Genetic Variability and Divergence Studies in Cucumber (Cucumis sativus L.)

Author: Harshita R. Patel, Rehana Niyaria, K.G.Modha, Vaishali J. Ahir and Hardik R. Patel

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Abstract

Genetic variability in a crop population is important for successful plant breeding. An experiment was conducted to study Genetic variability, heritability, genetic advance and genetic divergence for some traits in Cucumber (Cucumis sativus L.). The experiment was carried out at the Rajendrapuara Farm, Hill Millet Research Station, Navsari Agricultural University, Waghai (The Dangs), Gujarat during the summer 2019 using twenty-five cucumber genotypes including the checks, Shubhangi and Himangi, in Randomized Block Design with three replications. The analysis of variance revealed significant differences among genotypes indicating presence of sufficient amount of variability in all the characters studied except days to last fruit harvest and moisture content. Magnitudes of GCV and PCV were found high for primary branches per plant, Node number of first male flower and seeds per fruit. Whereas, moderate GCV and PCV were recorded for fruit length, yield per vine, fruit girth, node number of first female flower, fruit weight, total sugar content and vine length. High heritability coupled with high genetic advance was observed for the traits viz., node number of first female flower, node number of first male flower, primary branches per plant, vine length, fruit length, fruit weight, fruit girth, seeds per fruit, yield per vine and total sugar content. The magnitude of genotypic correlations was recorded higher as compared to corresponding phenotypic correlations for majority of the traits under study indicating that there was an inherent association between these characters at genotypic level. Path coefficient analysis revealed the highest positive direct effect on yield per vine by primary branches per plant, followed by fruit girth, total sugar content, days to first fruit harvest, ascorbic acid content, seeds per fruit, days to first male flower, moisture content, node number of first female flower, internodal length and node number of first male flower. The D2 analysis indicated presence of ample genetic diversity among the genotypes studied, which were grouped into seven clusters through Mahalanobis D2 statistics. Cluster V contained the maximum (6) number of genotypes, whereas cluster VI and cluster VII contained minimum (1) genotype only. The intra cluster D2 value ranged from 0.00 (Cluster VI and Cluster VII) to 29.07 (Cluster VI). The inter cluster D2 values of the seven clusters revealed that highest inter cluster distance (512.39) was between cluster II and cluster VI

Keywords

Variability, heritability, Correlation, Path analysis and D2

Conclusion

To conclude, the analysis of variance for all the traits revealed differences among the genotypes studied, indicating sufficient amount of variability present among twenty-five genotypes under study. High heritability was also coupled with high genetic advance as per cent of mean for these traits, which indicated the predominance of additive gene effects, thus more emphasis should be given to mass selection and progeny selection for further improvement of these characters. Yield per vine showed highly significant and positive correlation with node number of first female flower, node number of first male flower, internodal length, primary branches per plant, vine length, fruits per vine, fruit length, fruit weight, fruit girth, seeds per fruit, total sugar content and ascorbic acid content at both genotypic and phenotypic levels while days to last fruit harvest at genotypic level only. These revealed that due weightage should be given to these traits during selection to improve the yield in cucumber whereas, yield per vine showed highly significant and negative correlation with days to first female flower, days to first male flower and days to first fruit harvest. There is no need of direct selection in trait which showed negative correlation with yield because it decrease the yield. Path coefficient analysis showed the positive direct effect on yield per vine was recorded by primary branches per plant, fruit girth, total sugar content, days to first fruit harvest, ascorbic acid content, seeds per fruit, days to first male flower, moisture content, node number of first female flower, internodal length and node number of first male flower. Hence, these traits were considered as the most important yield contributors and due emphasis should be given while attempting yield improvement in cucumber. D2 analysis indicated wider genetic diversity among the twenty five genotypes, which were grouped in seven different clusters. Cluster V comprised of 6 genotypes, Cluster I and cluster II comprised of 5 genotypes, cluster IV comprised of 4 genotypes, cluster III comprised of 3 genotypes and remaining cluster (VI and VII) comprised of single genotype. (monogenotypic). The maximum inter cluster distance was observed between cluster II and cluster VI. From the results, it will be stated that inter-crossing from cluster II and cluster VI genotypes might result in wide array of variability for exercising effective selection

References

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How to cite this article

Harshita R. Patel, Rehana Niyaria, K.G. Modha, Vaishali J. Ahir and Hardik R. Patel (2024). Genetic Variability and Divergence Studies in Cucumber (Cucumis sativus L.). Biological Forum – An International Journal, 16(3): 114-121