PhD Thesis
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Item Generation mean analysis in yard long bean (Vigna unguiculata subsp.sesquipedalis (L.) Verdcourt) for yield and mosaic resistance(Vegetable Science, College of Agriculture, Vellayani, 2024-02-13) Airina, C K.; KAU; Sarada, SThe present study ‘Generation mean analysis in yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) for yield and mosaic resistance ' was undertaken at the department of Vegetable Science, College of Agriculture, Vellayani, Thiruvananthapuram during 2017-2019 and at Pepper Research Station, Panniyur, Kannur during 2022-23 to develop high yielding and mosaic resistant yard long bean hybrids and to study the inheritance and gene action of yield and mosaic resistance using generation mean analysis. Seventy six cowpea genotypes were screened against the blackeye cowpea mosaic virus (BlCMV) to ascertain the disease reaction of the genotypes by artificial inoculation under pot culture method. Based on the extent of symptoms and vulnerability index (VI), three genotypes were found highly resistant, 11 genotypes showed resistant response, 13 genotypes were moderately resistant, 10 genotypes moderately susceptible, 20 genotypes susceptible and remaining 18 genotypes showed a highly susceptible reaction. The genotypes Manjari, VU-7 and EC-18734 were highly resistant to BlCMV. Five high yielding yard long bean genotypes viz; Vellayani Jyothika, Vyjayanthi, Geethika, KAU Deepika, and KAU Mithra which gave a susceptible response were selected as lines and three genotypes, viz. Manjari, VU-7 and EC-18734, which gave an immune response as testers for the development of 15 hybrids in a line x tester fashion. The hybrids and their eight parents were raised with a standard variety Lola and resistant check Manjari in a randomized block design with three replications in open field in Rabi 2022 and were tested for 19 yield characters and mosaic resistance. The mean squares due to parents were highly significant for all the characters, while for hybrids significant difference was observed for all the characters except pod girth and yield per plot. The PCV values for all the characters were found to be higher than the GCV values but in smaller magnitude, which implied a lesser influence of environmental factors for these characters. The PCV and GCV values ranged from 3.31 to 52.80 and 2.06 to 51.68, respectively. Heritability estimates expressed in percentage ranged from 26.00 % to 97.80 % and estimates of genetic advance ranged from 2.63 to 104. The genotypic correlation coefficients were higher in magnitude than that of phenotypic correlation coefficients for most of the traits under study, which clearly indicated the presence of inherent association among various characters. For yield per plant, significant positive correlation was estimated with vine length, pod length and pod weight, whereas significant negative correlation with branches per plant, days to first flowering and days to harvest. Significant GCA effects were recorded for all the characters except pod girth. Among the lines, KAU Deepika showed good general combining ability for days to first flowering, pod length, pod weight, 100 seed weight, yield per plant, yield per plot, days to harvest and keeping quality and among the testers, Manjari exhibited good GCA effect for vine length, pod length, pod weight, seeds per pod, pods per plant, yield per plant, yield per plot and keeping quality. Significant SCA effects were observed for 13 quantitative characters viz; vine length, primary branches per plant, terminal leaf length, terminal leaf width, lateral leaf length, lateral leaf width, days to first flowering, pod length, pod weight, 100 seed weight, and days to harvest, pod protein and keeping quality. Vyjayanthi x EC 18734, KAU Deepika x Manjari and KAU Mithra x Manjari were good specific combiners for pod weight and Vellayani Jyothika x EC 18734, Vyjayanthi x EC 18734, Githika x VU7 and KAU Deepika x Manjari for 100 seed weight. Desirable significant standard heterosis has been identified for 12 characters studied viz; no. of branches per plant, terminal leaf width, lateral leaf width, days to first flowering, days to harvest, pod weight, pods per plant, yield per plant, yield per plot, 100 seed weight, pod protein content and keeping quality. The crosses KAU Deepika x Manjari and KAU Mithra x Manjari registered significant positive heterosis over mid, better, and standard parents for pod yield and high mid-parent heterosis and standard heterosis for pods per plant. The highest magnitude of standard heterosis was identified for pods per plant (101.14 %), followed by yield per plant (75.30 %). Besides the heterotic potential, the hybrid KAU Mithra x Manjari, KAU Deepika x Manjari and Githika x Manjari were resistant to mosaic disease. In field evaluation during Rabi 2022, among the three testers, Manjari alone exhibited an immune response (VI-0.00) for mosaic disease. Other major pests and diseases observed in the field were pod borer, pod bug, fusarium wilt and anthracnose. The three crosses Githika x Manjari, KAU Deepika x Manjari and KAU Mithra x Manjari were selected and six generations i.e. P1, P2, F1, F2, BC1 and BC2 of each cross were evaluated under open field conditions to study the inheritance and gene action of mosaic resistance and yield parameters. For mosaic resistance, the scaling tests were non-significant which implied that additive-dominance model was adequate in Cross I and II, while dominance x dominance epistasis was prominent in cross III. Predominance of dominant gene action was noticed in cross II and III for yield per plant, while dominance x dominance (l) action in cross I. Duplicate type of epistasis was also observed in cross I and III for the trait. Epistatic interactions were observed for all the characters, except vine length and number of branches per plant in cross I (Githika x Manjari), additive x dominance being prominent in most of the traits. Predominance of dominant gene or dominance x dominance (l) interaction was noticed in majority of the traits in cross II ( KAU Deepika x Manjari). Significance of both additive x additive (i) component and dominance x dominance component or either one of the component was identified for the inheritance of yield traits in cross III (KAU Mithra x Manjari). Duplicate type of epistasis was revealed for eleven characters viz; vine length, terminal leaf length, lateral leaf length, days to flowering, pod girth, pod weight, hundred seed weight, yield per plant, crop duration, protein content and keeping quality, of which eight were present in cross II. The yard long bean hybrid KAU Deepika x Manjari, with good general combining ability for yield characters, high heterotic potential, high yield and mosaic resistance was identified as the best cross from the study.Item Bio-ecology and management of borer pests infesting yard lond bean, Vigna unguiculata subsp. sesquipedalis (L.) verdc.(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Sontakke Pritin Pramod; Amritha, V S