MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF CITRULLUS SPECIES AND STUDIES OF INTER SPECIFIC HYBRIDISATION

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Date
2016
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DIVISION OF VEGETABLE SCIENCE INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
This investigation was carried out to analyze genetic variability and extent of genetic diversity in 102 genotypes of Citrullus species on the basis of morphological traits and molecular marker analysis. The germplasm was evaluated for resistance against bud necrosis disease under field condition to identify sources of resistance and utilize them in development and characterization of inter-specific hybrids. The experiment was laid out in a randomized block design with three replications. Analysis of variance showed significant differences for all characters which reflected presence of high magnitude of variability for all the yield and nutritional characters among the watermelon germplasm utilized for this study. High phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for node number of first male flower (58.38, 56.67), yield per plant (57.37, 52.76), average fruit weight (44.98, 43.79), manganese (57.49, 55.79), copper (56.62, 55.95) and zinc (54.73, 53.69) contents, respectively which reflected wide variability for traits of economic importance and further selection could improve the genotypes. Moderate to high heritability coupled with high genetic advance as per cent of mean were found for average fruit weight (97.22, 90.08), yield per plant (76.39, 90.28), Zn (86.26, 97.25) and Mn (82.93, 98.21) content. Five genotypes DWM 152, Sugar Baby, DWM 19, DWM 171and DWM 113 can be used directly in the breeding programme for improvement of different yield traits. Principal components analysis suggested that average fruit weight, fruit length, fruit diameter, flesh thickness, fruit yield and number of fruits per plant were the major characters for discrimination of 102 Citrullus genotypes which could be classified into two major clusters. Fifty three Citrullus germplasm could be classified into two clusters at 48 % similarity based on SSR markers. All 12 wild Citrullus genotypes were grouped in cluster I and 41 genotypes from cultivated types were grouped in cluster II. Three Citrullus genotypes DWM 30, DWM 55 and DWM 210 (C. colocynthis) could be identified as highly resistant to bud necrosis disease under field condition. Inter specific hybrid between Sugar Baby and DWM 210 also exhibited highly resistant reaction against bud necrosis disease which indicates that DWM 210 (C. colocynthis) can be utilized as source of resistance for introgression of genes into cultivated varieties in future breeding programmes.
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T-9483
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