玉米氮效率的杂种优势分析

Analysis of Heterosis for Nitrogen Use Efficiency in Maize

在氮高效自交系筛选工作的基础上 ,利用NCⅡ设计进行了杂种优势分析 ,同时探讨了氮高效育种中亲本选配等问题。结果表明 :以农大 10 8在两个氮水平下的产量为对照 ,18个自交系组配的 72个杂交组合中 ,在高氮 (2 0 0kgN·hm-2 )条件下有 7个组合优势超过对照 10 % ,在低氮 (不施氮 )条件下有 5个组合优势超过对照 10 % ,而且氮高效杂交组合多数为中效×高效或高效×高效类型。两个氮水平下 ,氮效率性状F1代都表现近中亲遗传和超显性遗传共存的特点 ,而且具氮利用效率杂种优势的组合 (高低氮下均为 98 6 % )多于具吸收效率杂种优势的组合 (高低氮下分别为 6 8%和6 9 6 % )。若在低氮条件下进行氮高效育种 ,母本的遗传特性对F1代各性状影响较大 ,所以 ,应注重对母本氮效率性状的选择。吐丝期穗位叶叶绿素SPAD值与氮效率极显著相关 ,因而 ,可作为次级选择指标。

Based on selection of maize inbred lines with different nitrogen (N) use efficiency (NUE), the heterosis of NUE was analyzed and how to choose parents in the breeding for NUE was investigated by NCⅡ design. The results showed that, among the 72 crosses derived from 18 inbred lines, heterosis of seven crosses were 10% higher than that of the control hybrid ND108 at high N (200 kg·hm -2). At low N (no N added), heterosis of five crosses were 10% higher than that of ND108, most of high NUE hybrids were from the mid-efficient×high-efficient or high-efficient×high-efficient parents. Under both N levels, NUE were of characteristics with both mid-parent and over dominance heredity, and with both positive and negative heterosis. Most of the crosses showed positive heterosis, others showed positive partial dominance, no dominance, or negative partial dominance closed to mid-parent value. Few crosses were close to high or low parents. Heterosis percentage of N utilization efficiency was higher than that of N uptake efficiency. The characters of F 1 generation were influenced by female parent, therefore more attention should be paid in the breeding for N efficiency at low N. The chlorophyll content around the ear at silking stage (SPAD Value) was very significantly correlated with N efficiency at low N, so that it might be taken as one of the secondary selection indicators.