Estimation of Heterosis and Combining Ability for Improving Yield, Sweetness, Carotenoid and Antioxidant Qualities in Pumpkin Hybrids (Cucurbita moschata Duch. Ex Poir.)

Abstract

A full diallel mating design was used to hybridize seven pumpkin inbred parental lines, yielding 42 F1 hybrids, including reciprocals. The generated F1 hybrids, parental lines and commercial check hybrid were evaluated in two environments to investigate the per se performances, combining ability effects and magnitude of heterosis over mid-parent, better-parent and commercial check hybrids for yield and attributed sweetness, total carotenoid and antioxidant traits, using a randomized complete block design with three replications. The analysis of variance for most of the examined traits revealed highly significant differences (p ≤ 0.01) for GCA, SCA, reciprocal, maternal and non-maternal variances and their interaction with the environment. Since the inheritance of yield and its contributing fruit quality, and antioxidant traits is governed by non-additive gene action, it suggests heterosis breeding would be useful in obtaining further improvements in pumpkin. From the experiment, it was found that the paternal lines P1 (Gold Butter 315) for dry matter content and DPPH (%), P4 for total carotenoid content, P6 for fruit number per plant and P7 (Australia-1) for single fruit weight, fruit flesh thickness, yield per plant and total soluble solid were shown to be good general combiners. In respect to per se performance, combining ability effects and magnitude of heterosis over mid-parent, better-parent and commercial check, the cross P2 (928 Fuxiang) × P1 (Gold Butter 315) and P4 (Asian pumpkin) × P5 (Sarawak) for single fruit weight and yield per plant, the cross P5 (Sarawak) × P2 (928 Fuxiang) for fruits number per plant, P1 (Gold Butter 315) × P7 (Australia-1) and P1 (Gold Butter 315) × P6 (Sarawak) for total soluble solid and dry matter content, P7 (Australia-1) × P2 (928 Fuxiang) for total carotenoid content and P3 (Ser Bajadi) × P1 (Gold Butter 315) for DPPH (antioxidant) were identified to be highly significant positive specific combiners and the highest performers, and these crosses may be exploited as commercial hybrids.

The Combining Ability and Heterosis Analysis of Sweet–Waxy Corn Hybrids for Yield-Related Traits and Carotenoids

“…Both the parental lines and their hybrids showed broad ranges of variation. In most, a parent is regarded as a good general combiner if it has higher positive or negative substantial general combining ability (GCA) effects depending on the breeding objectives [ 49 ]. Inbreds with significant GCA effects for more than one trait are of great interest for breeding.…”

“…Parents with high × high, high × low, and low × low GCA effects on traits suggest the presence of additive, dominant, and epistatic gene effects, respectively. The genetic variation in the parents, as measured by the number of heterozygous loci of the parents resembled in the hybrid, may be responsible for the superior hybrids using high × low or low × low GCA effects as parents [ 49 ]. For instance, the negative SCA effect desired for the hybrid with short plant stature and earliness could be improved by using transgressive segregants from crosses involving low × low or high combinations of parents.…”