[Genetic effects on grain shape traits of indica black pericarp rice and their genetic correlations with main mineral element contents in grains].

Complete diallel crosses with 7 varieties of indica black pericarp rice were conducted to analyze the genetic effects on grain shape traits such as 100-grain weight, grain length, grain width and length/width and their genetic correlations with main mineral elements of Fe, Zn, Mn and P contents in kernels of parents and their F1s and F2s, by using the full genetic model including seed, cytoplasmic and maternal effects on quantitative traits of seeds in cereal crops. The results indicated that the grain shape traits were controlled by seed direct genetic effects, maternal genetic effects as well as by cytoplasmic effects. The seed direct genetic effects were more important than the maternal genetic effects for grain shape traits, and seed direct additive effects constituted a major part of their genetic effects. The narrow heritabilities of seed direct effects were high for 100-grain weight, grain width and grain length/grain width, while those of seed and maternal effects were intermediate for grain length. Therefore, more attention should be paid to the single seed selection on the 100-grain weight, grain width and grain length/grain width in early generations of hybrid offspring, while in the case of grain length, attention should be paid to single plant selection and single seed selection in late generations. The results also showed that there existed significant genetic correlations of seed direct additive, seed direct dominance, cytoplasm, maternal additive and maternal dominance between most of grain shape traits such as 100-grain weight, grain length, grain width, grain length/grain width and main mineral elements of Fe, Zn, Mn and P contents in grains. The improvement for nutrient quality traits of main mineral elements Fe, Zn, Mn and P contents in indica black pericarp rice could be realized by the indirect selection of grain shape traits in speciality rice quality breeding.