NaCl对大麦硝态氮吸收动力学特征的影响

Kinetics characteristics of NO^(-)_(3) absorption of barley(Hordeum vulgare L.) pretreated with different concentrations of Na Cl and NO_3~--N

采用营养液培养方法研究了不同盐分和氮水平对大麦‘鉴四’(Hordeum vulgare L.)生长及硝态氮(NO3?-N)吸收动力学参数特征的影响。结果表明:不同浓度NO3?-N与Na Cl预处理后,大麦对NO3?吸收符合离子吸收动力学模型,其吸收动力学参数表现为NO3?预处理浓度增加后,Vmax增大,Km值增加,但增加的幅度不一致。对高亲和力系统来说,所有预处理大麦的NO3?-N吸收曲线均符合Michaelis-Menten方程的描述。1 mmol?L?1NO3?-N预处理中,120 mmol?L?1 Na Cl预处理比1 mmol?L?1 Na Cl预处理显著提高了NO3?-N的吸收速率;10 mmol?L?1NO3?-N预处理时,120 mmol?L?1 Na Cl预处理与1 mmol?L?1 Na Cl预处理无显著性差异。表明低氮环境下生长的大麦,其根系NO3?-N高亲和力系统受Na Cl影响较大。对低亲和力系统来说,所有预处理大麦的NO3?-N吸收曲线均符合Michaelis-Menten方程的描述。在1 mmol?L?1 NO3?-N预处理中,与1 mmol?L?1 Na Cl预处理相比,120 mmol?L?1 Na Cl胁迫的大麦NO3?-N吸收速率显著提高;10 mmol?L?1 NO3?-N预处理中,120 mmol?L?1 Na Cl与1 mmol?L?1 Na Cl处理相比,降低了大麦的NO3?-N吸收速率。表明低氮环境下生长的大麦,盐胁迫对其根系低亲和力系统有促进作用,而高氮环境下生长的大麦,盐胁迫对其低亲和力系统的NO3?-N吸收没提高作用。

To learn nitrogen absorption characteristics of plant under salt stress, the NO3·-N absorption ability of barley（Hordeum vulgare L.） cultivar ‘Jian 4＇ pretreated with Na Cl and NO3·-N were investigated using culture solution. The pretreatment concentrations of Na Cl were 1 mmol·L·1（CK） and 120 mmol·L·1, those of NO3·-N were 1 mmol（NO3·-N）·L·1 and 10 mmol（NO3·-N）·L·1. Barley growth and NO3·-N absorption were measured and the kinetics of NO3·-N absorption of highaffinity transport system and low-affinity transport system of barley were investigated. The results showed that the uptake of NO3·-N of barley pretreated with different concentrations of Na Cl and NO3·-N was in accordance with Michelis-Menten equation. Also the uptake kinetics parameters Vmax and Km were enhanced with increasing pretreatment concentration of NO3·-N. For high-affinity system, the uptake of NO3·-N of barley was in accordance with Michaelis-Menten equation for all the pretreatments. Under 1 mmol（NO3·-N）·L·1 pretreatment, compared with 1 mmol·L·1 Na Cl treatment, 120 mmol·L·1 Na Cl pretreatment significantly increased barley uptake rate of NO3·-N; while under 10 mmol（NO3·-N）·L·1, no significant difference in the rate of uptake of NO3·-N was observed between 1 mmol·L·1 Na Cl and 120 mmol·L·1 Na Cl treatments. This indicated that in low nitrogen environment, Na Cl restrained uptake of NO3·-N of high-affinity system. For low-affinity systems, the uptake rate of NO3·-N of barley was in accordance with Michaelis-Menten equation for all pretreatments. Under 1 mmol（NO3·-N）·L·1pretreatment, compared with 1 mmol·L·1 Na Cl treatment, 120 mmol·L·1 Na Cl treatment significantly increased the rate of uptake of NO3·-N. With 10 mmol·L·1 NO3·-N pretreatment, the uptake rate of NO3·-N under 120 mmol·L·1 Na Cl was lower than that of under 1 mmol·L·1 Na Cl pretreatment. This showed that under low nitrogen environment, salt stress improved root uptake of NO3·-N in low-affinity system. However, under high nitrogen environment, Na Cl stress did not alter obviously root uptake of NO3·-N in low-affinity systems.