Document Type : Original Article
Authors
1
Wheat Res. Dept., Field Crops Res. Inst., Agric. Res. Cent. Giza, Egypt
2
Agron. Dept., Fac. Agric., Zagazig Univ., Egypt
Abstract
Water deficit is one of the major stresses that reducing wheat production particularly under current climate change. The aim of this study was to investigate the genotypic variation of thirty bread wheat genotypes under water deficit and normal irrigation conditions. In addition, to clarify the association between grain yield and the other important agronomic traits, and to determine the interrelationships among the tested traits under both conditions. Two field experiments were carried out in New Valley, Agricultural Research Station conditions, Agricultural Research Center, Egypt during 2014-2015 and 2015-2016 growing seasons. Thirty bread wheat genotypes were evaluated under two irrigation regimes. The normal irrigation was used every 15 days (NI) with total nine irrigation times per season (2900 m3/fad.). The other irrigation regime was applied every 30 days giving in total five irrigation times (1900 m3/fad.) providing water deficit conditions (WD). The experimental design was laid out in a spilt-plot in which irrigation treatments were in the main plots and genotypes were randomized in the sub-plots, in three replications. All evaluated traits were affected significantly by irrigation treatments. The genotypes; G1, G2, G17, G21, G22, G23, G24 and G27 exhibited good grain yield/plant and its components under both conditions. Tolerance indices; mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI) and yield index (YI) were calculated based on grain yield/plant under both conditions. The highest indices were observed for G21, G2 and G1 genotypes followed by G23, G27 and G24 genotypes. Based on these indices, the genotypes were classified into three groups A (drought tolerant), B (moderate drought-tolerant) and C (drought-sensitive) with 8, 18 and 4 genotypes, respectively. Furthermore, phenotypic and genotypic correlation coefficients were estimated and it was observed strong and significant positive correlation between grain yield and 100-grain weight, grain weight/spike, biological yield/plant and harvest index under both conditions. Additionally, path analysis was calculated and it was found that biological yield and harvest index exhibited the highest positive direct effect on grain yield under both conditions. On the other hand, the highest indirect effects on grain yield were assigned for number of spikes/plant followed by flag leaf area, grain weight/spike and 100-grain weight under both conditions. Which demonstrates the importance of these traits in improving grain yield under both conditions.
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