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Current wheat improvement programs focuses on development of new high yielding, disease resistant, stable and climatic resilient genotypes. Late planting is one of the major abiotic stresses, seriously influencing wheat production. In the current study, twenty seven bread wheat genotypes along with one check cultivar (Pirsabak-2008) were evaluated independently under normal (optimal) and late (stress) planting conditions at Cereal Crops Research Institute (CCRI), Pirsabak Nowshera Khyber Pakhtunkhwa Pakistan during 2013-14. Analysis of variance revealed highly significant (P < 0.01) differences among the genotypes, sowing dates and genotype × sowing dates interactions effects for the studied traits. Generally, reduction in plant height (0.41 to 10.91%) and grain yield (0.36 to 53.35%) was observed among the tested genotypes under late planting as compared to normal (optimal) planting. Least % reduction in grain yield was recorded for genotypes BWL-23 (0.36%), BWL-4(0.76%) and BWL-16 (1.22%) as compared to check (Pirsabak-2008). Eight stress selection indices i.e. Mean Productivity (MP), Tolerance (TOL), Geometric Mean Productivity (GMP), Harmonic mean (HM), Stress Selection Indices (SSI), Stress Tolerance Index (STI), Yield Index (YI) and Yield Stability Index (YSI) were determined for each genotype. Correlation analysis revealed that plant height and grain yield under both the planting conditions, had significant positive correlation with stress selection indices i.e. GM, HM, SSI and YI. These selection indices could be effective in identification of genotypes to late planting. Based on MP, GMP, HM, STI and YI genotypes i.e. Pirsabak-2008, BWL-23 and BWL-27 were found late planting stress tolerant and could be sown in both normal and late planting conditions.
Keywords: Abiotic stress; Genetic potential; Grain yield; Normal and late planting; Stress selection Indices; Tolerance; Variabilit