General and specific combining ability estimates of physiological traits for moisture stress tolerance in groundnut (arachis hypogaea l.).

ABSTRACT

The combining abilities for physiological traits in peanut were examined to understand the type of gene action governing these traits, and to identify peanut genotypes suitable for use as parents in breeding for improvement in physiological traits. Substantial genetic variability was observed among the hybrids for the traits studied. The genotypes, TPT-4 and ICGV-91114 were found to be good combiners for developing early flowering types, while ICGV-91114, TCGS- 584, TPT-4 and JL-220 were good combiners for developing early maturing. For SPAD chlorophyll meter reading was K-1375 was best general combiner. Among the parents K-1375, TIR-25 and TCGS-647 were found to be superior as evident from its highest significant positive general combining ability effects for specific leaf area. The best good combiner for transpiration rate was ICGV-91114 and for photosynthetic rate was TIR-25. For water use efficiency only the genotype, TPT-4 was the best combiner. Best performing parents for harvest index were JL-220 and TPT-4. The hybrid, TPT-4 x TIR-25 was the specific hybrid for high water use efficiency. For SPAD chlorophyll meter reading only one cross, K-1375 x TCGS647 was considered to be the good performing hybrid. Two hybrids viz., TIR-25 x TCGS- 647 and ICGV-91114 x JL-220 were found to be good specific combiners for harvest index. A perusal of results of combining ability analysis indicated considerable non-additive gene action in the inheritance of majority of the attributes studied. The non-fixable dominance deviation and epistatic effects are likely to hinder improvement through simple pedigree selection, which is commonly followed in groundnut. Alternatively intermating of the F2 segregants followed by recurrent selection and pedigree breeding can harness the different kinds of gene - effects. Repeated selection and inter-mating of segregating materials for two or three cycles, makes it possible to achieve simultaneously improvement in physiological attributes.