Studies on the Effect of Nonuniformity of Planting on Growth and Yield of Crops : II. Growth compensation and competition between hills in nonuniform rice population consisting of the hills of different number of seedlings

[摘要] Growth compensation between neighbouring hills consisting of different number of seedlings was studied in relation to degree of nonuniformity and planting density. According to the result obtained, the rate of growtht compensation increases with increase of density and degree of nonuniformity. Growth compensation is thought to be caused by interaction or competition between neighbouring hills or among individual plants. So, in order to express quantity of competition, competition index was tried. In this trial, total competition among individual plants is sum of competition within hill (intra-hill competition) and between neighbouring hills (inter-hill competition). The method of calculation of competition index is as follows. log+/+ = 1o9 7#+/77+1o9- +/Q/-here I(n) is dry weight of the isolated hill whose number of seedlings is n, P(n) is dry weight of the hill whose number of seedlings is n in population. According to this equation, competition index was calculated about populations which had different planting densities. The intra-hill competition index increases with increase of the number of seedlings of a hill. The inter-hill competition index increases with increase of plant density. In the distance between hills below 24 cm, inter-hill competition index exceeds intra-hill competition index. Reversely, in the distance between hills above 36 cm, intra-hill competition index exceeds inter-hill competition index. So, the converting point of intra- and inter-hill competition is in the distance between 24 cm and 36 cm.

[学科分类] 农业科学（综合）