Genetic variation, trait interrelationships and cluster analysis in indigenous sponge gourd (Luffa cylindrica L. Roem.) germplasm of Assam

Morpho-metric characterization of sponge gourd germplasm revealed polymorphism in 12 qualitative traits. Primary branches per plant, internode length, peduncle length, fruit length, fruits per plant, seeds per fruit and marketable fruit yield per plant registered high genotypic and phenotypic coefficients of variation. The heritability in broad sense and expected genetic advance as percent of mean were high for all the traits except vine length. The genetic correlation of marketable fruit yield per plant was highly significant and positive with primary branches, internode number, fruit length, female flowers per plant, fruits per plant and fruit weight. Marketable fruit yield had a significant negative genetic correlation with internode length, days to the appearance of first male flower, days to the appearance of the first female flower, node number at which first female flower appears, days to first fruit harvest, fruit diameter and male-female flower ratio. Genetic path analysis revealed high direct effects of fruits per plant and fruit weight on marketable fruit yield. An Unweighted Neighbour-Joining (UNJ) clustering based on usual Euclidean distances grouped the sponge gourd germplasm into three distinct clusters. The information accrued may be useful in sponge gourd improvement.