| Nutrient release experiment of CRFs, field and pot experiments of tobacco were conducted to study nutrient release feature of CRFs, the characteristic of soil, agricultural characteristics of tobacco and mechanism to improving tobacco quality. The results were as follows:1. Nutrient accumulated release curve of CRFs showed an "s" shape, slow releasing, rapid releasing and decreasing releasing were three nutrient release stages of CRFs. Nitrogen release rate was the fastest of the three. Release rate of potassium was faster than that of phosphorus. Controlled-release fertilizers used in experiments benefited tobacco seedlings to take root and fed a large number of nutrients for flue-cured tobacco. What's more, CRFs increased nutrient utilization rate of fertilizers.2. CRFs significantly increased nitrogen and potassium content in leaves, but affected less on phosphorus content in leaves and nitrogen content in lower leaf. The analysis about accumulation ratio of dry matter and potassium content in tobacco leaves indicated that the important reasons of potassium content reduced in tobacco leaves were diluting effect of accumulation ratio of dry matter higher than that of potassium content. Compared to other treatments, SRCF increased potassium content in leaves at maturing stage. Nutrient release of CRFs was accordant with tobacco plant absorbing nutrient. Different fertilization level exhibited a significant effect on potassium content in tobacco leaves,the higher, the better.3. The correlation analysis indicated that tobacco breeding with higher potassium content possessed the characteristics of higher stalk height, wider stalk circumference, bigger leaf area, comparatively. The positive correlation was found between potassium content in leaves and stalk height, stalk circumference and leaf area. Dry matter accumulation reached significant at 5% level between CRFs and CCF treatments.4. Controlled-release fertilizers were concentrated in roots of tobacco plant, which...
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