根施SA对番茄幼苗盐害损伤的修复效应

Remediation of Salt Damage to Tomato Seedlings from Root Application of Salicylic Acid

探讨根施水杨酸(SA)缓解番茄幼苗盐胁迫伤害的调节作用,为合理利用SA解决番茄栽培中的盐害问题和培育抗盐番茄品种提供科学依据。以"秦丰保冠"番茄品种幼苗为试材,在营养液栽培条件下,研究50-800μmol/L SA对100 mmol/L NaCl胁迫下番茄幼苗生长、叶绿素含量、气体交换参数、叶绿素荧光参数、膜脂过氧化及抗氧化酶活性的影响。结果显示,盐胁迫下,不同浓度SA处理的番茄幼苗生长抑制均能得到有效缓解,同时叶片叶绿素含量、光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、最大荧光(Fm)、PSⅡ最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)和光化学淬灭系数(qP)不同程度升高,细胞间隙CO2浓度(Ci)、最小荧光(Fo)和非光化学淬灭系数(NPQ)显著降低,其中SA浓度为200μmol/L时,各指标变幅均达到最大;在盐胁迫下,番茄幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、丙二醛含量和电解质渗出率显著升高,过氧化氢酶(CAT)活性变化不显著,施加各浓度外源SA处理促进了上述3种酶活性的升高,同时使叶片丙二醛含量和电解质渗出率显著降低,并以200μmol/L SA处理时变化最显著。外源SA主要通过增强幼苗叶片的光合能力来缓解盐胁迫造成的氧化伤害,进而提高番茄植株的耐盐性。本试验条件下,以200μmol/L SA处理效果最好。

This work is to explore the regulation effect of root application of salicylic acid(SA)eliminating salt stress damage to tomato seedlings,and to provide scientific basis for rational use of SA to solve salt damage in tomato cultivation and breeding salt-tolerant tomato varieties.Under the condition of nutrient solution cultivation,a hydroponic experiment was conducted to explore the effects of different concentrations(50,100,200,400,and 800μmol/L)exogenous SA on plant growth,chlorophyll content,gas exchange,chlorophyll fluorescence parameters,membrane peroxidation,and antioxidase activity in tomato cultivar(‘Qinfeng Baoguan’)seedlings under stress of 100 mmol/L NaCl.The results showed that the growth inhibition of tomato seedlings under salt stress was effectively alleviated after treated with different concentrations of SA.Meanwhile,the chlorophyll content,net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),maximum fluorescence of leaves(Fm),PSII maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII),and photochemical quenching coefficient(qP)increased to varying degrees,while intercellular CO2 concentration(Ci),minimum fluorescence Fo and non-photochemistry quenching coefficient(NPQ)significantly decreased.The amplitude of each index reached the maximum especially when the concentration of SA was 200μmol/L.When tomato seedlings were put under salt stress,the superoxide dismutase(SOD),peroxidase(POD)activity,malondialdehyde content,and electrolyte exudation rate of theirs leaves raised remarkably,while their catalase(CAT)activity did not change so obviously.Application of exogenous SA treatment at various concentrations promoted the increase of the three enzyme activities above,along with making the leaf malondialdehyde content and electrolyte exudation rate markedly reduced;moreover,the change was the most significant when treated with 200μmol/L SA.Studies have demonstrated that exogenous SA could relieve the oxidative damage caused by salt stress mainly by enhancing the photosynthetic capacity of seedling leaves,hence improving the salt tolerance of tomato plants.The treatment with 200μmol/L SA showed the best results under the experimental conditions,.