控释尿素对水稻生理特性、氮肥利用率及土壤硝态氮含量的影响

为了探明控释尿素(CRU)提高氮肥利用率并减少土壤中硝态氮累积的作用机理,通过田间试验,研究了控释尿素对水稻氮代谢关键酶活性、氮肥利用率及土壤硝态氮含量的影响。结果表明,控释尿素能显著提高齐穗期和乳熟期叶片中的硝酸还原酶活性,特别是乳熟期最为明显;能显著增强水稻叶片谷氨酰胺合成酶和谷氨酰胺转化酶活性,且增强作用可持续到蜡熟期,其增强效果在齐穗期最为明显;还能显著提高乳熟期和蜡熟期叶片的蛋白水解酶活性。其中,以处理4(CRU60%+PU40%)最为明显。控释尿素还能显著增强籽粒中的谷氨酰胺合成酶和谷氨酰胺转化酶活性活性,并能显著提高水稻的产量及氮肥利用率,也是以处理4增强效果最为明显。控释尿素还明显增加了蛋白质的含量,在一定程度上改善了稻米品质。同时,控释尿素还可明显降低水稻土壤中硝态氮的含量,减少硝态氮向土壤深层渗漏数量,以减轻对地下水污染风险。

Effects of Controlled Release Urea on Physiological Characteristics and Nitrogen Use Efficiency of Rice and NO3--N Contents in Soil

Field experiments were conducted to study the effects of controlled release urea(CRU) on key enzymes activities of nitrogen metabolism of rice, nitrogen use efficiency and soil and NO₃^--N contents, in order to verify the mechanism of CRU on increasing nitrogen use efficiency and increasing soil NO₃^--N accumulation. The results showed that CRU could improve significantly nitrate reductase(NR) activities of rice leaves in full heading stage and milk stage, especially in milk stage. The activities of glutamine synthetase and glutamine transversase of rice leaves were obviously increased, and the enhancement continued till dough grain stage, especially in full heading stage. Meanwhile, CRU was able to promote significantly protease activity of rice leaves in milk stage and dough grain stage. The treatment of 4(CRU60%+PU40%) was the best treatment of the key enzymes activities of nitrogen metabolism. CRU also had better effect on promoting glutamine synthetase and glutamine transversase activities of brown rice, and increased significantly rice yield and nitrogen use efficiency, especially the treatment of 4. CRU enhanced significantly protein contents in brown rice, therefore which improved quality of rice to some extent. Moreover, CRU could reduce NO₃^--N accumulation in soil profile significantly. CRU application could evidently decrease the quantity of soil NO₃^--N leached to deep soil and lessen the risk to ground water pollution.