冬樱花扦插苗与实生苗对不同形态无机氮素吸收的动力学特征分析

以冬樱花（Cerasus cerasoidesD. Don]Sok）扦插苗和实生苗为试材，研究其在水培条件下对外源铵态N（氮）和硝态N比例（5︰0、4︰1、3︰2、2︰3、1︰4）处理中铵态N、硝态N和总无机N素在24 h后的吸收动力学响应。结果表明：随着外源铵：硝比例的降低，铵态N的净流速逐渐下降，硝态N的净流速逐渐上升，扦插苗吸收的总无机N素净流速在外源铵︰硝比为3︰2时达到最大（6.70 ± 0.34）μmol ? h-1后下降，而实生苗在外源铵︰硝比为1︰4时达到最大（14.88 ± 1.99）μmol ? h-1；总体上，总无机N素进入扦插苗的平均净流速（4.76 ± 1.29）μmol ? h-1]低于实生苗（12.95 ± 1.35）μmol ? h-1]（P < 0.05），但两种苗木间净吸收速率差异不显著（32 ~ 34 μmol ? h-1 ? g-1）。养分吸收动力学参数拟合结果显示，扦插苗更加偏好于吸收硝态N，实生苗则更加偏好于吸收铵态N，但当外源铵硝比小于4︰1时，两种苗木同时偏向于对硝态N的吸收。控制外源铵硝比例在3︰2可以促进冬樱花扦插苗对无机N素的吸收，而控制外源铵硝比例在2︰3以下则更有利于实生苗对无机N素的吸收。

Kinetic Characteristics of Inorganic Nitrogen Uptake by Cerasus cerasoides Cuttings and Seedlings

Cuttings and seedlings of Cerasus cerasoidesD. Don]Sok were soaked for 24 h under hydroponic condition，where exogenous ammonium-nitrogen（N）and nitrate-N were supplied at concentration concentration-ratios of 5︰0，4︰1，3︰2，2︰3，and 1︰4. Thereafter，materials both seedlings and cuttings were sampled to detect their responses of N uptake kinetics. Results revealed that：with the decline of concentration concentration-ratio of ammonium to nitrate，net flux rate of ammonium-N decreased but that of nitrate-N increased，whilst net flux rate of total inorganic N for cuttings increased to be （6.70 ± 0.34）μmol ? h-1] until the concentration ratio of 3︰2，and that for seedlings increased to be （14.88 ± 1.99）μmol ? h-1] at the concentration ratio of 1︰4；Overall，net flux rate of total inorganic N incuttings（4.76 ± 1.29）μmol ? h-1]was lower than that in seedlings（12.95 ± 1.35）μmol ? h-1]（P < 0.05），but the difference of net uptake rate of N ions between cuttings and seedlings（32–34 μmol ? h-1 ? g-1）was not significant；Estimated parameters of nutrient uptake kinetics indicated that cuttings preferred the uptake of nitrate-N，but seedlings preferred the uptake of ammonium-N. However，when the concentration-ratio of ammonium to nitrate was lower than 4︰1 both propagation types preferred the uptake of nitrate-N. In conclusion，manipulations controlling the concentration ratio of ammonium to nitrate around 3︰2 could promote the uptake of inorganic N by cuttings，and the ratio of 2︰3 would benefit for the uptake of N by seedlings.