Effect of Water Stress on Physiological Attributes and their Relationship with Growth and Yield of Wheat Cultivars at Different Stages

Abstract

The eects of water stress on physiological attributes of drought-sensitive (Kalyansona) and drought-tolerant (C-306) wheat cultivars were studied in a pot experiment. Water stress was imposed by withholding irrigation at boot and anthesis stages. Leaf water potential, leaf osmotic potential and leaf turgor potential (measured with 1 1 pressure chamber and osmometer), as well as leaf diusive resistance, leaf transpiration rate and leaf-to-air transpiration gradient (measured with a steady-state porometer) were measured diurnally. Growth and yield parameters were recorded after harvesting of the crop. Triplicate data were analysed using a completely randomized design and correlations amongst these parameters were computed. Water stress was found to reduce diurnal leaf water potential and leaf osmotic potential in both the genotypes but leaf osmotic potential was signi®cantly higher in the droughttolerant cultivar C-306 than in the drought-sensitive cultivar Kalyansona. Positive turgor was recorded in both the genotypes under water stress and non-stress conditions. Water-stressed plants showed signi®cantly lower turgor potential than control plants. In diurnal observations, water-stressed plants exhibited signi®cantly higher leaf diusive resistance in both genotypes at both stages. The diusive resistance of C-306 was predominantly higher than that of Kalyansona. Water stress decreased leaf transpiration rate at both stages but the reduction was higher at the anthesis stage. The leaf-to-air temperature gradient was much higher in C-306 than in Kalyansona at the boot stage but at the anthesis stage genotypic variation was non-signi®cant. The capacity to maintain cooler foliage was lower at the anthesis stage than at the boot stage in both the cultivars. Shoot dry weight, number of grains, test weight 2 2 , grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage, while imposition of water stress at the boot stage caused a greater reduction in plant height and number of tillers. Similarly, water stress caused a smaller reduction in growth, yield and yield attributes in C-306 than in Kalyansona.In general, the correlation coecient of grain and biological yield with water potential and its components was positive and highly signi®cant. Similarly, turgor potential was also correlated positively and signi®cantly with grain yield at both the stages, but with biological yield it was signi®cant only at the anthesis stage. A negative and signi®cant correlation was obtained for diusive resistance and leaf-to-air temperature gradient with grain yield at the boot and anthesis stages. The rate of transpiration was also positively and signi®cantly correlated to grain and biological yields at both the stages. Amongst the yield attributes, number of leaves and number of tillers were positively correlated at the anthesis stage, whereas leaf area and shoot dry weight were signi®cantly correlated with grain and biological yields at both the stages.

Differential agronomic responses of bread wheat cultivars to drought stress in the west of Iran

“…Also Gupta et al (2001) reported that during wheat anthesis period, drought stress reduced stem dry weight, number of grains, 1000 grain weight, grain yield, harvest index and biological yield.…”

“…Debake et al (1996) demonstrated that imposing stress, especially after anthesis stage, entailed a significant decrease in harvest index. Gupta et al (2001) declared that there was a direct positive relation between biological yield and grain yield. Harvest index is so extremely affected by environmental changes that its value increases under desirable climatic conditions and decreases under drought stress condition at final period of plant growth (Siddique and Whan, 1994).…”

The Impact of Drought Stress on some Morpho-Physiological Traits and RAPD Markers in Wheat Genotypes

“…Stress tolerance and susceptibility indices including mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), drought susceptibility index (DSI) and yield stability index (YSI) for water deficit environment were calculated based on grain yield under sever water stress (50% FC) and unstressed (100% FC). Stress tolerance attributes were calculated by the following formulae: Mean productivity (MP) and Tolerance (TOL) was calculated according to Gupta et al (2001 Chaudhuri and Kanemasu (1982) where, Ys = mean yields of a given genotype in WS (50% FC) condition; Yp = mean yields of a given genotype in NS (100% FC) condition; DII = Drought intensity index. The drought intensity index (DII) for each water regime was calculated as DII =1 -Xs/X p Genotyping DNA Genomic DNA was extracted following the phenol-chloroform method of Pallotta et al (2000) with some minor modifications.…”

Water Deficit Stress Tolerance in Some of Barley Genotypes and Landraces under Field Conditions

“…Also, they reported agronomic traits such as grain yield and its components are the major selection criteria for evaluating drought tolerance under field condition. Gupta et al (2001) studied physiological and yield attributes of two wheat genotypes with stress at boot and anthesis. They indicated that number of grains, grain yield, biological yield, and harvest index decreased to a greater extent when water stress was imposed at anthesis stage.…”