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

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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.
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    DNA barcoding in genera benincasa and praecitrullus
    (Centre for Plant Biotechnology and Molecular Biology, College of Horticulture,Vellanikkara, 2019) Priya Sonkamble; Narayanankutty, C
    Benincasa is a monotypic genus with only one cultivated species hispida. In India, Benincasa exhibits rich diversity. There is substantial variation in vegetative traits and fruitcharacters and it is difficult to distinguish ashgourd genotypes based on their external morphology alone. In spite of having enormous morphological variability, all members at present are accommodated into asingle species. The taxonomic classification of Praecitrullus is still uncertain. The marker and pollen morphology studieshave revealed that P. fistulosusis more related to B. hispida, than compared to other cucurbit species. DNA barcoding is a novel system designed to provide rapid, accurate and automatable species identification using short, standardized genomic regions as internal species tags. DNA barcoding is based on the characteristic variations on the sequences of identified genomic regions, which can distinguish individuals of a species. Species identification through barcoding is usually achieved by the retrieval of a short DNA sequence from a standard part of the genome (i.e. a specific gene region either from chloroplast, mitochondria or nuclear genome) and identifying the barcode gaps for each species. The barcode sequence from each unknown specimen is then compared with a library of reference barcode sequences derived from individuals of known identity. The study entitled “DNA barcoding in genera Benincasa and Praecitrullus was done at Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara, with the objectives to assess genetic diversity and interspecies relationship among Benincasa and Praecitrullus genotypes and to check the species status of Benincasa using barcodes. Twenty-six ashgourd and five tinda accessions were morphologically screened in the field using the standard descriptor and basedaccessions were clustered, based on morphological characters recorded. The ashgourd accessions varied widely for their morphological traits,fruit size varied between0.191 to 12.0 kg. Thefruit shape, varied from club, spindle, cylindrical, oblong to ridged shape. The growth habit varied from long viny to short viny.Serrated, deep serrated and double serrated leaf margin was observed. For stem pubescencevariations recorded were hispid, downy, tomentose, puberulent, pilose,villous and hirsute. The cross compatibility of the ash gourd accessions were also checked to establish the species status. All the accessions of ash gourd were cross compatiblein both the directions, showing that they belong to the same species. Based on the morphological data of ashgourd accessions nine cluster were generated. One representative accession from each cluster and three representative accessions of tinda selected for the molecular studies. Total genomic was isolated and subjected to PCR assay. The matK and ITS2 gave the bands of 950 bp and 799 bp respectively, which were sufficient to identify barcode gaps.The markers were sequenced from 9 genotypes of ashgourd and 3 tinda genotypes.The BLAST analysis had shown that matK and ITS2 both loci is 99 per cent efficient for species discrimination in Benincasa and Praecitrullus. Barcode gap, a position in the sequence at which a particular nucleotide shows characteristic variation in all the members of a particular species, was identified for all the members of Benincasa and Praecitrullus species. Barcode gaps were identified for tinda, in comparison with Benincasa for both the loci. The barcodes in tinda were observed in matK locus at 47, 127 and 232bp. Similarly, for the locus ITS2, the barcode gaps in tinda were identified at 162, 207, 278, 279 and 288 bp. However, within Benincasa, there were no such characteristic barcode gaps, indicating that the null hypothesis of monotypic status of Benincasa is true. Phylogenetic analysis using Clustal Omega showed the variation within Benincasa species and Praecitrullus species.The barcodes developed in this study could be successfully used to solve the genetic relatedness of Benincasa and Praecitrullus species.
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    Development of tropical gynoecious lines in cucumber (Cucumis sativus L.)
    (Department of Olericulture, College of Horticulture, vellanikkara, 2016) Karthika, A K; Pradeepkumar, T
    The present study ‘Development of tropical gynoecious lines in (Cucumber sativus L.) was carried out at Department of Olericulture, College of Horticulture, Kerala Agricultural university, Vellanikkara, Thrissur during August - November 2014 and February - May 2015 to evaluate the F1 hybrids and their F2 population for identifying stable tropical gynoecious lines of salad cucumber. Twelve hybrids produced by crossing gynoecious line EC 709119 with selected tropical monoecious parents were evaluated for gynoecy under rainshelter. Observations on important quantitative and qualitative characters were recorded. These hybrids were selfed to generate F2 population. F2 population was evaluated for expression of gynoecious character, viz., days taken for female flower anthesis, node at which first female flower emerged and total number of female flowers. The data was subjected to analysis of variance and variability among the genotypes was calculated. Most of the characters exhibited high heritability except for fruit parameters like fruit length, fruit girth and flesh thickness. For gynoecy F2 population from the cross EC 709119 x IC 538186 was observed as the most promising one. This population took only minimum days to form female flower and took minimum number of nodes to form female flower with highest number of female flowers and minimum male flowers. Sex ratio was estimated for parents, F1 hybrids and F2 population. Some of the parents having high sex ratio failed to transmit the same to its hybrid progenies. Among the parents, IC 538186 exhibited highest sex ratio. The highest sex ratio among the F2 population was for EC 709119 x IC 538186. Two populations viz., EC 709119 x IC 527427 and EC 709119 X IC 538186 exhibited a sex ratio of more than 2. The 4 F2 population evaluated for gynoecious trait were classified into monoecious and gynoecious character and tested for goodness of fit based on chi square test with monohybrid ratio of 3:1 being monoecy dominant over gynoecy. Out of the 4 populations, 2 populations were found to express significant value and fit in 3:1 ratio for dominant monoecious trait. The other 2 populations failed to fit in the 3:1 ratio. Bitterness was an important quality character which was absent in most of the parents except three of them during initial harvest. The crosses involving parents prone to bitterness were found to be bitter during later harvest, though all crosses were free of bitterness during initial stage. During later harvests, five parents were found to be bitter. Downy mildew incidence on parents and F1 hybrids were analyzed and Percentage of Disease Intensity (PDI) was estimated. Among parents, IC 538186 exhibited minimum infection and falls under the category of moderate resistance. Hybrid, EC 709119 x IC 538186 exhibited minimum infection and falls under the category of moderate resistance. Among 12 F2 populations, EC 709119 x IC 538186 produced maximum number of true gynoecious plants whereas eight F2 populations failed to produce even one true gynoecious plant. This population also exhibited moderate resistance against downy mildew disease and could be selected for developing true breeding stable gynoecious line for future breeding programme. Present investigation proved the scope of developing tropical gynoecious line from temperate lines by crossing with potential-monoecious lines and making selection in advance segregating generations for gynoecy.
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    Standardisation of micropropagation technique in ivygourd (Coccinia grandis (L.) Voigt.) variety sulabha
    (Department of Vegetable Science, College of Agriculture, Vellayani, 2019) Thasni, A; Sarada, S
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    Integrated management of viral diseases of bittergourd (momordica charantia L.)
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Radhika, N S; Umamaheswaran, K