Combination of traits at two developmental stages under salt stress as a measure of tolerance in a reciprocally crossed rice (Oryza sativa) population

Abstract

The rice (Oryza sativa L.) landrace Horkuch from Bangladesh maintains efficient photosynthesis and detoxification under salt stress and was therefore considered to be a useful donor for tolerance traits. Reciprocally crossed bi-parental mapping populations were generated from salt-tolerant Horkuch and high-yielding salt-sensitive variety IR29, in order to identify superior salt-tolerant high-yielding lines as donors. The present study reports on the phenotypic screening data of ~300 F3 segregating populations from the reciprocal cross and their parental lines in seedlings and screening of a subset at maturity stage under gradual salt stress of 12 dS m–1 for seedlings and 8 dS m–1 for mature plants. Correlation, broad-sense heritability and principal component analyses for salt tolerance as well as yield-related traits were conducted in the populations at the two developmental stages. Level of salt injury was found to be correlated with traits such as filled grain weight at maturity stage and biomass-related traits at the seedling stage. This association between yield-related and survival traits helped to identify tolerant and sensitive plants, which were predicative of agronomic performance under salt stress. Moreover, use of the reciprocal-cross population showed how cytoplasmic inheritance of specific traits such as K+ concentrations can affect characteristics of donor plants. Measurement of a large number of traits and analysis of their co-inherited interrelation can therefore help identify the best performing plants under salt stress for effective breeding strategies. The data are being utilised in mapping of quantitative trait loci, and selected progenies are being used as breeding lines for producing durable salt-tolerant, high-yielding rice varieties.