秸秆还田与施氮对水稻根系分泌物及氮素利用的影响研究

Effects of straw returning and nitrogen fertilizer application on root secretion and nitrogen utilization of rice

秸秆还田及适宜的施氮水平,对于提高资源的利用效率及减少环境污染有着重要的意义,本研究以徐稻3号为材料,在盆栽条件下设置3种氮肥水平与2种秸秆处理,研究了秸秆与氮肥处理下水稻根际分泌特性的差异及其与养分吸收利用的关系。结果表明,在同一秸秆处理下,中氮(NN)增加结实期氮素的累积,提高氮(N)素的吸收利用率,同时,NN处理下根系分泌物中苹果酸、琥珀酸、有机酸总量、氨基酸的含量及根系活性上升。在同一氮肥处理下,秸秆还田提高N素吸收累积,增加根系分泌物中苹果酸、琥珀酸及草酸的含量,降低柠檬酸的含量,根系分泌物中有机酸总量、氨基酸含量及根系活性在秸秆还田后明显上升。相关分析表明,结实期根系分泌物中有机酸总量、苹果酸、琥珀酸、氨基酸的含量以及根系活性与氮素累积量及氮素吸收利用率呈显著或极显著的正相关。

More than half of the straw has been burnt or discarded for years in China, which is not only a waste of organic fertilizer but also pollutes the environment. Meanwhile, heavy use of nitrogen fertilizer has become a serious problem in rice production. The practice of returning straw to fields and of using nitrogen fertilizer has important significance for the utilization of resources to reduce environmental pollution. This study investigated the characteristics of root secretion and its relationship to nutrient absorption and utilization in different straw and nitrogen treatments. A mid-season japonica rice cuhivar （Xudao 6） was used as test plant with three ni- trogen levels （no nitrogen, normal nitrogen and high nitrogen） and straw treatments. N accumulation at grain filing and N recovery efficiency of NN treatment was significantly higher than that of the other treatments un- der the same straw conditions. Similar results were also observed in some other tested indexes, including ma- lic, succinic, total organic acid, amino acid and root activity. Under the same nitrogen treatment, N accumula- tion and utilization under straw returned at grain filing was higher than that in the other treatments. Straw re turning improved malic and succinic acid contents of tested rice cuhivars, but decreased the citric acid content. Root activity, contents of total organic acid and amino acid were also improved under the straw returning treat ment. The contents of total organic acid, malic, succinic and amino acid and root activity were significantly correlated with N accumulation at grain filing and N recovery efficiency. Possible reasons for the differences in fertilizer utilization and root secretion characteristics under different treatments are discussed.