Inheritance of gynoecy, parthenocarpy and yield in cucumber (Cucumis sativus L.)
Loading...
Files
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Horticulture (Veg. Science), BAU, Sabour
Abstract
Cucumber (Cucumis sativus L.) is cross-pollinated and generally monoecious in nature but gynoecious lines are also present which can be utilized efficiently for commercial F1 hybrid production. Monoecious cultivars require pollen for fruit sets which are not suitable for protected cultivation however fruits of these cultivars are highly demanded by consumers because of their crispiness and tender fruits. In the contrary, gynoecious cultivars with parthenocarpic traits do not require pollen for fertilization and thus fruit development and help in off-season production under protected conditions. Gynoecious and parthenocarpic cultivars have been used in production, but their genetic mechanism in cucumber is not well understood with conflicting reports. Also, the stability of gynoecious with parthenocarpic traits is highly influenced by environmental factors. Therefore, the present investigation was carried out at the department of horticulture (Veg. & Flori.), BAC, BAU, Sabour to study the inheritance of gynoecy, parthenocarpy and yield in cucumber during August- December 2022 inside a naturally ventilated polyhouse in randomized block design with three replications. Data were recorded from 30 plants of parent P1, parent P2 and their F1, 120 plants of F2 and 60 plants each of BC1P1 and BC1P2 from three crosses namely BRGCU-4 × BRCU-1-13, BRPCU-8 × BRCU-1-13 and BRPCU-8 × BRGCU-4 for morphological and quality parameters. Generation mean analysis exhibited additive, dominance and epistasis gene effect was important in determining the inheritance of characters under study. Sex ratio was under the control of additive gene effect and non additive gene effect whereas for trait parthenocarpy per cent and yield per plant was under the control of non-additive gene effect. Additive gene effect indicated the significance of a fixable type of gene hence selection could be beneficial in early generations for these characters however dominance gene effect indicated the predominance of non fixable type of gene thus, to enhance the performance of the trait postpones the selection to later generations by reduction of heterozygosity. The existence of epistasis may be due to the participation of different alleles in the heterozygous state. Thus, population improvement by recurrent selection may be beneficial for the enhancement of these traits in a particular cross. Inbreeding depression was non-significant for number of nodes to first female flower, days to anthesis of first female flower, sex ratio, days to first fruit harvest, number of fruits per vine, fruit weight, fruit length, fruit diameter, vine length, yield per plant and firmness in all the crosses which reflects the low reduction in the mean of F2 generation due to direct effect of homozygosity. Based on potence ratio, over dominance was noted for fruit diameter which can be exploited for getting transgressive segregants. The result of χ2 analysis of field and molecular data suggested that the gynoecy in BRGCU-4 and BRPCU-8 were controlled by a single complete dominant gene which can be transferred to horticulturally desirable varieties through backcross breeding and parthenocarpy in BRPCU-8 was under the control of single incomplete dominant gene. SSR11610, UW084119, SSR11343 and SSR13251 markers were used for the screening of gynoecious lines whereas SSR21886, SSR11858, SSR13251, SSR07248, SSR19165 and SSR01148 markers used for the screening of parthenocarpic gynoecious lines from monoecious lines and SSR21886 and SSR07248 markers used for the screening of parthenocarpic gynoecious lines from gynoecious lines. Therefore, these SSR markers are of great significance to ascertain the purity of the gynoecious and parthenocarpic line at an early stage of development.