Abstract: Comparative experiments of controlled drainage, conventional drainage and different nitrogen applications were conducted, and cotton growth indexes were measured. Path analysis was used to analyze the influencing factors of cotton yield. Results showed that the main factor was the number of the boll, followed by individual boll weight. No matter how much nitrogen was used, the number of the boll in both conventional drainage treatment and 80cm controlled drainage treatment (with controlled water level of 80cm underground) was larger than that in 30cm and 50cm controlled drainage, and was the largest in 80cm controlled drainage. The yield sorted by size was 80cm controlled drainage> conventional drainage> 30cm and 50cm controlled drainage. The effect of nitrogen application on yield was smaller than that of controlled drainage. Well-drained(80cm controlled drainage) but not overdrained treatment(conventional drainage treatment) could be more favorable to improve cotton yield.

Key words: growth indexes, path analysis, controlled drainage, nitrogen application, yield