Genetic background effects of F1 and F2 generations for ear-kernel characters and suitable population selection in corn | 玉米F1、F2代穗粒性状的遗传效应分析和适宜群体筛选

Chinese. 利用2个优良爆裂玉米自交系与6个Reid类群普通玉米自交系杂交组配12个杂交组合，研究穗长、穗粗、穗行数、行粒数、百粒重、穗重、穗粒重和出籽率8个穗粒性状的F，表现、杂种优势和F2群体表现、分离特征及其与亲本的相关性。结果表明，不同组合F1表现、中亲优势（MH）、超高亲优势（HH）和F2群体的平均值（F2M）、变幅、变异系数、优势衰退（HDR）等均存在不同程度差异，各穗粒性状杂交早代的遗传背景效应突出；F2群体各性状均呈连续正态分布，存在超双亲分离，为多基因控制的复杂数量性状；杂种优势较小的穗行数、出籽率和穗粗可以根据两类亲本或其均值初步预测其组合F1和F2M值的表现，对于杂种优势较大的穗重、穗粒重和百粒重不宜进行预测；除穗行数和出籽率外，其余性状F1表现与F2M、MH和HH以及F2M、MH、HH间多呈显著或极显著正相关，HDR与F1、F2M、MH和HH均呈显著或极显著负相关；R2×N04、R4×N10和R5×N10组合为进一步开展遗传作图和改良爆裂玉米自交系穗粒性状的最佳群体。

English. Using two popcorn inbred lines and six normal corn inbred lines belonging to Reid heterotic group, twelve F1 crosses and their F2 populations were developed. The F1 performance, heterosis, F2 performance and segregation characteristics, and their correlations with parent lines were analyzed for eight earkernel characters, including ear length, ear diameter, ear row number, kernel number per row, 100 grain weight, ear weight, ear grain weight and kernel rate. The results showed that great differences existed among crosses in F1 performance, mid-parent heterosis (MH) and over-high parent heterosis (HH), and mean value F2M, range, variation coefficient and hetrosis decreasing rate (HDR) in F2 populations, reflecting obvious genetic background effects. All traits showed normal distributions in F2 populations, with transgress segregations beyond two parents. For traits with low heterosis, such as ear row number, kernel rate and ear diameter, F1 performance and kernel rate could be predicted according to parent values, while it was unsuitable for traits with high heterosis, such as ear weight, ear grain weight and 100 grain weight. Besides ear row number and kernel rate, significant positive correlations were observed between F1 with FEM, MH and HH, and among F2M, MH and HH. However, they were all negatively correlated with HDR. Three crosses, R2 × N04, R4 × N10 and R5 × N10, were chosen as much better crosses both in genetic mapping and in improvement for earkernel characters in popcorn breeding.