摘要
由于淹水条件下土壤硝化作用被强烈抑制 ,人们对水稻氮素 (N)营养的研究主要侧重在铵(NH+ 4 )营养而忽略了对硝 (NO-3 )营养的研究。但值得注意的是 ,水稻根系能分泌氧气 (O2 ) ,这些O2 能被硝化微生物利用 ,从而将NH+ 4 氧化成NO-3 ,在根表形成的NO-3 立即被水稻吸收。但通常情况下从水稻土中采集的土样中较难测到NO-3 或数量极微。事实上 ,即便是完全淹水 ,水稻根系也是处于铵、硝混合营养中。本文首先论述了水稻根际通过硝化作用产生NO-3 的过程 ,然后从吸收速率和根系生物量两方面提出了NO-3 对水稻NH+ 4 吸收和同化的促进机理 ,并比较了NO-3 对侧根生长发育的局部刺激作用和系统抑制作用 ,其中对于NO3 -对侧根生长发育的局部刺激作用是由于NO3 -的营养作用 (NO-3 对植物体内糖类、氨基酸和内源激素的影响 )还是信号物质作用进行了详细阐述 ,最后提出了今后在水稻硝酸盐营养方面的研究方向。
Due to the inhibited nitrification in the bulk soil of lowland rice field, researches on nitrogen nutrition of rice mainly focus more on ammonium than nitrate. In fact, the roots of rice can excrete O_2 to surrounding soil and this can convert NH+_4 to NO-_3 in the process of nitrification at root surface or in rhizosphere. Rice roots are actually always exposed in a mixture of NH+_4 and NO-_3 although the predominant species of mineral nitrogen in the soil collected from the lowland rice field is ammonium. This paper reviews the nitrification process in the rhizosphere of rice,and discussed the stimulation of nitrate on the absorption and utilization of ammonium by rice from both the uptake rate and root growth. The pathways involved in the local and systemic responses to NO-_3 supply were also discussed. In terms of the local stimulation by NO-_3 on the lateral roots, the nutritional function and signal function of NO-_3 were clarified in details from its effect on carbohydrate, amino acid, phytohormones. Finally some issues on nitrate nutrition of rice are proposed to be studied further.
出处
《土壤学报》
CAS
CSCD
北大核心
2004年第5期803-809,共7页
Acta Pedologica Sinica
基金
国家自然科学基金项目 (3 0 3 90 0 80
3 0 2 70 790 )
