CAPACITY OF COMBINATION OF OBTAINED LINEAGES FOR THE METHOD OF DIHAPLOIDIZATION IN THE CORN CULTURE

Abstract

Nine inbred lines obtained by dihaploidization, were evaluated in a top cross with two testers of narrow genetic bases and the single-cross hybrids were tested in two location, at the Campos Gerais region, PR. The objective was to examine the General Combining Ability (GCA) and the Specific Combining Ability (SCA) of the lines obtained by haploidization and to verify how promising they are to obtain commercial competitive maize hybrids. The experiments were settled in randomized complete block design with three replications, including two commercial controls, as being the lines that compose these commercial hybrids used as controls. The experimental plots consist of two 5.0 m rows spaced at 0.8 m, with 62,000 density plants per hectare. The variables estimated were grain yield, plant height, ear height and resistance of the disease common rust (Puccinia sorghi). General and specific combining ability effects (GCA and SCA) were determined for the doubled-haploids lines. The treatments combined analyses showed high statistic significance (P<0.01) to GCA. However, the GCA of the controls showed only significant effects for grain yield and ear high. The statistical significant effect of the SCA was only showed for the plant high and ear high. The interaction Location x Treatment showed high statistic significant differences for all analyzed variables. The Location x F1s interaction showed high statistic significant differences for GCA for grain yield and ear high. The GCA of Testers x Location showed statistic significant effects for the plant high and the ear high. The SCA x Location interaction did not present statistic significant differences (P<0.01). These results showed greater influence of the additive gene effects. The lines showed a different behavior for each analyzed variable, with the major effects for GCA obtained within the lines L1, L2, L3, L4 and L7 and for SCA obtained within the crosses L5xT1 for grain yield, L3xT1, for plant hight, and L1xT2 for ear high. The controls GCA showed different behavior among treatments and locations.