ESTIMATION OF GENETIC PARAMETERS IN PIPIANA SQUASH (Cucurbita argyrosperma Huber)

Abstract

This study was done to generate information related with genetic parameters for two populations (one with and other without selection) of pipiana squash C. argyrosperma Huber var. stenosperma and C. argyrosperma Huber var. argyrosperma), regarding: mean, additive variance, dominance variance, heritability, coefficient of additive variation, phenotypic and genotypic correlations of 13 traits. The experiments were conduced at Chapingo, México in 2001, at two plant densities per experiment: D1, 13 890 and D2, 9 260 plants/ha of squash associated with maize (Zea mays L.) (50 000 plants/ha), in alternated rows of each plant species. The results indicated that in the two populations the additive variance and the genetic additive variation coefficient (CVA) were higher for fruit seed weight. Heritabilities oscillated from 17.2 to 62.4 % in the ‘Morelos’ variety (VM), and in ‘Chapingo’ variety (VCH) they varied from 23.0 to 91.9 %. A higher dominance variation was found in ‘Morelos’ than in ‘Chapingo’, and the highest genetic correlations were registered among weight and seed length (VCH = 0.55**; VM = 0.70**), and seed length and flesh thickness of with 0.50** for both varieties. The highest phenotypic correlations among traits occurred for fruit weight and fruit width (VCH = 0.82**; VM = 0.85**) and for fruit weight with seed weight in VCH = 0.75** and VM = 0.74**, respectively.