气候变化领域集成服务门户

The unpredictability associated with recent climatic changes like rainfall, drought and heat has affected agricultural crop productions severely, worldwide including Pakistan. Various stresses, particularly drought and specifically "terminal drought" is largely affecting chickpea production in its major growing environments of arid and semi-arid tropics. This demands availability of drought-tolerant chickpea genotypes to mitigate such yield losses. For this purpose, separate experiments under normal and drought-stressed conditions were conducted for three consecutive years (2014-17). The plant material comprised sixty genotypes, laid out in an alpha-lattice design. No irrigation was applied to drought-stressed experiments while normal experiments were irrigated twice at critical growth stages. Twelve drought-tolerance relevant parameters were computed from grain yield under normal (Yp) and drought-stressed (Ys) environments. These included mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), tolerance index (TI), drought resistance index (DRI), relative drought index (RDI), stress susceptibility index (SSI), stress tolerance index (STI), modified stress tolerance index for normal (kiSTI), modified stress tolerance index for stressed (k(2)STI), yield index (YI) and yield stability index (YSI). Variance analyses suggested significant differences among all the indices computed. High to moderate genotypic and phenotypic variances alongwith GCV, PCV indicated prevalence of additive gene action for TI, Yp, Ys, HM, GMP, MP, SSI, k(2)STI, DRI and k, STI. Estimates of heritability and genetic advance were high for TI, Yp, Ys, HM, GMP and MP. Positive and significant correlation of Yp with Ys, MP, GMP, HM, TI, SSI, STI, k(1)STI, k(2)STI, YI and Ys with MP, GMP, HM, DRI, RDI, STI, k(1)STI, k(2)STI, YI, YSI suggested that these are the superior predictors of grain yield under normal and stressed conditions, respectively. Principal component analysis dissected PC1 and PC2 with eigenvalues > 1 and explicated 59.5% and 38.1% of the total variability, respectively and assorted stress-tolerant and susceptible genotypes. Based on the results, genotypes K-01006, K-01101, K-01104, K-01105 and K-01111 were declared as most stable under both stress and non-stressed environments.