Effects Of N,P,K On Nitrogen Loss From Rice Plant Tissue

The nitrogen absorption and losses under different nitrogen (N), phosphorus. (P), potassium (K) and illumination, temperature application on rice were investigated. The results showed that the losses of rice plants were ubiquitous. The tiptop N losses rates of rice plants reach 28.6%, otherwise, the lowest was 3.76% yet. The N loss ratios of rice plants were 8% to 20% under different illumination and temperature too. By analyze the correlation coefficients, we discovered the N loss ratios of rice plants were positive correlated with the levels of nitrogenous fertilizer markedly, but negative correlated with the levels of nitrogenous P and K contrarily. So it could be reduced the N losses of rice plants by decreased the N fertilizer due to lessen excessive accumulations on rice plants. Compounded suitability P and K fertilizer explicating on rice, the N losses would be decreased under medium N fertilizer. Addition to this, the weight dried was positive correlated with the N loss ratios of rice plants, otherwise, the latter was negative correlated with contents of N, N cumulation, total contents of N absorbed, and weight dried within leaves and total plants. Thus it could be reduced the N losses of rice plants by enhancing the growth of root of rice aimed to promote the hearty growth of root and plants.In this paper,15N differential method was adopted to study the influences of nitrogen rates on N loss from rice plant tissue, and the factors of affecting the N loss were analyzed. The N loss from rice tissue was studied by supplying different N rates (N 0,40,80 and 160 mg/L) for 10d under solution culture. Before the treatments, the N was fed with 15N (abundance 10%), and then the 15N was substituted by normal N during the 10d treatments. The results show that there are not significant changes in biomass for the 10d treatments with application of different N rates, which indicates that the absorbed N at the previous stage is available to maintain the growth of rice plant for a period of time. N contents of leaves and root are increased with the increase of N levels, while the 15N abundances of leaves and root are decreased noticeably with the increase of N levels, and the 15N abundance of leaves is noticeably higher than that of root. Obviously, N absorption by plants is increased in the high N treatment, and the absorbed 15N at early stage is diluted, which indicates N is transferring from root to leaves. N deficiency (N 0 mg/L) and over N supply (N 160 mg/L) both increase N loss from plant noticeably, and appropriate N supply (N 80 mg/L) increases N utilization noticeably. The growth stages of rice affect N loss rates remarkably. Under the condition of N 80 mg/L, N loss from plant is increased from 11.6% to 22.3% with the increase of rice growth period. Meanwhile, NH4+-N contents, and GOT activities are increased with the increase of N amount, and pH values of rice leaves are also increased. These results indicate that N use efficiency N is decreased due to the N loss from rice tissue, and ammonia volatilization may be one of the reasons for the N loss.15N differential method was adopted to study the effects of different nitrogen forms (NH4-N, NO3-N and NH4NO3) on N loss from rice plant tissue under the solution culture conditions, and the factors of affecting the N loss were analyzed. Firstly, rice seedlings were cultured in nutrient solution for two weeks and the N was fed with 15N (abundance 10%), and then transferred to the nutrient solution culture with different nitrogen forms for 10 d. The results showed that the rice with application NH4-N had the highest biomass than other nitrogen forms and the largest amount of N loss, the N loss rate of 17.06%. The rice supplied the complex nitrogen source (NH4NO3) had no significant differences in biomass with that of NH4-N, but the N loss rate decreased significantly, only 9.96%. There results indicated that the application of NH4NO3decreased N loss from the plant tissue, and improved the nitrogen utilization efficiency without affecting the rice growth conditions. In addition, Applied with NH4-N, NH3+ content, GOT activity and pH values in rice leaves were higher than other nitrogen forms, which indicated that ammonia volatilization resulted from the increase of NH3+ content in plant may be the main cause of the N loss from the plant tissue.15N differential method was adopted to study the influences of combining application of nitrogen, phosphorus and potassium on N loss from Oryza sativa plant tissue. The N loss from rice tissue was studied by supplying different NPK combinations for two weeks under solution culture. Before the treatments, the N was fed with 15N, then the 15N was substituted by different NPK combinations during two weeks. The results showed that there were not significant changes in biomass for the two weeks with combining application of N, P, K, but N contents of leaves and root were obviously different among the different NPK combinations trearments. N contents in leaves and root with N treatments were noticeably higher than the no N treatments, while 15N abundance was on the contrary. Results indicted that with N nutrition suppling the N absorption was increased and the absorbed 15N. at early, stage was diluted at the same time. Meanwhile, NH4+-N contents of leaves with N treatments were higher than that of no N treatments, which showed that the N level was related with NH4+-N contents. N loss rates of rice plant were between 15.18% and 34.35% under the combining application of N, P and K. Combining application of the arbitrary two of N, P and K could reduce the N loss rates of rice plant, increase the activity of GOT, and decrease the membrane permeability of leaves. The N loss rate and the membrane permeability was the lowest, and the activity of GOT was the highest in the normal nutrition treatment (NPK).