Identification of Indices for Empirical Selection of Dolichos Bean [Lablab purpureus (L.) Var. Lignosus] Genotypes for Tolerance to Terminal Moisture Stress

Abstract

Background: Detection and quantification of variability among germplasm accessions/segregating populations/advance breeding lines is a pre-requisite (among others) for breeding crop plants for drought tolerance. Indices that integrate yield under moisture stress free (MSF) and moisture stress (MS) have been developed and used for screening and selection of moisture stress tolerant genotypes in several crops. The present study was aimed at identifying desirable indices from among those reported for screening and selection of terminal moisture stress (TMS) tolerant genotypes. Methods: Two experiments were conducted at experimental fields of Department of Genetics and Plant Breeding, University of Agricultural Sciences Bengaluru during 2017 post rainy season. The first experiment consisted of 33 genotypes which included 31 selected genotypes from F3 populations and two released varieties. The second experiment consisted of 13 genotypes which included 5 advanced breeding lines, 2 released varieties and 6 land races. The genotypes of both the experiments were evaluated for dry seed yield under two moisture regimes (MR), namely, MSF and TMS environments in separate trials following Randomized Block Design. Conclusion: Based on the criterion of significant correlation of indices with dry seed yield under both MSF and TMS environments, two indices namely, mean productivity (MP) and geometric mean productivity (GMP) were found desirable to identify TMS tolerant genotypes of both the experiments. Based on rank mean of the two indices, two F3 selections and one released variety from first experiment; four landraces, one advanced breeding line and one released variety from second experiment were found TMS tolerant.