Study on Grain Yield Stability and Adaptability of Winter Wheat Genotypes Using Different Stability Indices Under Terminal Drought Stress Conditions

Development of new cultivars with high grain yield (GY) stability and good adaptability under both terminal drought stress (TDS) and normal irrigation conditions, which plays important role in production of wheat, is one of the major goals of wheat breeding program for cold dry areas of Iran. The objective of this investigation was to study the stability and adaptability of GY and genotype × location interaction of some new winter wheat lines under both normal and limited water conditions. Field experiments (EWYT-D) were conducted with 18 new winter bread wheat lines including two checks (CVs Toos and Shahi Cross) using randomized complete block design with three replications under both normal irrigation and TDS conditions. Experiments were carried out in four experimental stations (Ardebil, Hamedan, Miandoab and Mashhad) under limited water conditions, while trials in two stations (Karaj and Ardebil) were conducted under both normal irrigation and TDS conditions during 2005-06 and 2006-07 cropping seasons. Under TDS conditions, trials were irrigated by just the booting stage. Different GY stability parametric methods such as variance of genotype across environment (S2xi),coefficient of variability(CVi%),Wricke's ecovalance(Wi), Shukla stability variance (σ i2), Eberhart and Russell parameters (S2di, bi), Pinethus coefficient of determination (R2), simultaneous selection for yield and stability (ysi), and non-parametric method of rank were used to calculate and determine the GY stability. Combined analysis of variance was done over locations and years. Analysis of variance for GY showed that differences due to genotypes was significantly different (P<0.01) under both normal irrigation and TDS conditions. The location × year and genotype × location inreractions were highly significant (P<0.01). The genotype × location × year interaction was highly significant (P<0.01). The genotype × location × year interaction was highly significant (P<0.01) just in TDS conditions, while it was not significant under normal irrigation conditions. From these results, it is concluded that four new promising wheat genotypes incuding lines No. 2 (Mv17/Zrn) and No. 9 (Bkt/90-Zhong 87) were the most stable lines with high GY and good adaptability and agronomic characters under TDS conditions.