Effects of controlled release N fertilizer on photosynthetic characteristics and yield of cotton

The objective of this research was to study photosynthetic characteristics and yield of cotton under urea and controlled release urea fertilization. Lumianyan No.28 was grown under field conditions with three types of controlled release nitrogen fertilization, 100% PCU (pitch controlled urea), 50% PU (plain urea)+50% PCU (pitch controlled urea) and 100% CRBBF (controlled release bulk blending fertilizer). The results show that, compared with the CK2, the content of chlorophyll and the PSⅡ (Fv/Fo) activity, maximum photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP) and actual quantum efficiency (ФPSⅡ) at the leaf ages of 45 and 60 days are all increased under the 100% PCU and CRBBF treatments, and thus photosynthetic rate (Pn) of cotton leaf is increased. Compared with the CK2, the increased bolls per plant under the 100% PCU and CRBBF treatments are 0.77 and 0.84, and the seed cotton yields are increased by 6.2% and 5.0%, lint cotton yields are increased by 6.4% and 4.3% under the 100% PCU and CRBBF treatments. However, there are not obvious differences of photosynthetic characteristics and yield between the 50% PU + 50% PCU treatment and the CK2.