Utilization Potential of the Temperate Maize Inbreds Integrated with Tropical Germplasm

Abstract

A diallel mating experiment was conducted using ten maize lines, which consisted of five tropical, subtropical maize inbreds and five temperate maize inbreds developed by consecutive backcross and introducing tropical germplasm. Totally, ninety crosses were made based on Griffing method III. The objectives of this study were to evaluate: (1) combining ability of the ten lines; (2) heterosis and heterotic performance of these crosses between the temperate lines integrated with tropical germplasm and the same tropical lines. Ninety crosses were evaluated in Kunming, Yunnan province in 2008 and 2009. One local elite hybrid Yunrui 6 was used in the trials as a check. The results showed that the inbreds integrated with tropical germplasm YML598 and YML58 had highly significant GCA effects in most traits, which should have high use potential in maize hybrid breeding programs. And it was found that combining ability for grain yield was closely related to combining ability for most of yield component factors, yield per plant had positive correlation with most of traits except anthesis silking interval and round tip. And it was showed that most of hybrids with relative heterosis H ≥10% and highly significant SCA effects for yield per plant were the crosses between tropical subtropical lines and temperate lines, which suggested that the five tropical sub-tropical inbreds and five temperate inbreds still belonged to their previous heterotic group respectively, and their heterosis did not be changed. Thus, using tropical subtropical lines as donor, backcrossing consecutively with temperate lines may be an effective way to improve the latter.