亚低温与硝铵配比对番茄幼苗渗透调节物质及抗氧化酶活性的影响
Effects of sub-low temperature and nitrate to ammonium ratio on osmotic substances and activities of antioxidant enzymes in tomato seedling

【目的】探索亚低温及不同硝铵配比对番茄幼苗渗透调节物质及抗氧化酶活性的影响，为通过合理施肥调控番茄抵御亚低温危害提供参考。【方法】以番茄为材料，采用温室水培的方法，对比研究了常温(15～25 ℃)和亚低温（8～15 ℃）下营养液中NO3--N/NH4＋-N比例分别为100/0，75/25，50/50，25/75和0/100时对温室番茄幼苗抗寒性的影响。【结果】与常温条件相比，亚低温使番茄幼苗叶片O2-·产生速率、丙二醛（MDA）含量、脯氨酸含量、超氧化物歧化酶（SOD）活性升高；使番茄植株叶片可溶性蛋白含量和过氧化氢酶（CAT）、过氧化物酶（POD）活性降低。不论在亚低温还是在常温下，NO3--N/NH4＋-N比例为75/25时植株的抗寒性最强，此后随NH4＋-N比例的增大抗寒性减弱。【结论】亚低温条件下，NO3--N/NH4＋-N比例为75/25时最有利于提高番茄植株的抗寒性。
【Objective】This study explored the effects of sub-low temperature and nitrate to ammonium ratio on osmotic substances and activities of antioxidant enzymes in tomato seedling.【Method】With tomato plants in greenhouse as the material,the influence of NO3--N/NH4＋-N ratios (100/0,75/25,50/50,25/75,and 0/100) on the cold resistance in tomato was investigated by nutrient solution culture method under sub-low temperature in greenhouse.The plant under normal temperature was taken as control treatment.【Result】Sub-low temperature increased O2-· production rate,contents of malondialdehyde and proline,and activity of superoxide dismutase in leaves of tomato seedling,while decreased activities of catalase and peroxidase and content of soluble protein.Under both sub-low and normal temperature,the cold resistance of plants was the best when NO3--N/NH4＋-N ratio was 75/25,since when increase of NO3--N/NH4＋-N ratio in nutrition decreased cold resistance.【Conclusion】The NO3--N/NH4＋-N ratio of 75/25 was favorable to plant growth under sub-low temperature