Dry matters production after anthesis is very important for maize yield.To further clear its role in super high yield condition (high density with ample water and fertilizer supply),we compared yield components in three cultivated varieties,including Denghai661 (DH661),Zhongdan 909 (ZD909) and 970.According to the theory of yield performance,the post-anthesis yield performance parameters were analyzed.The changes of net photosynthetic rate,the contents of chlorophyll,soluble sugar,starch,total C and N were measured in the ear leaf.The results showed that there were significant differences in the yield among three varieties.Varieties with higher yield (DH661 and ZD909) had higher kernel weight per ear,while DH661 had more grains per ear (466.7) and ZD909 had higher 1000-kernel weight (392.7 g).The post-anthesis dry matter production and its partitive ratios in grains were both higher in the two varieties with higher yield.Yield performance analysis showed that the mean leaf area index (mLAI) and leaf area duration (LAD) were significantly and positively correlated with post-anthesis dry matter production and yield.The chlorophyll,total carbon and total nitrogen content decreased slowly and C/N ratio increased slowly in the two varieties with higher yield.The net photosynthetic rate (Pn) was relatively higher in the ear leaves in the whole grain filling stage.The photosynthate not only supplied to kernels but also stored as starch in leaves at the early phase of grain filling.Only when Pn declined at late phase of grain filling the accumulated starch began to degrade for the kernel filling.These results indicated that the balance between carbon and nitrogen metabolism,and slowing down the photosynthate decrease in ear leaf are responsible for maintaining higher mLAI and LAD,resulting in higher yield.%玉米高产实践表明增加花后干物质生产对于产量的进一步增加具有重要作用.为了探明高产条件下花后干物质生产增加的原因,本研究比较了玉米品种登海661 (DH661)、中单909 (ZD909)和970的产量差异,并利用产量性能分析理论剖析了花后的产量性能参数,分析了花后主要功能叶穗位叶的叶绿素含量、净光合速率和碳、氮含量的变化.结果表明,品种间的产量差异显著,产量较高的品种(DH661和ZD909)具有较高的穗粒重,而DH661具有较多的穗粒数(466.7),ZD909具有较高的粒重(392.7 g);产量较高的品种后期干物质生产及其向籽粒的分配比例高,产量性能分析表明花后的平均叶面积指数(mLAI)及光合势(LAD)与干物质生产及产量均呈显著正相关;产量较高的品种花后穗位叶叶绿素、全碳和全氮含量下降慢,碳氮比值增加慢,光合速率在整个灌浆期相对较高,光合产物不仅向籽粒运转,还能在叶片中以淀粉的形式持续积累,在后期随着光合速率的下降,淀粉才开始降解向籽粒运输.可见玉米花后碳氮代谢协调、光合作用和物质生产能力衰减缓慢对于有效维持较高平均叶面积指数和光合势,进一步提高作物产量具有重要意义.
展开▼
