【摘要】 这篇稿件分别描述1982年双流中稻的3×7、5×7及7×7寸~2密植生态系统。我们假定该系统为线性及非时变和小区的肥水条件一致,这就形成单输入、单输出并具有反馈的线性非时变生态系统。根据系统的方块图,求得主要环节及该系统的传递函数的一般公式,各密植系统的实际传递函数即因此产生。通过它们的稳定性判断及灵敏度分析,选出5×7寸~2系统。但这三种密植的亩产相差不大(最大之差为30斤)。各密植系统的光能利用率不高,不及1.5％。如提高光能利用率,可能得到大量干物质及高额产量,这必须找出干物质最多时的苗数及叶面积指数的最佳值。要保证足够的苗数及适当的叶面积,只有在肥料上下功夫,所以我们把选出5×7寸~2扩大面积试种,把原来每亩纯氮用量17斤改为26斤,终于得到比以前好的结果。更多还原

【Abstract】 The study has been finished on shuang liu farm of the Institute of Biology Chengdu, Academla Sinica.The present paper deals with the ecosystem on Density-Planting patterns for 3×7 5×7 7×7 square cun in median rice. We Assume the system to be linear, and time-invariant, and the same conditions in fertilizer and water. Therefore we get linear time-invariant ecosystem of feedback of single input and single output. The general formula of transfer function and, of each main loop is obtained by systematic block diagram. Furthermore the practical transfer function of density system is obtained. The system for 5×7 square cun is the best by stability discrimination and sensitivity analysis for each transfer function. But three density planting patterns is shown as a small difference in seed weight per mu (the most quantitative difference 30 jing) , and less the rate of utilization of the sunlight energy for each density system (under 1.5 per cent). However the most amount of dry material and ideal yield will be gained, if increasing the rate of utilization of the sun-light energy. Then it is necessary to found the best values of both the seedling number and the leaf area index respectively for getting the most amount of dry material. Perhaps the fertilizer can be controlled only as input factors for keeping enough seedling number and better leaf area. In order to examine the above points we chose the pattern in 5 × 7 square cun to be tested on the large area by fertilizer factors. The amount of pure nitrogen per mu is changed at 17 jing for 26 jing. The results are shown as the latter is better than the former.更多还原