Effects of Controlled Release Fertilizer on Photosynthetic Characteristics, Yield and Quality and Use Efficiency of N and K of Tobacco

In order to provide the reference for research and development of high-quality, high-efficiency and environmentally harmless controlled release fertilizers for tobacco, the effects of controlled release fertilizer (CRF) and tobacco-specific compound fertilizer (TCF) on photosynthetic characteristics, yield, quality of flue-cured tobacco, and N and K use efficiency were investigated.The results showed that (1) when the nitrogen application rate increased from 90 to 150 kg/ha, yield and output value of flue-cured tobacco significantly increased, the ratio of first-grade tobacco leaves and average price slightly decreased.Total K content of all cured leaves increased or significantly increased.Nicotine content significantly increased, but contents of total sugar and reducing sugar significantly decreased.(2) Compared to TCF, CRF increased the chlorophyll content in tobacco leaves after vigorous growth stage of flue-cured tobacco and improved the photosynthetic rate, stomatal conductance and intercellular CO₂ concentration at vigorous growth stage.(3) Compared to TCF, CRF increased yield by 3%-8% and output value by 9%-16%, significantly increased contents of total K and nicotine, but significantly reduced contents of total sugar and reducing sugar.(4) CRF improved the use efficiency of N and K fertilizers.Under the N rate of 90 and 150 kg/ha, the N use efficiency increased by 21.1 and 8.7 percentage points, respectively.Under the K rate of 180 and 300 kg/ha, the K fertilizer use efficiency increased by 9.4 and 8.6 percentage points, respectively.In conclusion, CRF can improve photosynthetic characteristics at middle and late stages of flue-cured tobacco, increase yield and output value, improve quality of cured tobacco leaves and increase N and K use efficiency.