Combining ability and heterosis analysis for growth, yield, and yield-related traits in watermelon (Citrullus lanatus) under arid conditions

Exploitation of heterosis has substantially enhanced watermelon productivity; however, information on the combining ability of genetically diverse parental lines under hot arid environments remains limited. Identifying superior parental lines and hybrid combinations through combining ability and heterosis analysis is essential for watermelon improvement, particularly under hot arid environments where such information remains limited. Analysis of variance revealed significant differences among genotypes for all thirteen traits across both seasons, indicating substantial genetic variability. Both additive and non-additive gene effects were shown to be involved by significant general combining ability (GCA) and specific combining ability (SCA) mean squares for every characteristic. BIL-53, AHW/YF Selection-1, AHW/YF Selection-2, and Thar Tripti were found to be valuable breeding parents due to their improved GCA impacts for marketable fruit yield per plant and other commercially significant features. The hybrids Thar Tripti × Arka Shyama, Arka Shyama × AHW/YF Selection-1, and Arka Shyama × AHW/YF Selection-2 recorded up to 71.6% better marketable fruit output per plant than the commercial control by combining high per se performance with significant SCA effects and superior standard heterosis. Additionally, these hybrids performed well in terms of fruit number, average fruit weight, and earliness, demonstrating their potential for hybrid production in hot, dry climates. The study demonstrated the importance of both additive and non-additive genetic effects in the inheritance of growth and yield traits in watermelon. The parental lines BIL-53, AHW/YF Selection-1, AHW/YF Selection-2, and Thar Tripti emerged as promising donors for hybrid breeding, while the hybrids Thar Tripti × Arka Shyama, Arka Shyama × AHW/YF Selection-1, and Arka Shyama × AHW/YF Selection-2 were identified as superior combinations for developing high-yielding, climate-resilient watermelon hybrids adapted to hot arid environments.