樱桃番茄幼苗对硝酸盐胁迫的生长和生理响应

Growth and Physiological Responses of Cherry Tomato Seedlings under Nitrate Stress

以樱桃番茄(Lycopersicon esculentum Mill.var.cerasiforme Alef.)品种‘大红樱桃番茄’为材料,采用水培试验研究了外源施加0、50、100、150和200mmol·L-1硝酸盐(NO3-)对樱桃番茄幼苗生长和生理生化指标的影响。结果表明:硝酸盐处理6d后,番茄幼苗株高、鲜重、干重和相对含水量随着处理浓度的增加呈下降的趋势,而根冠比呈先增加后下降的趋势;番茄幼苗根系硫代巴比妥酸反应物(TBARS)、活性氧(ROS)、H2O2和蛋白羰基(PC)的含量均随着处理浓度的增加而增加;番茄幼苗根系SOD、POD、CAT和APX活性和基因表达均随着处理浓度的增加而降低,而其根系脯氨酸、可溶性糖和可溶性蛋白的含量随着处理浓度的增加而增加。研究发现,樱桃番茄幼苗生长在硝酸盐浓度为50mmol·L-1时受到影响不大,但硝酸盐浓度达到100mmol·L-1时已对番茄生长产生显著胁迫,导致膜脂氧化损伤,降低抗氧化酶(SOD、POD、CAT和APX)活性,但番茄也能够通过调节渗透调节剂的合成代谢来抵御硝酸盐胁迫,从而表现出一定的硝酸盐耐受性。

The effects of nitrate （NO3-） stress with 0,50,100,150,200 mmol. L-1 concentrations were studied on growth and physiological and biochemical indexes of cherry tomato （Lycopersicon esculentum Mill. var. cerasiforme Alef. ） variety ＇Dahong cherry tomato~ using the hydroponic culture test. The re- suits showed that the plant height,fresh weight,dry weight and relative water content decreased with the increasing of nitrate concentration after treated for 6 days,while the root to shoot ratio increased first and then decreased. The contents of TBARS, ROS, H202 and protein carbonyl （PC） of tomato seedlings increased with the increasing of nitrate concentration. The activities and gene expression of SOD,POD,CAT and APX of tomato seedlings decreased with the increasing of nitrate concentration. The contents of pro- line, soluble sugar and soluble protein of tomato seedlings increased with the increasing of nitrate concen- tration. Our experiment indicated that the 50 mmol · L-1 NO3- had little effect on the plants, while 100 mmol · L-1 NO3- inhibited the growth of tomato seedlings,caused damage to the membrane lipid and de- creased the activities of antioxidant enzymes （SOD,POD,CAT and APX）;However,the increased osmotic adjustment substance could adjust themselves to avoid nitrate stress,which led to some tolerant ability of tomato to nitrate stress.