混合选择与改良S#-1家系选择对玉米群体的改良效果研究

 本研究完成了玉米群体中综3号（ZZ-3）C#-0的三轮混合选择和一轮改良S#-1选择。结果表明，两种方法对这个群体均有改良效果。经过三轮混合选择，依照两种不同的选择标准而分成的群体ZZ-3（M#-1）C#-3和ZZ-3（M#-2）C#-3比原始群体分别提高产量12.7%和11.4%，达到1%显著差异水平。经过一轮改良S#-1选择，所选标准有相应区别的群体ZZ-3（S#-1-1）C#-1和ZZ-3（S#-1-2）C#-1产量分别提高了8.5%和10.3%，也达到极显著水平。改良S#-1选择法的一轮选择效果相当于混合选择法的2-3轮。 对中综3号群体所选的目标性状，粒行数以16-20行之间为宜，过分加强粒行数的选择会影响改良群体的效果。 混合选择呈现出逐代累加的选择效果，在上述两种方法中，对产量进行选择，均伴随着穗长、每行粒数、穗粗、百粒重的增长。以粒行数而言，则没有多大变化，这可能是由于基础群体的平均粒行数19.15已达到相当高值的缘故。

EVALUATION OF MASS SELECTION VS. MODIFIED S_1 LINE RECURRENT SELECTION IN MAIZE POPULATION ZHONG ZONG NO. 3

Three cycles of mass selection and one cycle of modified S_1 recurrent selection have been completed in a maize (Zea mays L.) population ZhongZong No.3. The experimental results indicated that both the selection methods were equally effective in improving maize grain yield as well as ear related traits. The mean yield of the two populations designating ZZ-3 (M_1) C_3 for 3 cycles of mass selection and 2 ear row number criteria were increased 12.7% and 11.4% respectively over the original population yield. The increments of the improved populations ZZ-3 (MS_1-1) C_1 and ZZ-3 (MS_1- 2) C_1 through modified S_1 selection were 8.5% and 10.3%. The improvement effect attributed to one cycle modified S_1 selection were nearly equal to that of 2-3 cycles of mass selection.The present study also indicated that. as a criterion of selection, the 16-20 rows, seemed to be suitable in improving the yield level of the population Zhong Zong No.3,Along with the grain yield gains exerted by the two methods, we found concomitant increase in ear length, kernel number per row, ear diameter and 100-kernel weight, except the original population being averaged 19.15 was so high enough that further selection would be ineffective.Three growing seasons are usually required for completing one cycle of S_1 recurrent selection. In the case of method as practised in present study, only two growing seasons are needed. Additionally, this modified method has another advantage in reducing the genetic variance of the component families rapidly.