Laboratory of Plant Nutrition, Department of Agricultural Chemistry, Faculty of Agriculture, Nagoya University, Nagoya 464, Japan.
Plant Physiol. 1978 Oct;62(4):665-9. doi: 10.1104/pp.62.4.665.
The uptake of nitrate and ammonium by rice (Oryza sativa) seedlings was compared under various conditions. Nitrate uptake showed a 1-hour lag phase and then a rapid absorption phase, whereas ammonium uptake showed passive absorption during the first hour, then a shoulder of absorption, followed by a rapid metabolism-dependent absorption phase. Light did not affect the uptake of nitrate or ammonium. The uptake of nitrate and ammonium was markedly suppressed by removal of the endosperm. After removal of the endosperm, the uptake was restored by exogenous supply of 30 mm sucrose. No appreciable nitrate uptake was detected at temperatures below 15 C, whereas appreciable ammonium uptake occurred at 15 C, although lowered passive absorption and complete inhibition of the rapid metabolism-dependent absorption phase were observed at 5 C.Nitrate uptake was decreased by aeration and also by bubbling the mixture with O(2). It was greatly depressed by bubbling the mixture with N(2). These results suggest that there is a low optimal O(2) concentration for nitrate uptake. In contrast, ammonium uptake was increased by aeration, not influenced by bubbling with O(2), and slightly decreased by bubbling the mixture with N(2).Nitrate uptake was almost entirely inhibited by addition of cycloheximide, KCN, or arsenate. These compounds had scarcely any effect on the passive absorption of ammonium, but entirely depressed its successive metabolism-dependent absorption. Ammonium uptake occurred before nitrate uptake in solution containing both nitrate and ammonium.
在不同条件下比较了水稻（Oryza sativa）幼苗对硝酸盐和铵的吸收。硝酸盐吸收表现出 1 小时的滞后期，然后是快速吸收期，而铵吸收在最初的 1 小时内表现为被动吸收，然后是吸收肩部，接着是快速代谢依赖性吸收期。光照不影响硝酸盐或铵的吸收。胚乳去除明显抑制硝酸盐和铵的吸收。去除胚乳后，通过外源性供应 30 mM 蔗糖可恢复吸收。在 15°C 以下温度下检测不到明显的硝酸盐吸收，而在 15°C 时则发生明显的铵吸收，尽管在 5°C 时观察到被动吸收降低和快速代谢依赖性吸收期完全抑制。通气和用 O(2) 鼓泡混合物都会降低硝酸盐的吸收。用 N(2) 鼓泡混合物会大大抑制硝酸盐的吸收。这些结果表明硝酸盐吸收存在一个低的最佳 O(2)浓度。相比之下，通气会增加铵的吸收，用 O(2) 鼓泡混合物不会影响其吸收，用 N(2) 鼓泡混合物会略微降低其吸收。加入环己酰亚胺、KCN 或砷酸盐几乎完全抑制硝酸盐的吸收。这些化合物对铵的被动吸收几乎没有影响，但完全抑制了其连续的代谢依赖性吸收。在含有硝酸盐和铵的溶液中，铵的吸收先于硝酸盐的吸收。
