| This research was undertaken to estimate the heritabilities of, and genetic correlation between, various traits related to growth habit in two populations of tropical pumpkin (Cucurbita moschata by estimating variance and covariance components.;Two populations were used in this study. Puerto Rico Synthetic 3 (PRSYN3), a broad based population and PRB150, an elite population. Evaluation of PRSYN3 was conducted in 1993 and 1995 and PRB150, in 1993 only. A reps-in-sets design with four replications was used. Thirty two S1 families were evaluated in PRB150 and 112 half-sib families in PRSYN3.;Flowering date of the first pistillate flower, vine length, number of nodes and average internode length measured from the crown to the first pistillate flower and number of lateral branches within 25 cm of the crown were measured in both populations. In addition, fruit number, fruit weight and yield were determined in PRSYN3.;Plant growth was more vigorous and yields were higher in 1993 than in 1995. Over populations and years the heritabilities for days to flower and fruit weight were always intermediate (near 50%) while that of internode length was usually intermediate. None of the traits from the combined analysis of population PRSYN3 planted in 1993 and 1995 manifested any significant heritabilities.;Phenotypic correlations among traits studied in both populations were similar. Genetic correlations were more variable between populations and between years within PRSYN3. Most of the correlations in the over years combined analysis of PRSYN3 were weak.;The results suggest that there is limited genetic variation for the traits analysed in PRSYN3. It is important to test population PRB150 in other environments. |
