Path Analysis of Phenotypic Stability and Drought Tolerance in Bread Wheat (Triticum aestivum L.)

摘要

In order to determine stable and drought-tolerant bread wheat genotypes and relative contribution of yield components in the genotype-environment (GE) interaction, field experiments were conducted with 14 genotypes for 3 consecutive years (2008-2011)under rainfed and irrigated conditions. Descriptive diagrams and combined analysis of variance indicated highly significant differences for GE interaction and high variability for yield and yield components indicating the possibility of selection for stable and drought-tolerant genotypes. AMMI-stability value (ASV) and yield stability index (YSI) discriminated genotype 10 as the most stable genotype with high grain yield (534.5 g). Path analysis revealed that the relative contribution of a genotypic component 1000-seed weight (TSW) in the phenotypic stability of grain yield was higher than that of number of spike per plant (SPP) and number of seed per spike (SPS). Environmental components of GE interaction exhibited that absolute value of r_1 (first environmental component) in all environments was higher than the second (r_2) and third (r_3) environmental components. In addition, variation of r_1 was more than r_2 and r_3, and that of r_2 was higher than r_3 indicating that sensitivity of number of spike per m~2 (NS) and SPS to the environmental variation was higher than TSW. Therefore high grain yield and stability of genotype 10 was because of higher genotypic component V_3 (TSW) and lower environmental components r_3 (TSW). Path coefficient and cluster analysis of drought susceptibility index (DSI) discriminated genotypes Croos alborz, Ww33GVee"S,,.Mrn.3.Atilla.Tjn, Aazar-2, Sardari, Azd.HD2172..Kayson.Glenson.3.170-28.Ning8201, Ww33GVee"S".Mrn.3.Atilla.Tjn and T.AEST..SPRW"S"..CA8055.3.BACANORA88ICW92-0477 as drought tolerant with high grain yield for rainfed condition, while genotypes Shi#4414.Crow"S"..Fow-l and CHAM-8.MAYON"S,.CW93-0031-1AP-OL-OBR-2AP-1AP-OAP as drought sensitive and desirable for irrigated condition.