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Subject: Vegetable Science × Author: Kaur, Manpreet × Start date: 2020 × Type: Thesis ×
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    ThesisItemOpen Access
    Genetical studies in parthenocarpic cucumber (Cucumis sativus L.)
    (palampur, 2022-05-21) Kaur, Manpreet; Sharma, Parveen
    The present investigation entitled “Genetical studies in parthenocarpic cucumber (Cucumis sativus L.)” was carried out at the Experimental Farm, Department of Vegetable Science and Floriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur to gather information on combining ability, gene action and magnitude of heterosis in parthenocarpic cucumber. Eight parental lines were used to develop F1 hybrids through half diallel mating design (excluding reciprocals). All parental lines and hybrids were evaluated along with standard check Kian in RBD with three replications under modified naturally ventilated polyhouses during spring-summer seasons of 2020 and 2021. Genetic diversity of eight parental lines was assessed using SSR markers to identify the diverse parents. PCA revealed 54.04 per cent variation as justified by first three principal components and maximum genetic variation (21.10%) was contributed by PC1. Eight cucumber genotypes were grouped into two clusters and both the clusters were divided into 2 sub clusters (NTSYS software) and DARwin software exhibited three clusters out of which cluster II was further divided into two sub clusters and was also confirmed by population structure. The analysis of variance indicated significant differences among genotypes (G) for fruit yield and other component traits in all the environments. Significant differences for environment (E) and G × E interaction for most of the traits indicated the role of environment on the performance of genotypes/crosses. Combined analysis of variance also indicated that mean squares due to parents, hybrids and parents vs. hybrids were significant for most of the traits. Variances due to GCA, SCA and their interaction with environment were significant for most of the traits, indicating the importance of testing parents as well as hybrids across environments. The top cross combinations identified on the basis per se performance were DDPCG1 × DDPCG2, DDPCG1 × DDPCG5, DDPCG1 × PPC-2 and DDPCG1 × PPC-3 for fruit yield and its component traits under protected environment. Parents DDPCG1, DDPCG4, PPC-2 and DDPCG5 were observed to be good general combiners for earliness, fruit yield and its component traits. Cross combinations viz., DDPCG4 × DDPCG5, DDPCG1 × PPC-2, DDPCG1 × DDPCG5, PK-1 × PPC-3 and DDPCG1 × DDPCW1 were the most promising crosses on the basis of SCA effects for yield and its related traits. For most of the traits, there was preponderance of non-additive gene action which reaffirms the importance of hybrids in cucumber. A wide variation in magnitude and direction of heterosis was noticed for majority of the traits with maximum manifestation for number of fruits per plant and marketable yield per plant. Hybrids DDPCG1 × DDPCG2, DDPCG1 × DDPCG5, DDPCG1 × PPC-2, DDPCG1 × PK-1 and DDPCG1 × DDPCW1 were the most promising crosses with significant economic heterosis for yield and yield related traits. Based on per se performance, SCA effects and heterosis, DDPCG1 × DDPCG2, DDPCG1 × DDPCG5, DDPCG1 × PPC-2, DDPCG1 × PK-1 and DDPCG1 × DDPCW1 were the most promising hybrid combinations for protected environment