Topcross in supersweet corn doubled haploids for the formation of heterotic groups and hybrid selection1

ABSTRACT Doubled haploid technology is widely used in conventional corn to accelerate the development of inbred lines. This study aimed to estimate the combining ability of supersweet corn doubled haploid lines, identify new tester lines and establish heterotic groups. Two tester lines (LA and LB) were crossed with 28 doubled haploid lines of six supersweet corn populations using the topcross method and evaluated together with five checks for dehusked ear yield, ear diameter, plant height and soluble solids content. The growing seasons and treatments had significant effects on all the investigated traits, as well as season x treatment interaction on ear yield and diameter. The HA1, HB1, HB12, HB13, HB14, HB15, HB19, HB20 and HB22 hybrids exhibited a superior performance, with average yields ranging from 11.95 to 15.39 t ha-1, and were grouped with the commercial check and Test3. The LB and L19 lines showed the best general combining ability estimates for yield. There were significant specific combining ability effects for most variables. The lines obtained from the PD2005 and PD2006 populations were allocated to the same heterotic group as LB, and those from the synthetic populations SD3002 and SD3003 to the same group as LA. The L19 line shows potential of use as a tester for SD3005 lines.