Heterosis expression in crosses between maize populations: ear yield

Abstract

The phenomenon of heterosis has been exploited extensively in maize (Zea mays L.) breeding. The objective of this study was to evaluate the genetic potential of ten maize populations for ear yield following the diallel mating scheme. Six parental populations were obtained through phenotypic selection of open-pollinated ears in Rio Verde, GO, Brazil, (GO populations) and four parental populations were synthesized in Piracicaba, SP, Brazil (GN populations): GO-D (DENTADO), GO- F (FLINT), GO-A (AMARELO), GO-B (BRANCO), GO-L (LONGO), GO-G (GROSSO), GN-01, GN-02, GN-03 and GN-04. Experiments were carried out in three environments: Anhembi (SP) and Rio Verde (GO) in 1998/99 (normal season crop) and Piracicaba (SP) in 1999 (off-season crop). All experiments were in completely randomized blocks with six replications. Analysis of variance grouped over environments showed high significance for heterosis and its components, although mid-parent heterosis and average heterosis were of low expression. The interaction treatments x environments was not significant. Total mid-parent heterosis effects ranged from de -4.3% to 17.3% with an average heterosis of 3.37%. Population with the highest yield (7.4 t ha-1) and with the highest effect of population (v i = 0.746) was GN-03, while the highest yielding cross was GO-B x GN-03 with 7,567 t ha-1. The highest specific heterosis effect (s ii' = 0.547) was observed in the cross GO-B x GN-03.