Genetics of bacterial wilt (Ralstonia solanacearum) resistance and some quantitative and qualitative traits in sweet pepper

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Date
2007
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CSK Himachal Pradesh Krishi Vishavavidyalaya, Palampur
Abstract
ABSTRACT The present study was aimed to obtain information on the genetics of bacterial wilt resistance, morphological and biochemical traits. In addition, the information was gathered on the association of these traits with bacterial wilt resistance and on the extent of heterosis. Six generations (P1, P2, F1, B1, B2 and F2) of six crosses, evolved by utilizing two resistant (PBC-631 and IHR-546) and two susceptible parents (California Wonder and Yolo Wonder) were evaluated in a Randomized Block Design at the experimental farm of Department of Vegetable Science and Floriculture, CSK HPKV, Palampur and HAREC, Bajaura during summer, 2006. The genetics of bacterial wilt resistance was observed to be dominant in nature with the degree varying from incomplete to complete dominance. The crosses, PBC-631 x CW, PBC-631 x YW and IHR-546 x CW revealed the presence of monogenic dominance in the inheritance of bacterial wilt resistance, which was further confirmed from their test cross ratios (1R:1S). Sufficient genetic variability was generated through hybridization for all the morphological and biochemical traits. The presence of dominance components for yield per plant in all the crosses along-with complementary type of interaction in IHR-546 x YW suggested the exploitation of heterosis for yield per plant. Similarly, positive dominance genic effects recorded in most of the cross combinations for number of fruits per plant further indicated to exploit hybrid vigour. However, negative additive [d] component and positive additive x additive [i] component for average fruit weight in most of the crosses suggested to delay selection for improving this trait. In the present study, the nature and magnitude of gene effect varied with different crosses for most of the quantitative as well as biochemical traits. So, specific breeding strategy has to be adopted for a particular cross to get desired improvement. On the basis of correlation and path analysis studies ascorbic acid content, total sugars, reducing sugars, non-reducing sugars, ortho dihydroxy phenols and polyphenol oxidase activity played an important and crucial role in determining the resistance to bacterial wilt. YW x CW was found to be the most promising and consistent heterotic combination for yield per plant, number of fruits per plant, average fruit yield per plant, number of pickings and plant height, however, this cross was highly susceptible to bacterial wilt. Since, the fruits of most of F1s were not bell shaped or blocky as preferred by the consumers, therefore, back-cross breeding programme with commercial cultivars accompanied by selection for bacterial wilt resistance is suggested.
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Doctoral Dissertation
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##Unable to generate tags mahboob_thesis.pdf, Vegetable science, ##Unable to generate tags mahboob_thesis.pdf, Sweet pepper
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