Abstract:

In order to explore the relation between heterosis and parents value, the general combing ability of parents, the specific combing ability of combinations and the genetic distance, using 10 male sterile lines (maintenance line) and 10 restorer lines were used to make 100 crosses by NCⅡ design to analyze heterosis of yield and agronomic characters and explore the method of predicting heterosis. The results showed: the over-parent and contrast heterosis of hybrids mainly presented panicle length, number of grains per panicle, filled grains per panicle. The ratio of possessing positive the over-parent heterosis combinations were 61.0%, 66.0% and 53.0% respectively, The ratio of possessing positive the contrast heterosis combinations were 62.0%, 78.0% and 79.0% respectively. There was stronger positive contrast heterosis for seed setting rate too. Heterosis were closely related with the value of female and male, mid-parent value, high parent value, low parent value, parents differentials. There significant correlation or very significant correlation between contrast heterosis and female parent value, average value of parents and high parent value. It was closely Correlation between heterosis and specific combining ability (SCA) and parents general combining ability (GCA). Especially, the contrast heterosis was significant positive correlation with SCA and parents GCA. Meanwhile, there was closely correlation between contrast heterosis and both differentials and sum of parents GCA. It was very complex in heterosis and genetic distance. The further parents genetic distance was, the stronger the heterosis was, as a genetic distance of 5-5.5 between two parents was.