Improvement in Bitter gourd (Momordica charantia L.) for yield and quality attributing traits
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Date
2019-01-31
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Department of Horticulture (Vegetable & Floriculture), BAU, Sabour
Abstract
Bitter gourd (Momordica charantia L.) is an important cucurbitaceous crop belonging to the family cucurbitaceae and is widely grown in Asia, Africa, and the Caribbean for its fruit. Bitter gourd being rich in all the essential vitamins and minerals, especially vitamin A, B1, B2, C and iron, its regular intake prevents many complications such as hypertension, eye complications, neuritis and defective metabolism of carbohydrates. It increases body's resistance against infection. The crop is highly cross pollinated due to its monoecious nature. The genetic variability, heritability, genetic advance, character association and path analysis for qualitative and quantitative characters were carried out in 21 accessions. The experiment was laid out in randomized complete block design with 3 replications in years, (Feb-June) 2015, (Feb-June) 2016 and (Feb-June) 2017.Significant variation was observed among most of the genotypes for all the traits under studied. High PCV along with high heritability, and genetic advance were observed for fruit weight, vitamin C, carotenoid and total phenol content whereas high PCV along with moderate value of genetic advance was observed for days to 1st fruit harvest, fruit length, fruit fly infestation, number of seeds/fruit, flavonoid, iron and fruit yield/plant. The correlation analysis for morphological traits revealed that all the traits were positively correlated with yield per plant at both genotypic and phenotypic level except node number to 1st staminate flower, node number to 1st pistillate flower, days to 1st staminate and pistillate flower anthesis, days to 50% flowering and days to 1st fruit harvest. The correlation analysis for biochemical traits revealed that all the traits were negatively correlated with yield per plant except Vitamin C, total chlorophyll, total phenol and iron both at genotypic and phenotypic level. Path analysis revealed that lowest positive direct on yield per plant was observed for fruit fly infestations. Negative direct effect on yield per plant were recorded on node number to 1st staminate flower, internodal length, no. of primary branches/vine, days to 1st fruit harvest, days to 1st pistillate flower anthesis, node no.to 1st pistillate flower, days to 1st staminate flower anthesis, vine length, number of seeds/fruits. The indirect path analysis for morphological traits revealed that characters fruit diameter had maximum positive indirect effect via fruit weight (1.128), fruit length (0.911), vine length (0.745), days to 50% flowering (0.223), number of fruits/vine (0.174) and fruit fly infestations (0.142). Days to 1st pistillate flower anthesis had maximum positive indirect effect via fruit weight (1.095), node number to 1st pistillate flower (0.582), node number to 1st staminate flower (0.640), days to 1st pistillate flower anthesis (0.381) and days to 1st fruit harvest (0.369). The indirect path analysis for biochemical traits revealed that characters total Phenols had maximum positive indirect effect via flavonoids and acidity. Chlorophyll a had maximum positive indirect effect via Vitamin c, total sugar, flavonoids, chlorophyll b, acidity and total phenol. Residual effect of path analysis was very low (0.7339) suggesting inclusion of maximum yield influencing characters in analysis.
The multivariate analysis according to Tocher’s method revealed that genotype was grouped into five clusters depending on their genetic divergence Cluster I had maximum number (11) of genotypes closely followed by cluster II (7). Cluster III, IV and V consists of only 1 genotypes. These accessions were further analyzed by multilocus RAPD and ISSR marker system. Combined data analysis of RAPD (17) and ISSR (11) markers provided 73.66 % polymorphism with 5.33 polymorphic amplicons per primer. The better discriminatory power of ISSR markers over RAPD markers may be due to comparatively higher values of average polymorphic information content (PIC;0.175), gene diversity (0.213) and allele frequency (0.814) as well as the diverse nature of the genotypes. The clustering of the both RAPD and ISSR marker divided the genotypes into five different sub-cluster.
Some genotypes i.e. BRBTL, BRBTW, Pusa Aushadhi, Karela Safed, Gangajalee small and Pusa Rasdar were selected based on molecular and morphological diversity of genotypes. Random crosses were made and their heterotic effects had estimated. BRBBTL x Pusa Aushadhi and BRBTL x Gangajalee small had shown significant heterotic effects for most of the traits in terms of better parent and standard parent.
Genetic effects of both qualitative and quantitative traits of both crosses of bitter gourd were studied using generation means analysis in six populations including P1, P2, F1, F2, B1 and B2 generations of cross BRBTL x Pusa Aushadhi and BRBTL x Gangajalee Small. Significant parental difference was observed for all the traits in both the crosses. Scaling test indicate significant additive, dominance and non-additive gene action were responsible for most of the traits. The cross BRBTL x Pusa Aushadhi exhibits additive × dominance (j) and dominance × dominance (l) were highly significant for most of the traits whereas the additive(d), dominance (h) and additive x dominance (j) had found significant in cross BRBTL x Gangajalee Small.