Browsing by Author "Noru Raja Sekhar Reddy"

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    Locating superior segregants with high yield and drought tolerance in yard long bean [Vigna unguiculata ssp. sesquipedalis (L.) Verdcourt]
    (Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, 2024-10-22) Noru Raja Sekhar Reddy; Beena Thomas
    Yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt), a member of Fabaceae, holds a significant position among legume vegetable crops. Climate change induced drought can significantly impact its cultivation, yield, and production. Among abiotic stresses, drought is severe and affects the quality of the pods, reducing their size and nutritional content, ultimately leading to decreased growth and yield. This study was entitled “Locating superior segregants with high yield and drought tolerance in yard long bean (Vigna unguiculata ssp. sesquipedalis (L.) Verdcourt)”. The study was conducted in Department of Genetics and Plant Breeding at College of Agriculture, Vellayani, from 2022 to 2024. The research comprised of three main experiments: evaluation of F2 segregants in the field, a laboratory analysis of screening of F3 seeds for drought stress tolerance using PEG, and evaluation of F3 segregants in the field. The previous Ph.D. research work entitled “Gene action and gene expression analysis in yard long bean (Vigna unguiculata ssp. sesquipedalis (L). Verdcourt) for drought tolerance” done in the Department of Genetics and Plant Breeding, College of Agriculture, Vellayani formed the materials of research work. The materials consisting of 200 seeds of yard long bean collected from F1 segregants from the cross of Katampally Local (Drought tolerant) ×Vellayani Jyothika (High yielding) were used for the present study. The collected 200 F2 segregants were evaluated for yield and various yield-related traits from September to December 2023. The seeds were sown at a spacing of 1.5 m х 0.45 m, and cultural operations were adopted as per the “Package of Practices Recommendations Crops 2016” of Kerala Agricultural University. From five superior segregants (F2-3, F2-79, F2-106, F2-130, and F2-184) the seeds were collected named as F3-1, F3-2, F3-3, F3-4, and F3-5. The collected seeds were used for laboratory experiment to assess drought tolerance by inducing osmotic stress in the laboratory. In the laboratory experiment, these five segregants were further assessed under drought stress conditions using two concentrations of PEG 6000 (-0.75 bar and -1 bar). Based 88 on germination percentage, root length, and seedling vigour index-I, F3-1 and F3-3 were identified as drought tolerant genotypes. The second field experiment (season - 2) involved the evaluation of the F3 segregants in a compact family block design with five progenies and five replications from February to May 2024. The seeds were sown at a spacing of 1.5 m х 0.45 m. The analysis of variance between families revealed that the mean sum of squares due to families was significantly different for all traits except pod width among all five families. The Bartlett’s test for homogeneity of error variances of five families indicated that error variances were homogenous for all characters except pod length, pods per plant, yield per plant, and crop duration. Genetic parameter analysis performed for five F3 families in traits like pod length, pod weight, pods per plant, yield per plant, and crop duration showed high phenotypic and genotypic variation, along with high heritability and genetic advance, indicating their suitability for selection. In the present investigation, the correlation studies indicated a significant positive correlation was shown by the characters like, pod weight, pods per plant, pod length, pod width, and harvest index with yield per plant. However, days to 50% flowering, crop duration, and vine length showed a significant negative correlation with yield per plant. Path analysis of the eight characters showing significant correlation with yield per plant revealed that the pod weight (1.09) and harvest index (1.03) exhibited a very high direct effect on yield per plant. The highest direct effect on yield per plant was shown by days to 50 % flowering (0.87) and pod width (0.79). A high indirect effect on yield per plant was shown by pod weight (3.32) through vine length. In conclusion, in field experiment (season-1) of evaluation of F2 segregants for yield and other related traits, genotypes F2-3, F2-79, F2-106, F2-130, and F2-184 were identified as superior for yield and other related traits out of 200 segregants. Genotypes F3-1 and F3-3 were identified as drought tolerant ones based on germination percentage, root length, and seedling vigour index-I in the laboratory experiment. In field experiment (season-2) of evaluation of F3 segregants for yield and other related traits, among five F3 families, F3-1 was identified as superior for yield and other related parameters. Within each family, superior progenies were progeny-1 (F3-1), progeny-1 89 (F3-2), progeny-2 (F3-3), progeny-3 (F3-4), and progeny-4 (F3-5). Based on the laboratory study, F3-1 was recognized as a superior segregant with drought tolerance. In field experiment, progenies from the F3-1 family showed high yield. These F3-1 segregants can be used in future breeding programmes for varietal development of yard long bean with high yield and drought tolerance.