Genetic analysis and heterotic performance of bitter gourd hybrids under the temperate Himalayan Region

Introduction

Bitter gourd (Momordica charantia L.) is an important vegetable belonging to family cucurbitaceae. The fruits are bitter in taste owing to the presence of an alkaloid 'momordicine' which is different from cucurbitacin present in other cucurbits. It has high nutritive value an is used in herbal medicine systems because of its disease preventing and health promoting phyto-chemical compounds like dietary fiber, vitamins, flavonoids and antioxidants. Together, these compounds help act as protective scavengers against oxygenderived free radicals and reactive oxygen species (ROS) that play a role in aging, cancers and degenerative disease. Bitter gourd has large variability and its sex expression is monoecious and as such can be profitably utilized through commercial exploitation of heterosis for the production of hybrids. There is a need to exploit the naturally endowed diversity in bitter gourd to develop hybrid varieties. Line  tester (Kempthorne, 1957) [9] biometric design is useful in preliminary screening of large number of lines and crosses for their general and specific combining ability effects, components of genetic variance and heterosis. Keeping in view the above facts the present investigation was carried out to exploit the heterosis in Bitter gourd for earliness and quality. NDBG-12, NDBG-17, Pant Karela-1 and PBTH-52 were crossed with three testers viz; Arka Harit, Jounpuri and Local Bitter gourd to generate thirty crosses following line x tester mating design (Kempthorne, 1957) [9] . The set of thirty crosses along with their parents (10 lines and 3 testers) were evaluated in RCBD with three replications at three locations viz., Vegetable Experimental Farm, Division of Vegetable Science, SKUAST-Kashmir, Shalimar, central Kashmir (E1); Faculty of Agriculture, Wadura, North kashmir (E2) and KVK Malangpora, South Kashmir (E3). The observations were recorded on twelve traits viz., node to first male flower appearance, node to first female flower appearance, days to anthesis of first male flower, days to anthesis of first female flower, days to first fruit harvest, total carotenoids (mg 100g -1 ), total phenols (mg100g -1 ), total chlorophyll (mg 100g -1 ), iron content (mg 100g -1 ), vitamin-C content (mg 100g -1 ), dry matter (%) and dietary fibre content (%).Five randomly plants in each treatment over the replications were selected and labelled and were used for recording the observations. The average of the five plants was taken for analysis Analysis of variance for each of the character in randomized block design was performed utilizing the technique of Fisher and Yates (1938). The magnitude of heterosis was estimated in relation standard check values. They were thus, calculated as percentage increase or decrease of F1s over standard parent (S.P.) using the methods of Turner (1953) and Hayes et al. (1956) [13,7] .

Results and Discussion

Analysis of Variance

In the present study the analysis of variance (Table 1 & 2) revealed that mean squares due to lines, testers, crosses and line × tester were significant for node to first male flower appearance, node to first female flower appearance, days to anthesis of first male flower, days to anthesis of first female flower, days to first fruit harvest, total phenols (mg100g -1 ), total chlorophyll (mg 100g -1 ), iron content (mg 100g -1 ), vitamin-C content (mg 100g -1 ), dry matter (%) and dietary fibre content (%) in pooled analysis. This depicted the presence of significant variability among parents and crosses and the diverse lines upon crossing with testers produced substantial variability among crosses. For total carotenoids (mg100 g -1 ) mean squares due to crosses were significant while mean squares due to various other sources of variation were non-significant which indicates that less variability was found within the parents for this trait. This implied that the variability has been created by crossing programme for total carotenoids as depicted by significant mean squares due to crosses. The mean squares due to parents vs crosses were significant for all the traits under study except total carotenoids which indicated the possibility of sufficient amount of heterosis exploitation for these traits. However for total carotenoids, the nonsignificant mean squares due to parents vs crosses implies that there is no scope for heterosis exploitation in the present experimental material. The interactions resulting from lines x environment, tester × environment, crosses x environment and line × tester ×environment were non-significant for the traits except dietary fiber. The similar studies were carried by Kundu, B.C et al. 2021 [10] for earliness in bitter gourd; Acharya, S.K et al. 2019 [1] in bitter gourd for earliness and Vitamin C content; Mallikarjunarao et al. (2018) [11] for ealiness and quality in bitter gourd; Kaur and Dhall, 2017 [8] for various earliness and yield traits in cucumber;

Heterosis for Earliness

Earliness is an important trait in bitter gourd to realize the potential economic yield in less time which is an important consideration for a vegetable grower. The earliness was measured as node to first male and female flower appearance, days to anthesis of first male and female flower and days to first fruit harvest. The results from table 3 depicts the heterosis over standard check, Arka Harit for earliness. For node to first male flower appearance the significant desirable negative heterosis over standard parent was observed in NDBG-1 × Arka Harit (-5.37%), NDBG-3 × Jounpuri (-3.73%) and NDBG-7 × LBG (-2.98). For node to first female flower appearance the crosses NDBG-17 × Jounpuri (7.25%) NDBG-7 × Arka Harit (-4.62%), NDBG-7 × LBG (-4.45%), NDBG-3 × Jounpuri (4.04%), NDBG-5 × Jounpuri (-3.23%) and NDBG-1 × Arka Harit (-2.89%) showed desirable negative significant heterosis over standard parent. For days to anthesis of first male flower, twenty three crosses showed desirable negative heterosis over standard parent. The maximum desirable negative standard heterosis was reported in NDBG-17 × Jounpuri (-14.20%), NDBG-7 × Arka Harit (-8.53%), NDBG-6 × LBG (6.98%), NDBG-4 × LBG (6.92%), NDBG-12 × LBG (-6.89%), NDBG-5 × Jounpuri (-6.65%), NDBG-5 × Arka Harit (-6.30%), NDBG-12 × Arka Harit (-6.21%) and NDBG-17 × LBG (-6.18%). For days to anthesis of first female flower nineteen crosses showed desirable negative heterosis over standard parent with maximum in NDBG-17 × Jounpuri (-15.53%), NDBG-17 × LBG (-8.92%), NDBG-12 × LBG (-5.94%), NDBG-7 × Arka Harit (-5.91%), NDBG-4 × Arka Harit (-5.83%), NDBG-12 × Arka Harit (-5.60%) and NDBG-12 × Jounpuri (-5.16%). For days to first fruit harvest the desirable negative significant heterosis over standard parent was observed in eleven crosses. The maximum standard heterosis was observed in NDBG-17 × Jounpuri (-14.36%), NDBG-17 × LBG (-4.70%), NDBG-12 × LBG (-3.43%), NDBG-12 × Arka Harit (-2.95%), NDBG-1 × LBG (-1.86%) and NDBG-4 × Arka Harit (-1.75%). The similar studies on earliness traits were conducted by Amrita Kumari et [3,1,11,5,6,2] .

Heterosis for Quality traits

Perusal of the results (Table 4) revealed that for total carotenoids the maximum desirable standard heterosis over check Arka Harit was reported in NDBG-4 × Arka Harit (65.67%), NDBG-4 × LBG (50.00%), NDBG-3 × Arka Harit (44.03%), NDBG-4 × Jounpuri (41.79%) and NDBG-1 × Arka Harit (36.57%). For total phenols the desirable heterosis over standard parent was observed in NDBG-6 × Jounpuri (6.60%) and NDBG-4 × Jounpuri (4.59%). For total chlorophyll content, thirteen crosses showed significant desirable standard heterosis with maximum in NDBG-1 × Arka Harit (35.33%), NDBG-1xJounpuri (30.89%), NDBG-6 × Jounpuri (23.82%), PBTH-52 × Jounpuri (22.22%), NDBG-7 × LBG (21.42%) and NDBG-12 × Arka Harit (17.96%). For iron content the desirable maximum significant standard heterosis was observed in NDBG-7 × Arka Harit (39.58%) followed by NDBG-12 × Arka Harit (6.25%) and NDBG-4 × Arka Harit (4.17%). For Vitamin-C none of the crosses showed desirable significant heterosis over standard parent. For dry matter content seven crosses showed desirable significant heterosis over standard parent with maximum in NDBG- [3,11,2,12] . The results from table 5 depicts the best cross combinations for various traits with respect to desirable heterosis and good per se performance. Crosses NDBG-17 × Jounpuri, NDBG-17 × LBG, NDBG-12 × LBG and NDBG-12 × Arka Harit reported desirable significant negative standard heterosis along with good per se performance for maximum earliness traits. NDBG-4 x Arka Harit and NDBG-4 x Arka Harit showed high desirable standard heterosis along with good per se performance for maximum quality traits.

Conclusion

Analysis of variance revealed significant differences among the parents and crosses for almost all the traits under study indicating that the materials selected for present investigation were diverse. The mean squares due to parents vs crosses were significant for all the traits (except total carotenoids) which indicated the possibility of sufficient amount of heterosis exploitation for these traits.The extent of heterosis exhibited by crosses were estimated over standard parent Arka Harit. For Earliness traits, crosses NDBG-17 × Jounpuri, NDBG-17 × LBG, NDBG-12 × Local bitter gourd, and NDBG-12 × Arka Harit possessed desirable negative significant standard heterosis along with good per se performance. Crosses viz: NDBG-4 × Arka Harit and NDBG-1 x Arka Harit showed desirable significant positive heterosis for maximum quality traits. The best crosses in terms of standard heterosis with good per se performance especially for earliness could be considered for commercial exploitation in bitter gourd.

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