Exogenous cyanide (CN⁻) effects on nitrogen (N) uptake, transport, and assimilation in rice seedlings were investigated at the biochemical and molecular levels. Seedlings were treated with either a 2-d or 4-d supply of potassium cyanide (KCN) in the nutrient solution containing nitrate (NO₃⁻) or ammonium (NH₄⁺). Although a KCN-induced increase was recorded in the activity of β-cyanoalanine synthase (β-CAS) in rice tissues of both NH₄⁺-fed and NO₃⁻-fed seedlings, the former showed a significantly greater assimilation rate for CN⁻ than the latter. The addition of KCN decreased NO₃⁻ uptake and assimilation, whereas a negligible impact was observed in NH₄⁺ treatments. Enzymatic assays showed a marked activities enhancement of glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH) in NH₄⁺-fed seedlings after KCN exposure. Similarly, the rises occurring in nitrate reductase (NR) and GDH activity in NO₃⁻-fed seedlings were also detected after 2-d exposure to KCN, whereas a significant reduction of GS and GOGAT activities was determined. The results suggest that although exogenous KCN at moderate or high concentrations caused repressively effects on biomass growth of both NH₄⁺-fed and NO₃⁻-fed rice seedlings, the nontoxic concentration of KCN supplied can serve as a supplemental N source in plant nutrition and N metabolism.

外源性氰化物（CN ^- ）对氮的影响（N）摄取，运输，和在水稻幼苗同化物在生物化学和分子水平的影响。（NO幼苗用氰化钾（KCN）的营养溶液含有硝酸一个2 d或4- d供给处理₃ ^- ）或铵（NH ₄ ⁺）。虽然KCN引起的增加是在水稻组织记录在β-氰合酶（β-CAS）的活性都NH ₄ ⁺喂食和NO ₃ ^-喂食的同种异体苗，前者表现为CN一个显著更大同化率^-比后者。加入KCN的NO减少₃ ^-吸收和同化作用，而在NH ₄ ⁺处理中观察到的影响可忽略不计。酶法测定表明，暴露于KCN后，NH ₄ ⁺喂养的幼苗中谷氨酰胺合成酶（GS），谷氨酸合成酶（GOGAT）和谷氨酸脱氢酶（GDH）的活性显着增强。同样，上升发生在硝酸还原酶（NR）和GDH活性在NO ₃ ^-后2-d暴露于KCN还检测喂食苗，而GS和GOGAT活性的显著减少了测定。结果表明，尽管中度或高浓度的外源性KCN均对NH ₄ ^+-饲喂和NO _3-的生物量生长产生抑制作用^。饲喂水稻幼苗，所提供的无毒浓度的KCN可以作为植物营养和氮代谢中的补充氮源。