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The Effect of Fertilization on the Absorption, Partition and Accumulation of Carbon and Nitrogen in Rice Plants

Author: FengLei
Tutor: ShiHui；TongChengLi
School: Xi'an University of Architecture and Technology
Course: Environmental Science
Keywords: rice accumulation of carbon and nitrogen distribution fertilization
CLC: S511
Type: Master's thesis
Year: 2011
Downloads: 165
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Abstract

Rice, the major crop for paddy field, whose growth is predominently controlled by the nitrogen （N）, and secondarily by the phosphorus （P） and potassium （K）. The plants form the carbohydrate almost from the photosynthesis which closes to the N input and N assimilation. Theoretically, it is important to link the carbon and nitrogen cycles. Here based on the long–term experiment in a typical paddy ecosystem, the carbon and nitrogen accumulation and allocation of rice organs was analysed under equal nitrogen input but different nitrogen sources and different NPK fertilization treatments. We aimed on the correlations of carbon and nitrogen accumulation of rice organs under various fertilization levels, which could shed light on the potential mechanisms of the coupling carbon and nitrogen cyclings in paddy field. The main results are as follows.（1） Based on the long–term experiment, with equal amounts but different sources of nitrogen inputs, in typical paddy ecosystems of subtropical region, the partitions and accumulation of carbon and nitrogen in rice were studied. The results shouwed that there were no obvious differences in carbon content of vary organs （root, stem–leaf, grain） between different fertilization regimes, but obvious one in nitrogen content. The nitrogen content of stem–leaf and grain under organic–inorganic fertilization was 8.9 10.2 g.kg^-1 and 11.9 14.8 g.kg^-1, respectively, and were 13%-53% and 9%-19% higher than those under chemical fertilization, and also 12%-77% and 23%-32% higher than those under non–fertilization, respectively. The most part of carbon and nitrogen storage of rice plant were in grain and stem–leaf. The organic–inorganic fertilization treatment exhibited the highest storages of carbon (3467.8 4323.9 kg.hm^-2) and nitrogen (120.3 135.2 kg.hm^-2) of grain, which was about 13% 23% and 26%⁴5% higher than those under chemical fertilization treatment, respectively. The carbon storage of stem–leaf and grain was 34%³8% and 51%⁶0% of that of the whole plant respectively, and the nitrogen storage of stem–leaf and grain was 28% ³4% and 61% ⁶8%, respectively. The results indicated that grain was the main sink of carbon and nitrogen of rice plant. The organic–inorganic fertilization favors the absorbtion and accumulation of carbon and nitrogen of rice plant, which improve the sequestration and accumulation of carbon and nitrogen of rice plant.（2） Based on a long-term field experiment established in 1990 in Taoyuan Experimental Station of Agriculture Ecosystem, Chinese Ecosystem Research Network （CERN）, the relationship of the accumulation and patition of carbon and nitrogen in rice plant and fertilizations with different levels of N, P, K input was analyzed. The results showed that the C content was higher in grains and stem-leafs than in roots. The N treatment showed the highest C content (432.79 g·kg^-1) in grains, whilst no significant difference was observed between other fertilization treatments. However, the N content of rice was significantly different between different fertilization treatments, with the highest value (18.9 g·kg^-1) under the N treatment, followed by the NPK treatment (17.93 g·kg^-1). Most of C and N storages of the rice plant was accumulated in the aboveground parts of grains and stem–leafs, which was 6.8⁹.2 times and 9.8¹4.1 times over that in the underground part, respectively. The C storage in the grains increased with the increasing level of N input. While under the same level of N inputs, the storages of C and N in grains were significantly lower under the N fertilizer than under the NPK fertilizer, and distinctly lower under the NC fertilizer than under the NPKC fertilizer. These results indicated that the mixing fertilization of N, P and K was more favorable in the accumulation and partition of C and N in rice plant, as compared with the N fertilization.（3） Two fertilization treatments with equal amounts of N input but different N source and different NPK level were conducted to study the distribution and accumulation of nitrogen and carbon in rice plants during the growth stage. The results showed that NPK fertilization significantly increased the nitrogen content of rice plant during the tillering and booting stage, compared with other fertilization treatments. During the booting stage, nitrogen content in roots and overground parts was significantly highest under the NPK fertilization in Ningxiang trial, with the value of 11.87g.kg^-1 and 20.06g.kg^-1, respectively. From heading to maturation, the organic–inorganic fertilization effectively promoted the accumulation and distribution of carbon and nitrogen of rice plant. The nitrogen of grains of late rice at maturity in Ningxiang trial were the highest under treatments of LOM and HOM, with the value of 20.36 g.kg^-1and 21.22 g.kg^-1 respectively.（4） The C-N ratio of grain at maturity was significantly lower under the organic-inorganic treatments than other treatments, of which the value was 28.0 and 35.0, respectively,and 84% of that under NPK treatment. Under different NPK levels （except for the CK treatment）, there was no significant difference of C-N ration of grains between different treatments; the C-N ration of stem-leaf was the highest （67.6） under the N treatment. During the growth stage of rice, organic-inorganic treatments reduced the C-N ratio. Generally, the C-N ratio were lower under the treatment with organic circulation （NPC and NPKC） than treatment without organic circulation （NP and NPKC）.In conclusion,the aboveground part of the rice plant was the main sink of carbon and nitrogen, especially the grains. The storages of carbon and nitrogen were increased by increasing the input levels of nitrogen. Under the equal input levels of nitrogen, NPK treatment was more conductive to the accumulation of carbon and nitrogen than N treatment. Under the equal input but different resource of nitrogen, the organic-inorganic treatment improved the nitrogen contents significantly in the rice plants. Under the different input levels of N, P and K, the contents and storages of carbon and nitrogen of the rice plants were higher under the treatment of organic circulation （NC, NPC and NPKC） than those without organic circulation （N, NP and NPKC）, which also promoted the assimilation and absorption of nitrogen and carbon in the whole growth stage of rice.This study indicated that rational fertilization can effectively promote the sequestration and accumulation of carbon and nitrogen of the rice plants. Organic-inorganic fertilization is beneficial to the absorption and accumulation of nitrogen in the rice plant, which still possess a certain potential in facilitating the fixation and accumulation of carbon and nitrogen in rice plant.

The Effect of Fertilization on the Absorption, Partition and Accumulation of Carbon and Nitrogen in Rice Plants

Abstract

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