The dynamic changes of cotton plant height, net photosynthetic rate, bud-shedting rate and root-shoot ratio in different growth stages of cotton under different fertilization treatments were studied in this paper, and the effects of different fertilization treatments on cotton yield parameters were analyzed. The results showed that the application of NPK fertilizer could accelerate the growth rate of cotton in a certain range (N≤360 kg/hm2, P≤180 kg/hm2 in this experiment), and the growth rate of N3P2 was higher than that of N0P2, N1P2 and N2P2, the amplifications were 18.49%, 12.61% and 3.07%, respectively. Increasing the application of potassium fertilizer could promote the growth of cotton in the later growth stage. During the whole growth period of cotton, the net photosynthetic rate (Pn) fluctuated. As the nitrogen level increased from N1 to N3, the net photosynthetic rate increased, but the effect of different application rates of phosphate fertilizer on cotton net photosynthetic rate (Pn) was not obvious. Compared with the control CK, fertilization significantly reduced the rate of buds and sheds of cotton, and significantly increased the effective number of bolls. The rate of buds in N3P2 treatment was 2.64%, 1.81% and 0.88% lower than that of N0P2, N1P2 and N2P2, respectively. The number of effective bolls increased by 3.0, 2.5, and 1.34/plant. The N2P3 treatment of cotton buds was reduced by 2.53%, 1.80% and 0.71%, respectively, and the effective number of bolls was increased by 2.0, 1.5 and 1.77/strain. Among them, N3P2 treatment had the highest number of effective bolls in all fertilization treatments, 8.67/strain, and N2P2K2 had the lowest rate of buds, which was 59.65%. The apparent utilization rate of nitrogen and phosphorus fertilizer, agronomic utilization efficiency, material contribution rate and yield increase benefit increased with the increase of nitrogen and phosphorus application. Through experiments, it was concluded that rational application of NPK fertilizer could effectively promote cotton growth, improve fertilizer utilization rate, and increase cotton yield, showing good economic benefits. |