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

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    Evaluation of Chilli (Capsicum annuum L.) genotypes for yield, bacterial wilt and leaf curl virus incidence
    (Department of Vegetable Science, College of Agriculture , Vellanikkara, 2024-05-21) Suvarna, K; Anitha, P
    Chilli is one of the important vegetable spice cultivated worldwide and is commonly referred to as red pepper or hot pepper. It is a crucial commercial crop utilized as a vegetable, spice, condiment and culinary flavour enhancer. Chilli is mainly used as culinary supplement to add flavour, colour and pungency. Chilli is an abundant source of vitamin A and C. Capsaicin and its related compounds present in the placental tissue of its fruits is used in pain relieve balms and vapour rubs. The green fruits of chilli stand out as one of the most plentiful sources of antioxidants. Despite its considerable nutritional value, widespread acceptance among consumers and extensive genetic diversity, achieving optimal productivity in chilli production remains a challenge due to lack of high-yielding and disease-resistant varieties or hybrids. In addition, diseases like chilli leaf curl virus and bacterial wilt are the most two important diseases affecting chilli production. In this context, the current study was initiated with the objective of assessment of morphological traits of chilli genotypes for yield to identify high yielding ones and to simultaneously evaluate these genotypes against bacterial wilt and leaf curl virus incidence. The present study was conducted in the Department of Vegetable Science, College of Agriculture, Vellanikkara during January 2023 to May 2023, using 31 chilli genotypes. The analysis of variance among the 31 genotypes of chilli revealed significant variations across all the traits. Genetic parameters such as Genotypic Coefficient of Variation (GCV), Phenotypic Coefficient of Variation (PCV), heritability and Genetic Advance (GA) were computed to assess the extent of variability. High GCV and PCV were exhibited by the characters like plant height, fruits per plant, average fresh fruit weight, average dry fruit weight, fruit length, fruit girth, pedicel- fruit ratio, yield per plant, bacterial wilt incidence, incidence of leaf curl virus, oleoresin content, capsaicin content, ascorbic acid content. The results indicated that the presence of a broad genetic base which will be useful in further selection. High heritability coupled with high genetic advance was reported in most of the morphological and quality characters indicating that these characters are under the influence of additive gene action. Therefore, it is feasible to apply direct selection for improving these traits. Correlation studies indicated that fruit yield per plant was significantly and positively correlated with plant height, primary branches per plant, fruits per plant, average fresh fruit weight, average dry fruit weight, fruit length, pedicel length, oleoresin content, capsaicin content and ascorbic acid content. Interrelationships among plant traits is crucial for enhancing both yield and quality. Hence, simultaneous selection for these characters would be advantageous for enhancing chilli yield. Path coefficient analysis among yield and its constituent traits indicated that the fruits per plant, average fresh fruit weight, days to harvest, pedicel length, fruit girth and plant height showed direct positive influence on yield. Path analysis reveals whether the correlation between yield-related traits and yield is having direct effect, in which case direct selection for improvement is possible. From the present study, based on the path coefficient and correlation results the genotypes CA 1, CA 3, CA 6 and Ujwala were recognized as promising or advantageous. The 31 chilli genotypes were categorized into eleven clusters using Mahalanobis D2 statistic. Cluster I contained the largest number of genotypes (21), followed by cluster II, cluster III, cluster IV, cluster V, cluster VI, cluster VII, cluster VIII, cluster IX, cluster X and cluster XI which had one genotype each. The intra-cluster distance was the highest in cluster I, while the inter-cluster distance was the greatest between cluster IV and cluster IX. Hence, selecting genotypes for hybridization or developing hybrids, genotypes from these two clusters should be prioritized. The selection index for chilli was established based on the characters including fruit yield per plant, fruits per plant, average fresh fruit weight, incidence of leaf curl virus and bacterial wilt incidence. Among the genotypes evaluated, CA 3, CA 6, CA 1 and Ujjwala were identified as the top performers. Notably, genotypes CA 3, CA 6 and CA 1 exhibited superior performance in terms of yield and leaf curl virus resistance when compared to Ujwala.
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    Evaluation of F2 segregating population of chilli (Capsicum annuum L.) for yield and resistance to leaf curl virus
    (Department of Vegetable Science, College of Agriculture, Vellayani, 2022-06-20) Archa, P S; Lekshmi, S L
    The project entitled “Evaluation of F2 segregating population of chilli (Capsicum annuum L.) for yield and resistance to leaf curl virus” was carried out at the Department of Vegetable Science, College of Agriculture, Vellayani, during summer 2021 to evaluate the F2 segregants of chilli crosses for yield and leaf curl virus resistance. In the present study two crosses viz., CHIVAR-6 x Sel-4 and CHIVAR-10 x Sel-3 were selected from the previous PhD research study conducted at the Department of Vegetable Science, College of Agriculture, Vellayani. The F2 population comprising of 200 segregants from the two crosses along with their parents were raised and evaluated for various characters and incidence of leaf curl virus. The results revealed variability among the segregants for various characters studied. Among the segregants maximum plant height was exhibited by C-2-182 (146.00 cm). The segregants of first cross, C-1-19, C-1-37, C-1-49, C-1-111, C-1-125, C-1-127, C-1-130, C-1-140 and C-1-163 were the earliest to flower (32.00 days).The days to harvest ranged from 51 days to 58 days among the segregants of the first cross and 52 days to 58 days in the second cross. The fruits per plant was highest in the segregant C-2- 161 (160) and C-1-149 (103) from both populations. Among the segregant population, maximum fruit length was noticed in the segregant C-2-42 (10.16 cm) of cross 2 whereas maximum fruit girth was noticed in C-1-145 (5.03 cm) of cross 1. Fruit pedicel length was highest in the segregant C-2-68 (4.49 cm). C-1-70 recorded the highest fruit weight (6.21 g) among the segregant population of the two crosses. C-2-70 had the maximum number of seeds per fruit of 119.00. Among the F2 population, the highest fruit yield per plant was exhibited by the segregant C-2-161 (518.79 g) followed by C-2-168 (420.40 g), C-1-117 (374.18 g) and C-1-151 (363.00 g). The ascorbic acid content ranged from 36 mg 100 g-1 to 144.00 mg 100 g-1 among the segregants. The highest carotenoid content was observed in C-1-196 and C- 2-112 (275.67 mg 100 g-1). In the present study, the scoring for chilli leaf curl virus was done and based on the scoring the segregants were categorized into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible. The coefficient of infection revealed that both the F2 segregants and their parents displayed highly resistant reaction to leaf curl virus. Enzyme analysis assay for peroxidase activity ranged from (12-37) unit activity1min-1 g -1 among the population of the cross 1 and in cross 2, it ranged from (11-47) unit activity-1min-1 g-1. Phenylalanine ammonia activity ranged from (15.3 µg-1 g-1min-1) to (28.2 µg-1 g-1min-1) and from (12.6 µg-1 g-1min-1) to (15.4 µg-1 g-1 min-1) in cross 1 and cross 2 respectively. Polyphenol oxidase activity of the segregant population of cross 1 ranged from 19-32 unit activity-1 min-1 g-1 and in the segregant population of cross 2 it ranged from 14-23 unit activity-1min-1 g -1 . The highest percentage of positive segregants in the F2 population of the cross CHIVAR-6 x Sel-4 was observed for days to first flowering (78 %), yield per plant (52 %), fruits per plant (40.5 %) and seeds per fruit (34.5 %). In the cross CHIVAR-10 x Sel3, highest positive segregation percentage was observed for plant height (81.5 %), yield per plant (69.5 %) and fruits per plant (56.5 %). Principal component analysis was carried out for the quantitative characters. Out of the thirteen principal component axes (PCA)s extracted, six PCAs with eigen values greater than one were retained for both the cross which accounted for total variation of 64.07 per cent and 67.31 per cent in the cross 1 and cross 2 respectively. The first two principal components contributed major part of the variation with a proportion of 16.78 per cent and 11.79 per cent in cross 1. In the second cross first two components contributed 18.95 per cent and 12.66 per cent respectively. Based on simple correlation study for various characters with yield per plant it was observed that for the F2 population of CHIVAR-6 x Sel-4 significant positive correlation was observed for fruits per plant (0.718), plant height (0.292), fruit weight (0.286) and fruit girth (0.16). F2 population of CHIVAR-10 x Sel-3 exhibited significant positive correlation for fruits per plant (0.818), plant height (0.286) and fruit length (0.184) with yield per plant. In case of the parents of cross 1 significant positive correlation was shown for fruits per plant (0.406). The chi-square analysis for goodness to fit to various gene interaction ratios revealed that the segregating population of cross 1 fitted to the ratio 12:3:1 for fruit surface. The segregants of the cross 2, fitted for the ratio 3:1 for fruit shape at pedicel attachment, 9:6:1 for fruit shape at blossom end and 9:3:4 for fruit surface character. The chi-square analysis for leaf curl virus resistance revealed that the observed ratio in the segregants holds a good fit to the ratio 3:1. The test results shows that the genetics of resistance is governed by a single dominant gene in both the crosses. Based on the yield and leaf curl virus incidence, the segregants C-2-161, C-2-168, C-1- 117, C-2-10, C-2-154 and C-1-151 were found to be superior and are suitable for further segregation studies.