铵硝营养对水稻氮效率和矿质养分吸收的影响

Effects of NH_4^+ and NO_3~– on Nitrogen Efficiency and Mineral Nutrient Contents of Rice

NH_4^+和NO_3~–是对植物有效的两种主要无机氮源。水稻一般被认为是偏好NH_4^+的植物,但是在NO_3~–条件下,水稻也能良好地生长。大多数关于水稻铵硝营养的报道是在pH 6.0左右的水培条件下开展的,但是对于酸性条件下水稻铵硝营养研究很少。随着土壤酸化的加重及一些边际酸性土壤被用作水稻种植,研究酸性条件下水稻的铵硝营养具有重要意义。本文采用水培试验,在pH 5.0的条件下,通过添加和不添加pH缓冲剂MES(2-(N-吗啡啉)乙磺酸),研究了NH_4^+和NO_3~–对水稻生长、氮效率和矿质养分(N、P、K、Ca、Mg、Fe、Zn、Cu、Mn)吸收的影响。结果表明,在不添加MES的条件下,水稻地上部生长(株高、叶绿素含量、干重)在NH_4^+和NO_3~–之间没有显著差异,而添加MES后,NH_4^+处理的水稻地上部生长优于NO_3~–。不管是否添加MES,NO_3~–处理的水稻地下部生长(根长、根表面积和根物质量)优于NH_4^+。水稻含氮量和氮利用效率在不同NH_4^+和NO_3~–处理之间没有显著差异,但是NH_4^+处理的水稻氮吸收效率高于NO_3~–。与NO_3~–相比,NH_4^+增加了水稻地上部P和Fe含量,而降低了水稻地上部Ca、Mg、Zn、Cu和Mn含量,对K含量影响较小。上述结果表明,NH_4^+有利于改善水稻地上部生长,提高氮吸收效率、地上部P和Fe含量,而NO_3~–则有利于水稻发根,提高地上部Ca、Mg、Zn、Cu和Mn含量。

NH4^+ and NO3^- are two main inorganic N sources available for plant growth. Rice is generally considered preferable to NH4^+, but it also grows well under NO3^- condition. In the past, most reports on NH4^+ and NO3^- nutrition of rice were conducted under hydroponic conditions at about pH 6.0, but little research has been done on NH4^+ and NO3^- nutrition of rice under acidic conditions. With the aggravation of soil acidification and the use of some marginal acidic soils for rice cultivation, it is of great significance to study NH4^+ and NO3^- nutrition of rice under acidic conditions. In this paper, the effects of NH4^+ and NO3^- on the growth, N efficiency and mineral nutrient contents (N, P, K, Ca, Mg, Fe, Zn, Cu, and Mn) in rice were studied under hydroponics at pH 5.0 with or without pH buffer MES. The results showed that, although there was no significant difference in above-ground growth (plant height, chlorophyll content, and dry weight) between NH4^+ and NO3^- without adding MES, the above-ground growth of rice with NH4^+ was better than that with NO3^- when MES was added. Root growth (root length, root surface area, and root weight) of NO3^- treatment was superior to that of NH4^+ regardless of adding MES or not. There was no difference in N content and N use efficiency between NH4^+ and NO3^-. However, N uptake efficiency of rice with NH4^+ was higher than that of NO3^-. Compared with NO3^-, NH4^+ increased the contents of P and Fe, decreased the contents of Ca, Mg, Zn, Cu and Mn, and had little effect on K content in rice shoots. These results indicated that NH4^+ facilitates shoot growth, N uptake efficiency and P and Fe contents in rice shoots, while NO3^- is beneficial to improve rice root growth and Ca, Mg, Zn, Cu and Mn uptake by rice.