Ammonia exchange between rice leaf blades and the atmosphere: Effect of broadcast urea and changes in xylem sap and leaf apoplastic ammonium concentrations
Ammonia exchange between rice leaf blades and the atmosphere: Effect of broadcast urea and changes in xylem sap and leaf apoplastic ammonium concentrations
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DOI：
10.1111/j.1747-0765.2008.00299.x
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发表时间：
2008-10-01
影响因子：
2
通讯作者：
Nouchi, Isamu
中科院分区：
文献类型：
--
作者：
Hayashi, Kentaro;Hiradate, Syuntaro;Nouchi, Isamu
为了阐明撒播尿素对大气与水稻之间氨（NH3）交换的影响，我们研究了水稻叶片与大气之间的NH3交换通量、木质部汁液铵（NH4+）浓度、叶片质外体NH4+浓度和pH值，并确定了气孔NH3补偿点。使用实验盆在露天进行水稻（Oryza sativa L. cv. Nipponbare）栽培。准备无氮（NN）、标准氮（SN）和高氮（HN）3个处理，进行2次追肥。 NN、SN、HN处理在穗萌芽时分别喷施0、30、60 kg N ha(-1)尿素；NN、SN、HN处理在抽穗期分别喷施0、20、40 kg N ha(-1)尿素。使用动态室技术测量的水稻叶片和大气（SN处理）之间的NH3交换通量总体上显示出净沉积；然而，在抽穗期施用后1天，老叶发生净排放。相比之下，两次施用后1天，木质部汁液NH4+浓度显着增加，这表明NH4+从水稻根部直接运输到地上部分。这些应用没有导致叶片质外体 NH4+ 浓度的明显增加。尽管木质部汁液中的NH4+来自根部并且质外体中的NH4+可能受到NH3气孔沉积的影响，但木质部汁液中的NH4+浓度与叶质外体中的NH4+浓度之间的关系尚不确定。水稻气孔NH3补偿点估计为0.1-4.1 nmol mol(-1)空气(20℃)。根据温度校正的 NH3 补偿点解释的通过气孔的交换通量的方向和强度与观测到的水稻叶片和大气之间的交换通量一致。
To elucidate the effects of broadcast urea on ammonia (NH3) exchange between the atmosphere and rice, we investigated the NH3 exchange flux between rice leaf blades and the atmosphere, xylem sap ammonium (NH4+) concentration, leaf apoplastic NH4+ concentration and pH, and determined the stomatal NH3 compensation point. Paddy rice (Oryza sativa L. cv. Nipponbare) cultivation using experimental pots was conducted in the open air. Three treatments, no nitrogen (NN), standard nitrogen (SN) and high nitrogen (HN), were prepared for two supplemental fertilizations. Urea with 0, 30 and 60 kg N ha(-1) for the NN, SN and HN treatments, respectively, was broadcast at panicle initiation, and urea with 0, 20 and 40 kg N ha(-1) for the NN, SN and HN treatments, respectively, was broadcast at heading. The NH3 exchange fluxes between the rice leaf blades and the atmosphere (SN treatment) measured using a dynamic chamber technique showed net deposition in general; however, net emission from the old leaves occurred 1 day after the application at heading. In contrast, the xylem sap NH4+ concentrations increased markedly 1 day after both applications, which suggests direct transportation of NH4+ from the rice roots to the above-ground parts. The applications resulted in no obvious increase in the leaf apoplastic NH4+ concentrations. The relationship between the NH4+ concentration in the xylem sap and that in the leaf apoplast was uncertain, although the NH4+ in the xylem sap came from the roots and the NH4+ in the apoplast might be affected by the stomatal deposition of NH3. The stomatal NH3 compensation point of rice was estimated to be 0.1-4.1 nmol mol(-1) air (20 degrees C). The direction and intensity of the exchange flux through the stomata, interpreted on the basis of the temperature-corrected NH3 compensation point, agreed with the observed exchange flux between the rice leaf blades and the atmosphere.