硝态氮对马蔺耐盐性及渗透调节物质的影响

 【目的】探讨施用硝态氮对马蔺(Iris lactea Pall. var. chinensis(Fisch.)Koidz.)耐盐性及叶片渗透调节物质的影响，为马蔺的栽培和管理提供理论依据。【方法】采用砂培马蔺幼苗，透灌含不同浓度NaCl和硝态氮的营养液(设置3个NaCl浓度0.1、140、210 mmol•L-1与3种硝态氮含量0.25、4和8 mmol•L-1交互组合的9个处理)，处理35 d后，测定叶片和根部的生物量、矿质元素吸收量以及叶片中主要渗透调节物质的含量。【结果】在中等盐浓度(140 mmol•L-1)处理下，施加多量硝态氮(8 mmol•L-1)更大程度地促进了马蔺叶片生物量的累积。当NaCl浓度增高到210 mmol•L-1时，4 mmol•L-1和8 mmol•L-1硝态氮处理区的叶片生物量相比对照增加了约30%，但两种浓度的效果没有显著差异(P＜0.05)。施加硝态氮降低了NaCl胁迫下马蔺的根冠比和叶片质膜透性,提高了叶片和根部的氮素含量，但没有显著改变无机离子(K+、Na+、Ca2+、Mg2+)的吸收量。硝态氮和NaCl交互组合处理下，叶片渗透调节物质中各无机离子的浓度大小为：Cl-＞K+＞Na+＞NO3-。硝态氮的施加显著降低了Cl-、Na+和K+浓度，但提高了脯氨酸和NO3-浓度。【结论】外施适量的硝态氮能显著提高马蔺的耐盐性，其机理与盐胁迫下氮营养的改善、脯氨酸和NO3-含量的增加以及根冠比、Cl-和Na+含量的降低等有关。

Influence of Nitrate Nitrogen on Salt Tolerance and Osmoticum of Chinese Iris

【Objective】The objective of this study was to investigate the salt tolerance of Chinese Iris (Iris lactea Pall. var. chinensis (Fisch.) Koidz.) and the osmoticum in leaves at different levels of exogenous nitrate, to provide a scientific basis for cultivation and management of Iris lactea. 【Method】 Seedlings in sand culture experiment were treated with nine cross combinations of different NaCl concentrations at 0.1, 140, and 210 mmol?L-1, and three nitrate nitrogen levels at 0.25, 4 and 8 mmol?L-1, respectively. After 35 d of treatment, biomass of leaf and root, uptake of mineral elements and the main osmoticum in leaves were determined.【Result】NO3- at 8 mmol?L-1 caused a much higher increase in leaf biomass than 4 mmol?L-1 nitrate at 140 mmol?L-1 NaCl treatment. The exogenous nitrate (4 and 8 mmol?L-1) caused a 30% increase in leaf biomass at 210 mmol?L-1 NaCl, compared to the values at 0.1 mmol?L-1. No differences in leaf biomass were observed between two nitrate concentrations (P＜0.05). Exogenous nitrate resulted in a decrease in root/shoot ratio and leaf membrane permeability but an increase in total N of leaf and root under NaCl stress, while it had no significant effect on mineral element contents (K+、Na+、Ca2+、Mg2+). Contents of inorganic ions in leaves under interactions of nitrate and NaCl was Cl-＞K+＞Na+＞NO3-. Increase in concentrations of exogenous nitrate caused a decrease in Cl-, Na+ and K+ contents but an increase in proline and NO3- contents.【Conclusion】The growth under NaCl stress was improved by exogenous medium concentration of nitrate, and the mechanism may depend on improvement of nutrient uptake under NaCl stress, increase in proline and NO3- and decrease in root/shoot ratio, Cl-, Na+ and K+ contents.