1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Author: search.filters.author.Lasima Jahan, M S.Subject: search.filters.subject.Cucurbitaceae

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    Characterization and evaluation of selected genera under cucurbitaceae for drought tolerance
    (Department of Agricultural Vegetable Science, College of Agriculture,Vellanikkara, 2024-03-18) Lasima Jahan, M S.; Sangeetha Kutty, M
    Cucurbits comprise an extensive category of vegetables cultivated worldwide, playing a crucial role in the daily dietary intake of a large global population. The Cucurbitaceae family encompasses numerous genera and stands as the most extensive tropical vegetable group. This important family of vegetables comprises 950 species across more than 90 genera, predominantly found in tropical and subtropical regions (Parvathi et al., 2022). Cucurbitaceae family exhibits a remarkable genetic diversity, enabling them to thrive in a wide range of climates, including temperate regions, arid deserts, and tropical or subtropical zones (Rai et al., 2008). Despite their wide adaptability and widespread utility across the globe, cucurbits face increasing risks due to climate change, resulting in both biotic (living organism-related) and abiotic (non-living, environmental) stresses. Drought is one of the major limiting factors that significantly reduces crop output and results in both economic and nutritional insecurity (Wang et al., 2022). The present study entitled ‘Characterization and evaluation of selected genera under cucurbitaceae for drought tolerance’ was conducted at the Department of Vegetable Science, College of Agriculture, Kerala Agricultural University, Vellanikkara. The study was conducted from September to March and May to July of the academic year 2022-2023. Two experiments made up the current study. In the first experiment, 27 genotypes of cucurbits were characterized. It included eight genotypes of Luffa acutangula (LA-1 to LA-7), one Luffa cylindrica (LC-1), six Cucumis melo var. momordica (CMM-1 to CMM-6), two Lagenaria siceraria (LS-1 and LS-2), one Cucumis melo var. conomon (CMC-1), three Cucumis melo var. callosus (CC-1 to CC-3), one Cucumis melo var. utilissimus (CMU-1), one Momordica charantia var.muricata (MCM-1), two Cucurbita moschata (CM-1 and CM-2), one Cucumis sativus (CS-1) and one Citrullus lanatus (CL-1). During the study, observations were made on vegetative and reproductive characteristics, fruit and yield attributes, bitterness, as well as pest and disease incidence. Variations were noted among the species for all these parameters. In the second experiment, twenty genotypes from the first experiment were evaluated for drought tolerance in a pot culture experiment. The genotypes used in the study were LA-1, LA-2, LA-4, LA-8, CMM-2, CMM-4, CMM-5, CMM-6, CC-1, CC-2, CC-3, CS-1, CMU-1, CMC-1, MCM-1, LS-1, LS-1, CM-1 and CM- 2. Biochemical, physiological and morphological response of plants to drought stress were recorded in this study. The proline content and DPPH free radical scavenging activity exhibited different ranges among the genotypes of different species. In all genotypes, the proline content and DPPH free radical scavenging activity was observed to increase under drought conditions compared to control conditions. Cucumis melo var momordica (CMM-2, CMM-4, CMM-5 and CMM-6), Cucumis callosus (CC- 1, CC-2, and CC-3) and Momordica charantia var. muricata (MCM-1) had high proline content and DPPH free radical scavenging activity under water deficit when compared to well watered condition. All genotypes exhibited a reduction in total chlorophyll content under drought stress. Less reduction in chlorophyll content was seen in Cucumis melo var momordica (CMM-2, CMM-4, CMM-5 and CMM-6), Cucumis callosus (CC-1, CC-2, and CC-3) and Momordica charantia var. muricata (MCM-1). Water deficit leads to stomatal closure, a decreased transpiration rate, and an increase in leaf temperature. The change in photosynthesis rate, transpiration rate, stomatal conductance and leaf temperature was lower in Cucumis melo var momordica (CMM-2, CMM-4, CMM-5 and CMM-6), Cucumis callosus (CC-1, CC-2, and CC-3) and Momordica charantia var. muricata (MCM-1). Cucumis melo var momordica (CMM-2, CMM-4, CMM-5 and CMM-6), Cucumis callosus (CC-1, CC-2, and CC-3) and Momordica charantia var. muricata (MCM-1) exhibited higher root length and root weight under water deficit compared to well watered condition. Lower reduction under stress, in shoot length, as well as fresh and dry weights, were also observed in these genotypes, indicating their capacity for drought tolerance. These twenty genotypes of cucurbits were grouped into four clusters based on selected physiological and biochemical characters, using R software. The cluster III had the highest number of genotypes (8), followed by cluster IV (5). Cluster III consisted of the drought tolerant genotypes viz. CMM-2, CMM-4, CMM-5, CMM- 6, CC-1, CC-2, CC-3 and MCM-1. Thus, the present study reveals that Cucumis melo var momordica (CMM-2, CMM-4, CMM-5 and CMM-6), Cucumis callosus (CC-1, CC-2, and CC-3) and Momordica charantia var. muricata (MCM-1) are tolerant to drought. Hence there is a vast scope for further utilization of these genotypes in breeding as well as grafting programs.