氮素形态对作物生理特性及生长的影响

简要综述了近年来对不同氮素形态膜转运蛋白的研究概况。细胞膜上硝态氮和铵态氮均有高亲和和低亲和转运系统。目前已从多种作物中克隆了硝态氮低亲和系统的基因。根系吸收铵态氮，具有双动力学特征。研究表明，铵高亲和转运体应是AMTl家族的成员，此基因在酵母中得到了表达。还综述了氮素形态对作物生理特性影响的研究情况。作物在铵营养增加时，NR(nitrate reductase，NR)活较高；铵态氮营养条件下的GS活性更高。氮素形态对作物光合作用各环节等均产生明显影响。大多数研究认为，铵硝态氮混施，叶绿素含量高；增加铵态氮，希尔反应活性升高；氮素形态对光合速率的影响尚无定论。氮素形态对RuBPCase活性的影响因植物而异；硝态氮明显提高叶片的光呼吸速率。施用硝态氮，作物吸收的阳离子量明显增加，施用铵态氮，作物吸收较多的阴离子。氮素形态使作物体内呼吸途径改变，并可改变呼吸商。氮素形态对作物生长的影响，至今有不同的看法。

Effect of N Form on Crop Physiological Characteristics and Growth

Recent studies about the nitrogen transport systems and genes related were reviewed . There are low- and high-affinity transport syste ms (LATS and HATS, respectively) in the plasma membranes of root cells for uptak ing NO 3 - -N and NH 4+ -N. In higher plants, genes co nsidered to encode IHATS(inducible high-affinity transport systems for NO 3 -) have been cloned from barley,Arabidopsis,etc .Many studies showed that ammonium transport system had the biphasic kinetics in several species and members of the AMT1 family of transporters were responsible for high-affin ity ammonium transport system activity in plants. The first AMT1 gene discov ered in plants was AtAMT1;1 from Arabidopsis, which was cloned by compl ementation of a yeast (Saccharomyces cerevisiae) mutant defective in ammoniu m transport.The gene have now been expressed and studied in yeast.This paper sum marized the effect of nitrogen form on the physiological characteristics of crop . Increasing the proportion of ammonium, the activity of nitrate reductase was i ncreased too.N form had the remarkable effect on the every tache of photosynthes is including the content of cholorophyll, photosynthetic rate, activity of RuBPc ase, PEPcase and the photorespiration. Most research showed that the amount of c hlorophyll was higher under the mixed nitrogen nutrition; Increasing the ratio o f the ammonium, the activity of Hill reaction enhanced, but the effect of N form on the photosynthesis had the skimble-scamble conclusion. Influence of N form on the RuBPCase was variable according to the kinds of plant. Under the nitrate nutrients, the photorespiration of leaf was obviously higher .The content of cat ion in crop was higher with supplied the nitrate.The onions was higher with supp lied the ammonium. The N form could change the pathway of respiration. But, up t o now, there was no unitive conclusion about the effect of N form on the growth of crop.