玉米单交种性状整齐度好,杂种优势强,已在生产中被广泛应用。但是,单交种的增产作用只表现在第一代,第二代以后杂种优势显著下降。为了弄清单交种后代产量下降的原因,我们对单交种703的一、二、三代的植株和产量性状进行了对比观察,结果如下。 一、生长势及整齐度 观察表明,三叶期以后,单交种二、三代的幼苗生长势较一代显著减弱,特别是三代,约有50％的幼苗在生长过程中逐渐死亡,最终收获株数仅及一、二代的一半。 Maize single cross-species trait neat, heterosis, has been widely used in production. However, the increase of single cross breeding only in the first generation, the second generation after the hybrid advantage decreased significantly. In order to find out the reasons for the decline of yield of single crossbreds, we compared the yield and yield traits of the first, second and third generation of single crossbreed 703 with the following results. First, the growth potential and uniformity Observations show that after the three-leaf stage, single seed second and third generation seedling growth potential was significantly weaker than the previous generation, especially three generations, about 50% of the seedlings gradually died during growth, the final number of harvested Only one and two generations of half.