vitis vinifera l.) during the 1994/95 and 1995/96 seasons at la platina research center, santiago (33o34? s. lat; 70o38? w. long). treatments t1 and t2 were 100% and 40% of the crop evapotranspiration (etc) during the whole season; t3 had no irrigation from budburst to veraison followed by 100% etc until harvest; and t4 100% etc from budburst to veraison and no irrigation until harvest. stressed treatments (t2, t3 and t4) significantly reduced weight and size of berries. yield was also reduced, mainly when no water was applied between budburst and veraison (t3). in addition, in the following season, floral induction was affected by water stress. wine color intensity, phenols and anthocyanin concentration were higher in the stressed treatments, while acidity was increased when water stress was applied between veraison and harvest. the attributes and global quality of the wine were favored by water stress, especially after veraison. the stem water potential (swp) and plant water stress index (pwsi) were adequate indicators of plant water status
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