Response of Four Spring Wheat Cultivars to Drought Stress

Abstract

Identification and understanding of the mechanism of drought tolerance in wheat (Triticum aestivum L.) cultivars has long been a major goal of plant breeders. Our objective was to determine if leaf water potential, osmotic potential, yield, and yield components could be used to differentiate apparent drought tolerance among the cultivars. Four spring wheat cultivars (Giza 165, Gemmiza I, Klassic, and SPHE3) from different geographic regions were grown in a greenhouse at 20/ 15°C with 12 h of daylight augmented with artificial lighting and subjected to water stress imposed by withholding irrigation at different stages of growth. The three treatments were: no stress (WI); I0 stress at tillering OV2); and I0 d stress at heading OV3). Water stress caused large differences for yield and yield components. For the W3 treatment, Giza 165, Gemmiza I, and SPHE3 had yield decreases of 44%, 43%, and 18%, respectively, while Klassic had a yield increase of 4%. The average slopes of the turgor vs leaf water potential plots were 0.56 for Giza 165 and Gemmiza I vs 0.43 for Klassic and SPHE3 at heading. The difference between the two groups was statistically significant as determined by the 95% Tukey test. Stress applied at either tillering or heading gave similar results but effects were more pronounced when stress was applied at heading. It was not possible to determine if osmotic adjustment contributed to the differences between cultivars in response to water stress.

Main Stem and Tiller Contribution to Wheat Cultivars Yield Under Different Irrigation Regimes

“…Souza and Soares Sobrinho (1983) also reported that the BH-1146 cultivar adapted better to water stress. Moustafa et al (1996) and Villareal et al (1998) showed that certain cultivars react better under water stress. The Cocoraque cultivar highest tiller/total yield ratio was 11.6%.…”

“…They found that irrigation could increase yield up to 4.7 times in years with low rainfall during the plant growth period. Reduction in grain yield also depends on the genotype cultivated and the physiological stage of the plants under stress (Hobbs, 1953 ;Robins and Domingo, 1962;Singh et al, 1979;Sairam et al, 1990;Blum et al, 1990;Thompson e Chase, 1992;Moustafa, et al, 1996;Ravichandran e Mungse, 1997;Villareal et al, 1998;Guerra e Antonini, 1996). Souza and Soares Sobrinho (1983) found that the BH-1146 cultivar had more stable yield under the most adverse environmental conditions due to its tolerance to toxic acid soils, drought, temperature variations and different sunlight conditions.…”

Plant traits to complement selection based on yield components in wheat

“…A major limitation has been the lack of a technique to identify drought tolerance that is repeatable and that can be used in populations where genetic segregation is present. The multitude of factors involved in plant response to water stress makes it difficult to provide a test of drought tolerance (MOUSTAFA et al, 1996).…”

Variation induction in wheat via gamma-rays and hybridization and gains from selection in derived heterogeneous populations for drought tolerance

“…Several workers reported also wheat genotypic differences under both drought stress and non-stress conditions in number of spikes/plant (Mosaad et al 1995, Moustafa et al 1996, and Al-Naggar et al 2004 and plant height ( Sharma and Bhargava 1996, Khanna et al 1986and Al-Naggar et al 2004.…”

“…To start a proper wheat breeding program for improving drought tolerance, the source populations should possess sufficient genetic variability amenable for selection. Unfortunately, with present distribution of improved high yielding, pure line cultivars in all of the world's wheat growing areas, selection from established cultivars would rarely isolate a new genotype (Poehlman and Sleper, 1995). Two breeding procedures, i.e., mutation and hybridization are used to induce new genetic variation.…”