OPTIMAL ALLOCATION OF FIELD STRUCTURE IN FARMLAND ECOSYSTEM A CASE STUDY ON RELAY INTERCROPPING OF MAIZE AND WHEAT IN THE MIDDLE LIAOHE PLAIN
农田生态系统田间结构的优化配置——以辽河平原中部地区米麦间套作为例

By means of the commonly revised design of four factors and square regression, the relationships between crop yields of maize and wheat in relay intercropping and planting date of maize(X1),space between maize plants(X2), width of maize stand(X4) are studied in the middle Liaohe Plain in 1999 and 2000.The results as follows: both crop yield and the factors of field structures accord with square polynomial regressions. The effects of single factor construction on the total yields of maize and wheat are: width of maize stand, planting date, space between maize plants, degressively in turn. Following two groups of factors, planting date and space between maize plants, space between maize plants and width of maize stand, have significantly negative mutual effects on total yields of maize and wheat. The mutual effects on total yields are as follows: space between two plants and with width of maize stand, planting date of maize and width of wheat stand, planting date and space between plants of maize, degressively in turn. Optimal allocation of field structure in different yield levels in relay intercropping of maize and wheat could be confirmed by frequency analysis. The main problems are bring forward as well as the approaches to solve them, concerning the relay intercropping of maize and wheat in the studied region commonly existing at present.