外源亚精胺对Ca(NO3)2胁迫下番茄幼苗光合特性和抗氧化酶活性的影响

以耐盐性较弱的番茄品种上海‘合作903’幼苗为试验材料,采用营养液栽培方法,研究了叶面喷施1mmol.L-1亚精胺(Spd)对75mmol.L-1 Ca(NO32)胁迫下番茄幼苗生长、叶绿素含量、光合及荧光参数、叶片抗氧化酶活性的影响,以探讨外源亚精胺缓解Ca(NO3)2胁迫伤害的机制。结果显示:Ca(NO3)2胁迫能够显著抑制番茄幼苗的生长;与Ca(NO32)胁迫处理相比,叶面喷施外源Spd 9d后,受胁迫番茄幼苗的株高、茎粗、干重、鲜重分别显著增加70.9%、15.8%、43.4%、41.4%;叶绿素a、b的含量分别提高17.7%、13.8%;净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、光合电子传递效率(rETR)和光化学猝灭系数(qP)分别升高6.6%、18.0%、31.0%、4.9%、5.0%,而胞间二氧化碳浓度(Ci)、非光化学猝灭系数(qN)分别降低21.5%、8.1%;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性分别增加10.7%和37.5%,而丙二醛(MDA)含量和超氧阴离子(O2.-)产生速率分别显著下降34.5%、17.1%。研究表明,外源Spd通过提高番茄幼苗抗氧化酶活性来有效清除体内活性氧,维持光合机构的稳定性,提高其光合速率,从而缓解Ca(NO3)2胁迫对番茄幼苗的伤害。

Effects of Exogenous Spermidine on Photosynthesis and Activities of Antioxidant Enzymes in Tomato Seedlings under Ca(NO3)2 Stress

With tomato variety shanghai ’Hezuo 903’ as material,we investigated the effects of exogenous spermidine(Spd,1mmol·L-1) on plant growth,chlorophyll fluorescence and photosynthetic characteristics,and active oxygen metabolism in tomato seedlings under 75 mmol·L-1 Ca(NO3)2 stress by hydroponic culture,and studied the mechanism of how exogenous spermidine ease the Ca(NO3)2 stress.The results showed that Ca(NO3)2 stress can significantly reduce plant growth.However,in the treatment of Spd for 9 d under Ca(NO3)2 stress,the seedlings height,stem diameter,the fresh and dry weight were significantly increased by 70.9%,15.8%,43.4%,41.4%,respectively.The chlorophyll a content,chlorophyll b content,Pn,Gs,Tr,rETR,qP were increased by 6.6%,18.0%,31.0%,4.9%,5.0%,respectively,while Ci,qN were decreased by 21.5% and 8.1%,respectively.The activities of SOD and CAT in leaves were significantly enhanced by 10.7% and 37.5%,respectively,while the accumulation of malondialdehyde(MDA) and O-·2 producing rate were significantly decreased by 34.5%,17.1%,respectively.These results showed that exogenous Spd can effectively remove reactive oxygen species by increasing the activities of antioxidant enzymes in tomato seedlings,maintain the stability of the photosynthetic apparatus,increase their photosynthetic rate,and thus ease the Ca(NO3)2 stress on tomato seedling damage.