Ammonium Effects on Nitrate Uptake by Roots of Upland and Paddy Rice Seedlings Related to Membrane Potential Differences  

作　　者：WANG Xiao-li WANG Yu-qian TAO Yue-yue FENG Ke 

机构地区：[1]College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225009, P.R. China

出　　处：《Agricultural Sciences in China》2010年第6期799-805,共7页中国农业科学（英文版）

基　　金：supported by the National Basic Research Program of China (the 973 Program, 2007CB109300)

摘　　要：Nitrate uptake characteristics and ammonium effects on nitrate uptake were compared between upland rice （Brazilian upland rice） and paddy rice （Wuyujing 3 and Yangdao 6） through the glass microelectrode technique and the concentration gradient method of uptake kinetics.Results indicated that nitrate uptake by rice seedlings and ammonium effects were depending on membrane potential of root cells.And upland rice and paddy rice presented obviously different responses.For all cultivars,the nitrate treatments induced rapid depolarization and then slow repolarization of membrane potential in root epidermal cells,and even hyperpolarization was observed when nitrate concentration was low.The membrane potential of epidermal cells in Brazilian upland rice roots was larger and its response to NO3- was bigger than those of two paddy rice cultivars.Depolarization of membrane potential was amplified when ammonium was simultaneously added with nitrate into the measure medium,but repolarization was reduced,even disappeared.Brazilian upland rice seedlings had high Vmax of nitrate uptake and low Km,furthermore,Vmax and Km were little affected by ammonium,but Vmax of Wuyujing 3 was reduced significantly.Therefore,inhibition of NH4＋ differed obviously between upland rice and paddy rice.Nitrate uptake characteristics and ammonium effects on nitrate uptake were compared between upland rice （Brazilian upland rice） and paddy rice （Wuyujing 3 and Yangdao 6） through the glass microelectrode technique and the concentration gradient method of uptake kinetics.Results indicated that nitrate uptake by rice seedlings and ammonium effects were depending on membrane potential of root cells.And upland rice and paddy rice presented obviously different responses.For all cultivars,the nitrate treatments induced rapid depolarization and then slow repolarization of membrane potential in root epidermal cells,and even hyperpolarization was observed when nitrate concentration was low.The membrane potential of epidermal cells in Brazilian upland rice roots was larger and its response to NO3- was bigger than those of two paddy rice cultivars.Depolarization of membrane potential was amplified when ammonium was simultaneously added with nitrate into the measure medium,but repolarization was reduced,even disappeared.Brazilian upland rice seedlings had high Vmax of nitrate uptake and low Km,furthermore,Vmax and Km were little affected by ammonium,but Vmax of Wuyujing 3 was reduced significantly.Therefore,inhibition of NH4＋ differed obviously between upland rice and paddy rice.

关 键 词：nitrate uptake membrane potential AMMONIUM upland rice paddy rice 

分 类 号：S63[农业科学—蔬菜学] TE626.86[农业科学—园艺学]