Effects Of Controlled-release Urea On Yield Of Summer Maize Under Different Soil Fertility

In this research, maize was cultured in field and pots, two types of controlled-release urea (CRU) CRU30, CRU60 with different nitrogen (N) release periods were the fertilizers tested. Two aspects were mainly researched: (1) Effects of CRU on yield and quality of summer maize; (2) Mechanisms of physiology and biochemistry for CRU affecting yield and quality were clarified from N absorption and utilization, photosynthetic property, physiological characteristics of root, characteristics of N metabolism, active oxygen metabolism and lipid peroxidation for summer maize. Main results obtained were as follows:1 Effects of CRU on yield of summer maize under different soil fertility Yield increase effect of CRU was significant in condition of single basal application with the same amount of N. In low fertility condition, the order of increasing yield of fertilizers was CRU30>CRU60>U (P<0.05). Compared with that of N0 (no N fertilization) and U treatment, the yield of CRU30 treatment increased by 49.62%, 22.05% respectively; In addition, the order was CRU60> CRU30>U (P<0.05) under high soil fertility, the yield of CRU60 application was 25.70%, 13.67% higher than that of N0, U treatment respectively. Dry matter accumulation and grain yield in high soil fertility were higher than those in low soil fertility, increasing yield effect were in order of low soil fertility>high soil fertility.The main reason for increasing yield in comparing with that of common urea in high and low fertility conditions was CRU adjusted the N supply to the N demand of maize, finally leading to high N recovery rate and N production efficiency; CRU applications reformed photosynthetic property, increased dry matter accumulation of summer maize and improved ear traits, the increase of...