Abstract
The average yield of pumpkin in Bangladesh is very low as compared to that in other tropical countries. This low yield may be due to lack of high yielding varieties and high incidence of disease, pests and also due to minimum use of hybrid seeds. Therefore, the present study was undertaken with three separate experiments during the period of April, 2014 to March, 2017 to study the diversity among 30 pumpkin genotypes considering thirteen yield and yield contributing traits for developing pumpkin yellow vein mosaic virus (PYVMV) resistant hybrid pumpkin. The field experiments were conducted at the Research and Development (R&D) Farm of ACI Seed at Rural Development Academy (RDA), Bogura, Bangladesh. In the mean square performance of the genotypes, highly significant variation of all the genotypes for all yield and yield contributing characters were observed. The genotypes CM-13, CM-14, CM-18, CM-15 and CM-12 showed the desirable earliness in female flowering. CM-14 had the highest number of fruits per plant and was closely followed by CM-13, CM-12, CM-9 and CM-17. CM-28 and CM-12, CM-15, CM-14 and CM-7 showed desirable yield/plant. From the study of genetic parameters, high heritability coupled with high genetic advance in percent of mean suggested the presence of major role of additive gene action. The correlation analysis indicated that different yield and yield contributing characters were inter correlated and they had positive association with fruit yield per plant. The result of path analysis revealed single fruit weight and fruits per plant were the major contributors to yield per plant. On the basis of clustering analysis, 30 genotypes were grouped into five clusters. Selected from clustering study, pairings between these groups (IV & V, III & V, II & III, II & IV) were more divergent and more important for heterotic breeding program. Out of 30, seven genotypes viz., CM-2, CM-5, CM-12, CM-14, CM-15, CM-25 and CM-28 were selected based on screening against PYVMV and virus specific primer based PYVMV detection for 7 X7 half diallel cross for developing resistant hybrid pumpkin. This result indicated that the selected PYVMV resistance seven pumpkin genotypes were more divergent and more important for heterotic breeding program. Estimation of general combining ability effects showed that parent CM-28 was good general combiner for most of yield contributing traits followed by CM-12, CM-15, CM-14 and CM-25. The SCA effects showed that F1 (CM-12 x CM-25) was good specific combiner followed by F1 (CM-28 X CM-25) and F1 (CM-15 X CM-14). For heterosis study, the mid parent, better parent and check variety, the combination F1 (CM-12 X CM-25) was the most promising hybrid (F1) for most of the traits followed by F1 (CM-28 X CM-25), F1 (CM-15 X CM-14), F1 (CM-28 X CM-12) and F1 (CM-28 X CM-14). After confirmation of resistance against PYVMV (screening under field condition and PCR based detection) five crosses were resistant to PYVMV and considering yield, percent of heterosis, fruit size, shape, color and present market demand of the studied cross combinations, the combination F1 (CM-12 X CM-25), F1 (CM- 28 X CM-25), F1 (CM-15 X CM-14) might be recommended for farmers' cultivation for better performance particularly for yield.