Evaluation of sponge gourd genotypes for variability and quality

Abstract

Sponge gourd [Luffa cylindrica (L.) Roem syn L. aegyptiaca Mill] is a summer season vegetable which requires warm summer temperatures. It is an annual climber that yields fruit with a fibrous vascular system. Young fruits are edible, and mature fibres have industrial applications. Potential applications of this crop may literally be seen everywhere in fields including agriculture, medicine, science, engineering, and biotechnology.

Even though it has many medicinal and industrial applications, its cultivation is restricted to a limited area. Thus, there is a huge scope to expand its cultivation to non- conventional areas. Since, it is an underutilized vegetable in Kerala, it is very important to have knowledge on genetic diversity of the crop in formulating crop improvement program.

In this context, the present study was undertaken with the objectives of determining the genetic variability, correlation between yield and its components, and genetic divergence among sponge gourd accessions, as well as evaluating their quality. The experiment was carried out in Department of Vegetable Science, College of Agriculture, Vellanikkara during February 2022 – June 2022.

Wide variability was observed for the morphological characteristics of the sponge gourd accessions. Fruit colour varied from light green to dark green. Accessions IC-343160, IC-332319, IC-284881, IC-313018, IC-312949, Kashi Shreya, and the local collection showed a dark green colour with white stripes. Fruit shaped varied from elongate to elliptical among all the genotypes. IC-334305, IC-284946, and IC-433702 were elliptical in shape. The analysis of variance of the 20 genotypes of sponge gourd exhibited significant differences among them for all the traits under study. Genetic parameters like GCV, PCV, heritability and GAM were estimated to study the degree of variability. High GCV and PCV were exhibited by the characters like node number of first

staminate flower, number of primary branches per plant, number of fruits per plant, fruit yield per plant, calcium content, iron content, and fibre content, which implies the presence of a broad genetic base and will be useful in further selection. High heritability coupled with high genetic advance was reported in most of the morphological and quality characters indicating that these characters are under the influence of additive gene action.

Fruit yield per plant was significantly and positively correlated with number of primary branches per plant, fruit length, average fruit weight and number of fruits per plant, fibre content and shelf life. Therefore, simultaneous selection for these traits would be useful in improving the yield of sponge gourd. Path coefficient analysis between yield and its component traits revealed that number of fruits per plant, days to first marketable fruit harvest, average fruit weight, days to anthesis of first pistillate flower, number of primary branches per plant, node number of first pistillate flower and rind thickness exhibited direct positive effect on yield. Hence, direct selection for these traits would be useful to improve the fruit yield. From the present study, based on the above traits, accessions IC-343160, IC-332319, IC-312949, IC-343162 and IC-398587 were found good.

The 20 sponge gourd genotypes were grouped into seven clusters based on Mahalanobis D2 statistic. Cluster VII had highest number of genotypes (5) followed by cluster VI (4). Cluster I and III had three genotypes each. There were two genotypes in each of clusters IV and V and one genotype in cluster II. Intra cluster distance was maximum in cluster VII. Inter cluster distance was maximum between cluster I and III. Therefore, in hybridization program, genotypes should be selected from these two clusters for developing hybrids.

Sensory evaluation was conducted on the cooked as well as uncooked fruits in order to score them based on their appearance, colour, flavour, texture and overall acceptability. IC-312949, IC-343160, IC-332319, IC-284881 and IC-398579 were superior in sensory qualities. There was no bitterness in most of the accessions. The analysis of cucurbitacin E was done using HPLC, and the results showed that cucurbitacin E is absent in all the samples of sponge gourd.

The selection index for sponge gourd was fixed by taking the characters like fruit yield per plant, number of fruits per plant, average fruit weight, days to anthesis of the first pistillate flower, and overall acceptability of sensory evaluation and the accessions IC-343160, IC-332319, IC-312949, IC-284869, and Kashi Shreya were identified as the best ones. Genotypes IC-343160, IC-332319, IC-312949 outperformed the released variety Kashi Shreya of IIVR, Varanasi, with respect to yield and quality.