Effects of water-logging stress and nitrogen forms on nitrate reductase activity and glutamine synthetase activity of maize(Zea mays L.)plant at seedling stage | 淹涝胁迫和供氮形态对苗期玉米NR和GS活性的影响

Chinese. 采用砂培培养方法比较研究模拟淹涝胁迫和3种供氮形态NO3--N、NH4+-N和NO3--N与NH4+-N等体积混合(NO3--NH4+)对苗期玉米的生长、植株根系、茎鞘和叶硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性以及木质部伤流液和叶片硝态氮含量的影响。结果表明:根系是苗期玉米对淹涝胁迫最敏感的部位。在淹涝胁迫处理7 d后,整株生物量的抗淹涝胁迫系数从大到小依次为NH4+-N处理、NO3--N处理、NO3--NH4+处理。淹涝胁迫对NH4+-N处理的GS活性没有明显影响,但却导致NO3--N处理叶片的NR活性明显下降,降低幅度高达60%以上;同时,淹涝胁迫也造成NO3--N处理的木质部伤流液中的硝态氮的质量和叶片的硝态氮含量呈显著降低的趋势,说明在淹涝胁迫条件下,NO3--N处理自根系运输至地上部参与同化的硝态氮的量明显降低。结论:在本试验的模拟淹涝胁迫和供氮水平下,NH4+-N处理苗期玉米的NR和GS活性对淹涝胁迫的适应能力相对高于NO3--N和NO3--NH4+处理。

English. The effects of water-logging stress and nitrogen forms(ammonium,nitrate,the mixture of ammonium and nitrate at the ratio of 1:1)on growth,nitrate reductase(NR)activity,glutamine synthetase(GS)activity of different parts(leaf,stem and sheath,and root),and nitrate content in leaf and bleeding sap of maize plants at seedling stage were studied by using a sand culture experiment.The results showed that,water-logging stress inhibited the growth of maize plants under the mixture supply of nitrate and ammonium,and root was much more sensitive to water-logging stress environment.Since seven days under the stress condition led to the most reduction in the root fresh weight of maize plants supplied with the mixture of ammonium and nitrate,while significantly increased that of maize plants solely supplied with ammonium.Ammonium fed plants showed the highest biomass stress coefficient of total plants and the mixture of nitrogen forms fed plants showed the lowest.No inhibit effect was observed in the plants when ammonium was supplied as the sole nitrogen source,while nitrate was supplied as the sole nitrogen form,leaves NR activity under water-logging conditions was 60% lower than that of under non-stress condition supplied with the same nitrogen form.In contrast to nitrate supply,the GS activity of ammonium supplied plants was only slightly affected.Furthermore,significant reduction in the amount of nitrate nitrogen in bleeding sap and leaf nitrate content of nitrate fed plants was observed.Therefore,the present results revealed that nitrogen forms supply is a major factor affecting maize plants responses to water-logging stress,with the nitrogen metabolism of maize plants being more tolerant when ammonium was the solely nitrogen form used.