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作 者 ：曹云;范晓荣;孙淑斌;徐国华;沈其荣;狄廷君

期 刊 ：植物营养与肥料学报 2007年 13卷 1期 页码：99-105

关键词：增硝营养；水稻；硝酸还原酶；相对表达量；

Keywords:nitrate enhancement, Oryza sativa L., nitrate reductase, relative transcript level,

摘 要 ：利用控制条件下的溶液培养方法,研究了增硝营养(NH₄⁺∶NO₃^-比例为100∶0和50∶50)对两种不同的基因型水稻南光和云粳苗期生长和硝酸还原酶(NR)活性及基因表达量的影响。结果表明,不同基因型水稻在增NO₃^-营养下生物量、氮素含量、氮积累量的增幅南光大于云粳。NO₃^-的存在增强了水稻硝酸还原酶的活力和NR基因OsNia1、OsNia2的表达。不同基因在水稻幼苗中,两个品种OsNia2的相对表达量均高于OsNia1。就品种而言,无论叶片还是根系,增硝后南光OsNia2mRNA表达量都高于云粳;南光叶片OsNia1mRNA表达量也较云粳叶片高。增硝营养提高了水稻NR基因的表达,增加了NR活性,促进了水稻NO₃^-的同化利用,从而增加了氮素在植株地上部的积累同化。南光和云粳相比,前者对NO₃^-的响应更为强烈。

Abstract:Nitrogen is one of the most important nutrients limiting the production of cereal crops.There has been increased evidence that nitrate(NO₃^-) had an enhanced effect on rice production although it prefers ammonium(NH₄⁺) nutrition.Furthermore,rice is being increasingly cultivated in the soil intermittently irrigated or even in aerobic soil condition in China.Thus,nitrate plays a more remarkable role than ever before.Hydroponic experiments were carried out to study the effects of partial replacement of NH₄⁺ by NO₃^- on the growth,nitrogen(N) accumulation,nitrate concentration,nitrate reductase(NR) activity and expression patterns of two rice(Oryza sativa L.) NR genes,i.e.OsNia1,OsNia2 in two cultivars(Nanguang and Yunjing) at the seedling stage(35-day-old) under control conditions.The results obtained were as follows.Both rice cultivars growing in mixed N supply achieved a maximum biomass.NO₃^- supply could increase the biomass of rice shoots and roots on average by about 23% and 18%,respectively.Total N accumulation in Nanguang and Yunjing applying mixed N sources(NH₄⁺ and NO₃^-) was 18% and 8% higher than those single applying NH₄⁺.RT-PCR analysis of different samples revealed that transcript levels of OsNia1,OsNia2 increased in response to mixed N supply.The transcript level of OsNia2 was significantly higher than OsNia1 in both rice cultivars tested.Nanguang responses to NO₃^- in a greater way that the transcript levels of OsNia2 both in leaves and roots and OsNia1 transcripts in leaves were higher than Yunjing.NR activities of both in leaves and roots of Nanguang were more significantly promoted than Yunjing fed with NH₄NO₃.The high activity of NR [NO₂ 67 μmol/(g·h)] showed that rice was also efficient in absorbing and assimilating NO₃^-.The more efficient inorganic N assimilation resulted in an improved growth of rice.In conclusion,rice,like many plants,supplied with mixed N have a beneficial effect on crop growth NO₃^-.Therefore,promoting nitrification to a certain extent in paddy soil is of great significance for rice production.

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