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

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Author: search.filters.author.Akshaya, RSubject: search.filters.subject.capsicum spp

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    Evaluation of chilli (Capsicum spp.) genotypes for mite resistance
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellanikkara, 2024-10-21) Akshaya, R; Asish, I Edakkalathur
    Chilli is an important crop which finds its use as vegetable, spice, ethnic medicine, cosmetics and in industry. Biotic and abiotic stresses impair chilli production and its quality. Among the biotic stresses, bacterial wilt and sucking pests are the major causes of concern. In summer months, there is drastic reduction in quality and quantity of chilli due to combined attack of thrips and mites which are often referred to as sucking pest complex. Sustainable, environment-friendly and cost- effective pest management strategy to combat mite pests is the development of mite resistant varieties. To achieve this, it is essential to identify resistant genotypes from germplasm and understand the host plant resistance mechanisms. In the above perspective, present study was conducted during October, 2021 to December, 2022 at College of Agriculture, Vellanikkara with the objectives of evaluation of chilli genotypes for resistance to mite (Polyphagotarsonemus latus Banks) and identification of biochemical characters associated with the mite resistance. The study comprised of two experiments. First experiment was germplasm evaluation for mite resistance and economic parameters. Materials used for the study included 71 genotypes collected from Department of Plant Breeding and Genetics, CoA, Vellanikkara, ICAR-NBPGR-RS Hyderabad, Nicobar lines received from ICAR-NBPGR-RS Thrissur, and farmers of Kerala. Genotypes were raised in augmented block design with five check varieties viz., Anugraha, Vellayani Thejus, Vellayani Samrudhi, Keerthi, and Arka Meghana during October, 2021 to May, 2022. Mite susceptible landrace Byadgi kaddi was raised around the field to ensure mite population in the field. Observations were recorded on primary leaf colour, days to flowering, immature fruit colour, fruit length (cm), fruit diameter (cm), fruit weight (g), number of fruits per plant and yield per plant (g). Many genotypes surpassed the superior check variety in above economic characters. Majority of accessions had green primary leaf and immature fruit. Number of leaves showing downward curling symptoms were recorded at 45, 60, and 75 days after transplanting (DAT) and Per cent Leaf curl Index (PLI) was estimated. Genotypes were grouped as resistant, moderately resistant, susceptible and highly susceptible based on PLI. Two genotypes viz., PbCa 445 and PbCa 446 were recorded as resistant and 12 genotypes viz., were recorded as moderately resistant. Except Keerthi, all varieties used as checks were recorded as susceptible or highly susceptible. Resistant and moderately resistant genotypes were forwarded to the next season for validation of resistance inside polyhouse. Fourteen resistant genotypes identified in the previous season were raised in polyhouse during July to December, 2022 for validation of resistance. Five most susceptible genotypes identified in the previous season were also raised for comparative study. Artificial inoculation was carried out at 25 DAT through leaf clipping method. PLI was estimated at 45, 60, and 75 DAT as in the first experiment to confirm the resistance reaction of selected genotypes. Genotypes viz., PbCa 445, PbCa 451, PbCa 417 and PbCa 446 were noted as least susceptible with average PLI of 30.00 to 36.67. All other genotypes including Keerthi were grouped as highly susceptible with average of PLI ranging from 62.22 to 91.11. Number of eggs and active stages of mites were recorded at 45, 60 and 75 DAT. Total number of eggs and active stages averaged on above three stages ranged from 14.07 to 170 per six leaves. Genotypes PbCa 445 and PbCa 451 were recorded with lowest average PLI of 30, whereas genotypes PbCa 446 and PbCa 451 were recorded with lowest total number of eggs and active stages of mite with values of 14.07 and 27.04, respectively. Non- glandular and glandular trichome densities were recorded from both abaxial and adaxial surfaces of leaf. Number of mite eggs, active stages and total mite number were positively correlated with density of adaxial non-glandular trichomes. Adaxial non-glandular trichomes in moderately susceptible genotypes ranged from zero to 28 per cent per square centimetre, whereas it was in the range of 5.67 to 100 in highly susceptible genotypes. Other types of trichomes were not associated with number of eggs or active stages of mite. Protein, sugar and phenol content were estimated from selected genotypes of which sugar showed negative correlation with PLI. Four moderately susceptible genotypes validated in the present study could be used in the further breeding programme. Selected genotypes may be crossed in diallel mating design and resultant F1 generation may be evaluated to know genetics of mite resistance and to obtain desirable genetic combinations having mite resistance and yield.