采用PVC管栽法对不同密度处理下玉米初生根系和各层次节根的生长发育及生理活性变化规律进行了研究。结果表明：随着玉米生长发育进程，各部位根系干物重、表面积及活性表面积的变化趋势基本相同，均呈单峰曲线变化；不同部位根系干物重、表面积及活性表面积达到峰值的时间和数值并不相同，表现为一个交替消长的过程，发生时间越晚、根层位越高，其峰值也越大，且高密处理的峰值均大于低密处理。根冠生长发育关系表明：在一定范围内玉米根系发生的层位及干重达到最大值的根系层位均能用叶龄来表述，且相关性达到了极显著。

With the PVC pipes planting experiments, study on changes of roots dry weight, surface area and activity area for maize from different densities. The results showed that changes current was a single apex of roots dry weight, surface area and activity area for maize from different densities at maize growth and development period. Because the start growth time of different parts of root system was different, so maximum and time were not identical, the dry weight, surface area and activity area were high at high layers root. The index was high density >low density. Further analyze the relation of growth and development of root cap showed that the relation of total numbers of root layers and numbers of dry max root layers can be used the leaf age to express at a certain area, and the relativity was very prominence.

北京市自然科学基金项目(4042015)、北京市科技新星项目(2003B14)