Relationships and repeatability of drought tolerance indices in wheat-rye disomic addition lines

Abstract

This study was conducted to (i) investigate the relationships and repeatability among several drought tolerance/resistance indices obtained from the grain yield data of a set of wheat-rye [Chinese spring-Imperial (CS-IMP)] disomic addition lines (DALs) grown under rainfed and irrigated conditions for three years; and (ii) locate the genes controlling drought tolerance/resistance in rye (Secale cereale). The results of combined analysis of variance showed that the environment, genotype and GE interaction effects were highly significant (P< 0.01). Differences in ranking of genotypes based on each index from year to year, exhibited that drought tolerance of genotypes are influenced by year effect. Principal component analysis (PCA) based on the Spearman's rank correlation matrix revealed that drought tolerance/resistance indices were significantly inter-correlated with each other indicating that several of the indices probably measure similar aspects of drought tolerance/resitance. The stress tolerance index (STI), geometric mean productivity (GMP), harmonic mean (HM) and mean productivity (MP) were consistently correlated with each other over the years, indicating that they can be used as alternative for each other to select drought tolerant genotypes with high yield performance in both stress and non-stress conditions. The stress susceptibility index (SSI), yield stability index (YSI), tolerance (TOL) and sensivity drought index (SDI) showed repeatable correlations over the years and can be used to screen the drought resistant and stable genotypes. According to multiple year data, most of the genes controlling drought tolerance in rye are located on chromosome 7R, 5R and 3R, while the genes controlling drought resistance are located on chromosomes 2R, 4R and 6R.