| The experiment with different application rates of the controllable release fertilizer (i.e., coated compound fertilizer with polymer materials, CCF) was conducted in Ningxiang County in the early season and in farm fields in Hunan agricultural university (Changsha) in the late season in 2002. The tested varieties were Zaofan-5 in the early season and Xingxiangyou-80 in the late season. The nutrients content was 17% N, 7% P2O5 and 12% K2O in both CCF and uncoated compound fertilizers (UCF). The effects of CCF on the growth and development, the dry mater production and distribution, and some physiological characteristics of rice plants, and the nutrient content of both rice plants and soils were studied in this experiment. The main results were summarized as follows:1. The effect of CCF on rice tillering. According to the records of tiller growth, it can be seen from CCF treatments that tillers increased gently and the tiller peak appeared smooth at early growth phase. And higher ear-bearing tiller percentage at late growth phase was found in CCF treatment, of which treat C reached to 80.36% and increased by 5% compared with UCF treatment.2. The effect of CCF on dry matter production. More dry matter production was accelerated at early growth phase in UCF treatment but at medium and late growth phase in CCF one. As a result, the total dry matter accumulation in all CCF treatments was more than that in UCF treatment. At harvest stage, the dry matter accumulation of early rice in the treat 480 and 360 kg CCF/hm2 increased by 11.57% and 2.37% compared with the treat 600 kg/hm2 UCF respectively. As for late rice, the dry matter accumulation in treat C and D increased by 9.56% and 2.95% compared with UCF treatment respectively, of which treat C had the highest dry matter production.3. The effect of CCF on some physiology characteristics. CCF enhanced the leaf nitrate reductase activity of both early and late rice. For example, at maturity stage, the leaf nitrate reductase activity of early rice in treat 480 kg CCF/hm2 was 27.27% higher than that in treat 600 kg UCF /hm2, and the leaf nitrate reductase activity of late rice in treat C was 36.84% higher than that in UCF treatment. Meanwhile, CCFalso increased the leaf chlorophyll content, darkened the leaf color promoted the leaf photosynthesis during the medium and late growth periods. As the result of the enhancement of plant physiological activities, it is beneficial to set the base of high yielding of both early and late rice.4. The effect of CCF on the contents of N, P, K in "soil-plant" system. The results through studying the contents of N, P, K in "soil-plant" system at five key life stages showed: CCF increased obviously the contents and uptake rate of N, P, K of plants and effective nutrients in soils during the middle and late periods of rice. And higher nutrients (N, P, K) remained in soils was found in CCF treatments. Because CCF nutrients released slowly in soils and had longer action on plants, the losses of the fertilizer nutrients decreased, the use efficiency for rice in the current season was higher than that of UCF, of which the utilization ratio of N was as high as 69.29%, and higher than that of UCF by 22.22%; the ratio of P increased by 14.23%-15.91%; the ratio of K increased by 24.42-27.02%.5. The effect of CCF on yield agronomy properties of rice. Compared with UCF, CCF increase effective panicles, setting grains per panicle and setting grain percentage, of which the effective panicles increased by 4.5-13.95+104/ha, the setting grains increased 4.6-7.8 grains per panicle, the setting grain percentage was higher by 2.9%-3.5%. There was a little influence on 1000-grains weight. The improvement of economic characters resulted in the yield increase by 4.8%-11.4% of early rice and by 7.02%-11.94% of late rice. CCF also improved the ratio of grains to the straw and economic coefficient. These results indicated that CCF promoted the production of leaf photosynthesis and its distribution into the grains.6. The economic be...
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