GENETIC ANALYSIS OF YIELD AND YIELD CONTRIBUTING TRAITS IN PUMPKIN (Cucurbita moschata Duch. Ex. Poir)

Abstract

The present research program was undertaken to study the genetic analysis of yield and yield contributing traits of pumpkin (Cucurbita moschata Duch. ex Poir.). All experiments were conducted at R & D Farm, Lal Teer Seed Limited, Gazipur, Bangladesh. The present study includes genetic diversity study, interrelationships among yield components, combining ability, heterosis, and heritability of yield and yield related traits. Direct and indirect effects of the traits to yield were also analyzed. Detailed gene actions were studied in selected four crosses for yield and yield contributing characters. The tested genotypes exhibited wide range of variation on different yield and yield components. Among twenty one genotypes of pumpkin, six performed better in respect of different yield components and quality characters. For all traits, genotypic coefficient of variation (GCV) was always smaller than phenotypic coefficient of variation (PCV). Narrow differences between GCV and PCV and high heritability coupled with high genetic advance (GA) confirmed least environmental effects on fruit length, single fruit weight, brix content and yield per plant which offered better scope of selection for variety improvement program of pumpkin. Based on the degree of divergence among genotypes, the twenty one genotypes were grouped into six clusters. Out of these, six different divergent inbred parents (CM-20, CM-1, CM-5, BARI Mistikumra-1, CM-8 and CM-14) were selected using ranking on variance among genotypes within cluster for 6X6 diallel cross including reciprocals. Yield per plant, at phenotypic and genotypic level, was significantly and positively correlated with fruit length, fruit diameter, single fruit weight, flesh thickness, number of fruits per plant and 100-seed weight. These components had the maximum contribution towards total divergence. The direct effect of single fruit weight was very close to correlation value at phenotypic and genotypic level. Thus selection was done through single fruit weight and number of fruits per plant. Studies on interrelationships among yield and yield components revealed that genetic correlation coefficient was higher than corresponding phenotypic ones for all the characters studied, thereby establishing strong inherent relationships among them. Path coefficient analysis showed that single fruit weight had maximum direct effect on yield per plant followed by number of fruits per plant, days to female flower per plant, fruit diameter, number of seeds per fruit and number of female flowers per plant both at genotypic and phenotypic levels. Significant GCA variance was recorded for days to male and female flower opening, fruit length and diameter, single fruit weight, number of fruits per plant, number of seeds per fruit, 100 seed weight, brix content and yield. Both additive and non-additive effects influenced the performance of the hybrid for all traits. Four parents (CM-1, BARI Mistikumra-1, CM-20 and CM-8) were found as good general combiners. Obtaining significantly higher and positive heterosis and expected negative effects for different important characters of pumpkin, two cross combinations namely, CM-1 X BARI Mistikumra-1 and CM-8 X CM-1 were identified as the promising hybrids commercial utilization. Thus, these two hybrids were approved and registered as Hajee F1 and Danesh F1 respectively by NSB, MOA of Bangladesh. Indigenous X Exotic crosses showed significant greater heterosis for yield and its components. Broad sense heritability of all the 13 characters was above 90% indicating high heritability since the expression of yield and its components were controlled by additive, dominance and different epistatic gene interactions which can be used in desirable direction for varietal improvement program of pumpkin.