减施氮肥对棉花叶片光合特性、氮素含量及产量的影响OACSTPCD

[Purpose]This study was conducted to explore the effects of different nitrogen reduction measures on the photosynthetic characteristics,nitrogen content,and yield of cotton;providing a basis for nitrogen reduction and efficiency enhancement in the cot-ton region of the Yangtze River Basin.[Method]Using a random block design and'Ganmianza 1'as the test material,a total of four treatments were set up:no nitrogen application treatment(N0),conventional nitrogen application treatment(N1,nitrogen ap-plication rate of 345 kg·hm-2),nitrogen reduction treatment of 20%(N2,nitrogen application rate of 276 kg·hm-2),and nitro-gen reduction and organic fertilizer application treatment(N3,nitrogen application rate of 276 kg·hm-2,of which 10%nitrogen was applied in the form of organic fertilizer).The agronomic traits and leaf photosynthetic parameters,SPAD value,nitrogen con-tent,yield,and fiber quality of cotton were assessed under different nitrogen application treatments.[Result]N1,N2,and N3 treatments significantly improved cotton plant height,stem diameter,number of fruit branches,and total number of bolls per plant.Among them,N3 treatment showed a better promoting effect on cotton plant growth than N1 and N2 treatments.During the budding stage,the net photosynthetic rate(Pn)of functional leaves treated with N2 and N3 significantly increased by 16.12%and 17.49%,and intercellular carbon dioxide concentration(Ci)significantly increased by 33.49%and 35.42%,respectively,compared to those of the N0 treatment.During the flowering stage,N2 and N3 treatments significantly increased Pn by 28.27%and 34.74%,respective-ly,compared to N0.No significant differences were observed in SPAD value,nitrogen content,photosynthetic parameters,seed cot-ton yield,and fiber quality between N2 and N3 treatment functional leaves and that of N1 treatment.[Conclusion]On the basis of reducing nitrogen by 20%,applying organic fertilizer(urea equivalent to pure nitrogen 248.4 kg·hm-2,organic fertilizer equivalent to pure nitrogen 27.6 kg·hm-2)not only reduced fertilizer input but also ensured higher cotton yield,which is a suitable nitrogen application measure in the Ganbei cotton region of the Yangtze River Basin.