Phenotypic profiling and identification of trait specific genotypes of seed purpose watermelon in Thar desert of India.

The seventh-biggest desert in the world, the Thar Desert, is home to a number of species that have adapted to the harsh desert environment. One of them seed purpose watermelon is an endemic, seed and vegetable purpose C3 cucurbitaceous xerophytes naturally grown from antiquity. Present investigation was undertaken to evaluate 138 seed purpose watermelon genotypes including three checks for phenology, fruits and seed yield related traits using multivariate approach. Analysis of variance revealed highly significant differences (p < 0.001) among the genotypes, blocks and its interaction for all the traits studied showed that a wide and significant variation existed among the genotypes and traits. Descriptive statistics revealed significant variation for days to fruit initiation (27-56 days), days to maturity (64-74 days), fruit diameter (66.07-129.50 mm), fruits per plant (1-5), fruit yield (40-248.25 q/ha), 100-seed weight (3.44-9.07 g) and seed yield (0.40-5.28 q/ha). The phenotypic coefficient of variation (PCV) was slightly higher than genotypic coefficient of variation (GCV) except for fruits per plant signifying little influence of environment on the expression of all the traits studied. High PCV and GCV were recorded for seed yield followed by fruit yield and fruits per plant indicating variation and scope of improvement through phenotypic selection. High heritability coupled with high genetic advance for all the traits except days to maturity revealed that they are predominantly governed by additive gene action and phenotypic selection will be effective. The highly significant positive associations (P < 0.01) of seed yield with fruit yield, fruits per plant, fruit diameter and 100-seed weight; 100-seed weight with fruit yield and days to maturity; fruit yield with fruits per plant and fruit diameter and fruits per plant with fruit diameter; implies that improving one or more component traits could result in genetic enhancement of seed yield in seed purpose watermelon. Cluster analysis for quantitative traits using unweighted pair group method of arithmetic averages (UPGMA) grouped the genotypes into eight clusters with varied number. The principal component analysis (PCA) revealed that most of the variation (99.91%) was accounted by first four PCA and fruit yield and fruit diameter have contributed most of the variation in dimensions 1 and 2. The extra early genotypes such as RMK2313, RMK2345 and RMK2353, RMK2324, multi-trait specific genotypes (fruits per plant, fruit yield and seed yield) viz., RMK23123, RMK23127, RMK23130 along with check GK-2, RMK2348 and RMK2365 for highest seed yield and RMK2355 exceptionally for both extra early and highest seed yield attributes could be used for selection or intercrossing in subsequent generations. This study identified the trait association among the different agro-morphological attributes and identified the trait specific genotypes in kalingada, which could help plant breeders select the best genotypes to improve fruit and seed yields.