适量施氮增强盐胁迫下高羊茅生长和抗氧化能力

为土壤盐渍地区高羊茅(Festuca arundinacea)草坪的合理施肥,该研究用NaCl浓度为0,70,140mmol/L和不同NH4NO3水平(质量浓度为0.01,0.6,1.2g/L)对盆栽高羊茅植株进行交互处理,并测定处理后其生长量和抗氧化能力。结果表明,同一水平NH4NO3相比,NaCl胁迫下高羊茅鲜质量、干质量、含水率均低于无NaCl处理;而根系脱氢酶活性、硝酸还原酶(nitratereductase,NR)活性、超氧化物歧化酶(superoxidedismutase,SOD)同工酶活性NO3-含量、质膜透性和丙二醛(malonicdialdehyde,MDA)含量均强于或高于无NaCl处理;CAT(catalase,CAT)同工酶活性及蛋白表达量发生改变。同一浓度NaCl胁迫下,随NH4NO3水平增加,其鲜质量、干质量、含水率呈上升趋势;NO3-含量、质膜透性和MDA含量呈下降趋势;SOD同工酶增强;根系脱氢酶活性、NR活性、CAT同工酶活性和蛋白表达量增强幅度明显减弱。因此,与NH4NO30.01g/L相比,NH4NO30.6g/L改善了同浓度盐胁迫下高羊茅氮素营养、抗氧化能力和蛋白质表达量,增强了其耐盐性;而NH4NO31.2g/L能一定程度上改善其氮素营养,但根系主动吸收离子能力、清除H2O2能力和蛋白质表达量增强有限,引起根际环境NH4NO3积累,严重导致土壤次生盐渍化。该研究为盐渍土壤上的高羊茅草坪合理施用NH4NO3提供参考。

Appropriate nitrogen fertilizer strengthens growth and antioxidative ability of Festuca arundinacea under salt stress

Abstract: In order to fertilize properly for F. arundinacea cultivated in the soil salinity areas, an experiment was conducted to investigate the effect of NH4NO3 on growth and antioxidative ability of F. arundinaceawas under NaCl stress. F. arundinacea plants cultured with Hoagland nutrient solution (excluding nitrate nutration) in pots was treated with nine cross combinations of different NaCl concentrations at 0, 70, and 140 mmol/L, and three nitrate nitrogen levels at 0.01, 0.6, 1.2 g/L (the nine treatments were 0+0.01, 70+0.01, 140+0.01, 0+0.6,70+0.6, 140+0.6, 0+1.2, 70+1.2, 140+1.2) for 25 days, and then the fresh weight, dry weight, water content, root dehydrogenase activity, nitrate reductase activity, NO3- content, membrane permeability, and MDA content were determined, and SOD, CAT isoenzyme activity and protein expression were also studied by polyacrylamide gel electrophoresis (PAGE) or SDS-PAGE. The results show that, compared with the same level of NH4NO3, the fresh weight, dry weight, and water content of F. arundinacea under salt stress were lower than those of F. arundinacea without salt stress, while the changes of root dehydrogenase activity, nitrate reductase activity, NO3- content, membrane permeability, and MDA content were in the opposite. PAGE or SDS-PAGE showed that SOD isoenzyme activities increase as CAT isoenzyme activities or protein expression changed. Under NaCl stress of the same concentration, when NH4NO3 concentration increased, the fresh weight, dry weight, water content, and SOD isozymes activity also showed an ascendant trend, but NO3- content, membrane permeability, and MDA content decreased. Compared with NH4NO3 level 0.01 g/L, NH4NO3 0.6 g/L made root dehydrogenase activity, nitrate reductase activity, CAT isoenzyme activity, and protein expression amount increase markedly; and compared with NH4NO3 level 0.6 g/L, NH4NO3 1.2 g/L not only made the increment rate depression of root dehydrogenase activity, nitrate reductase activity, but also made CAT isoenzyme activity and protein expression amount have little change. Therefore, under the same concentration of NaCl stress, compared with NH4NO3 0.01 g/L leavel, NH4NO3 0.6 g/L treatment strengthened the absorption ability on water and inorganic ion of root and the ability of reduction NO3-, and so improved the nitrogen nutrition of F. arundinacea. NH4NO3 0.6 g/L treatment also raised the ability of antioxidation, especially it markedly raised the ability of scanvaging H2O2, and so reduced membrane lipid peroxidation and endocyte exosmosis. Moreover, NH4NO3 0.6 g/L treatment intensified the protein expression amount. All the changes contributed to the improved ability of the salt resistance of F. arundinacea. Under the same concentration of NaCl stress, compared with NH4NO3 0.6 g/L level, NH4NO3 1.2 g/L raised the ability of reduction NO3-; NH4NO3 1.2 g/L also improved the scanvaging superoxide anion, and so reduced membrane lipid peroxidation and endocyte exosmosis; while the ability of root absorption on water and inorganic ion, scanvaging H2O2, protein express were enhanced insignificantly. These changes made mitigative effect of osmotic stress and inhibition on growth decended, and which may lead to NH4NO3 accumulation in the rhizosphere environment, even probable soil secondary salinization if it was serious. This study provided reference for the reasonable application of NH4NO3 to F. arundinacea planted in saline soil.