| The differences between the canopy structure and photosynthetic characteristics of Xinluzao 10 and Xinluzao12, cotton varieties extended in north Xinjiang, were studied at different nitrogen rates and thus the fertilization at 600~900 kg nitrogen per hectare was obtained at the proper nitrogen rate. Comparatively, Xinluzao 10 was more sensitive to higher nitrogen rates than Xinluzao 12. And thus in cotton production, Xinluzao 10 would be adopted at higher nitrogen rates and Xinluzao 12 would be adopted at medium and high nitrogen rates. Increased leaf area indexes, decreased leaf obliquities, declined scattering and transmission coefficients of scattering and direct radiances, and elevated solar energy intercepting rates indicated that the responses to different fertilizer rates and the indexes of the optimal canopy structures of different varieties were the theoretical basis for increasing cotton yield. |