Investigation of gene effects on Fruit Shape Index and Seed Size in Generations Resulting from The Crossing of Zucchini and Hull-Less Seed Pumpkin
Abstract Fruit shape index (round shape) and seed size have important effects on pumpkin yield. To investigate these traits and create the most desirable state, a cross was made between two pumpkin cultivars. The objective of this study was to estimate the main gene effects (additive, dominant and di-genic epistasis) and to determine the mode of inheritance for fruit shape and seed size by generation mean analysis. Six generations, namely P1, P2, F1, F2, BC1, and BC2 from a cross between Zucchini and hull-less seed Pumpkin, S10×P25, were constructed and evaluated for fruit length, fruit width, fruit shape index, and some seed-related traits (seed length, seed width, seed thickness). The experiment was conducted in the research field of the Faculty of Agricultural Science, University of Guilan, Rasht, Iran in 2019. Results showed a significant difference between generations in terms of fruit and seed traits. Scale and joint scale tests showed the presence of epistasis for some traits. According to the results of the average traits of different generations, standard heterosis and hetrobeltiosis were observed. Concerning the fruit shape index and seed width, there was an over-dominance effect. The broad-sense heritability of the traits was relatively high for all traits and between 52 and 92%. Narrow sense heritability was between 26 and 86% and relatively low for the fruit shape index and seed width. Therefore, selection of elite lines and production of their hybrids are recommended as two methods suitable for breeding to achieve the round shape index and larger seed size.