Morpho-physiological characterization and selection of heat tolerant wheat lines using selection indices

Heat stress is one of the major constraints in wheat production due to its adverse effect on grain yield and component traits. Moreover, it negatively affects the physiological, biochemical and quality traits of wheat. Therefore, selection of heat tolerant wheat lines is one of the major breeding goals for wheat scientist. In present study, 238 recombinant inbred lines were evaluated along with their parents WH 711 × WH 542 under timely and late sown (heat stress) condition. The heat tolerance indices were calculated based on grain yield under normal and stress conditions. The mean grain yield of 238 wheat lines was reduced by 20.54% suggesting critical effect of heat stress on grain yield. The harmonic mean (HM), stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), and mean relative performance (MRP) were correlated significantly and positively with grain yield under stress and normal conditions. Whereas, Tolerance index (TOL) was correlated negatively with grain yield under stress conditions and positively under normal condition. Based on STI, MP, HM, GMP and MRP, wheat lines WL 92, WL 119, WL 114, WL 110, WL 6 were identified as heat tolerant and could be utilized as potential lines for increasing heat stress tolerance of future wheat breeding programs.