Effects Of Salt Stress On The Physiological And Biochemical Traits Of Seedlings Of Cherry Tomato

Salt injury is one of the prominent problem suffered in protected farming of cherry tomatoes. In order to provide salt-resistance breeding and salt damage prevention and control in protected farming of cherry tomatoes with theoretical basis and references, firstly the salt tolerance of cherry tomato cultivars at germination stage was studied and the two varieties that presented the most different salt resistance was screened; then the effects of salt stress of different concentration on growth traits and physiological and biochemical parameters of cherry tomatoes as well as the effects of salt stress of different time on salt resistance-related physiological and biochemical parameters were also studied,finally the effects of exogenous SA and ALA on salt resistance-related physiological and biochemical parameters of cherry tomato were examined. Its main results were as follows:1.It is easier to differentiate salt resistance of cherry tomato varieties under the NaCl concentration of 68 mmol/L~102 mmol/L during seed germination. Two varieties were tested by salt stress germination to have the most different salt resistances; the one with the strongest salt resistance was"Jingdan5"and the other that presented the weakest salt resistance was"Xiaoyuanzao".2.After the two varieties were stressed in 153-mmol/L NaCl treatment for 15 days,the difference of their root length appeared more significant. Under salt stress, the percentage of root dry weight of the variety with the strongest salt resistance increased more significantly than the one of the variety with the weakest salt resistance.3.After the two varieties were stressed under NaCl of 204 mmol/L for 10 days and 15 days, the seedlings of the variety with the weakest salt resistance presented a larger increase in relative electric conductivity than those of the variety with the strongest salt resistance; after they were placed under NaCl of 204 mmol/L for 15 days, the seedlings of the variety with the strongest salt resistance presented remarkably higher POD and CAT activities in their leaves than those of the variety with the weakest salt resistances. Therefore,15-day placement under 204-mmol/L NaCl could be adopted as the optimal conditions for biochemical and physiological testing of salt resistance of cherry tomato .3.After the two varieties were stressed under 51-mmol/L NaCl for 15 days,the difference of their EVAP and Ls appeared more significant。The decrease in Pn of cherry tomato mainly resulted from the stomatl limitation.5.Cherry tomato showed different sensitivities between seed germination and seedling stage . They were more sensitive to salt stressat the stage of seed germination than seedling stage .6.After cherry tmatoes were treated with salicylic acid and ALA, the seedlings of"Jingdan5"and"Xiaoyuanzao"got their salt resistances significantly enhanced. But ALA is better in increasing salt resistances of cherry tomatoes than SA.Salicylic acid is more useful to the cultivar of stronger salt resistance than the cultivar of weaker salt resistance.And SA presented better effect in increasing salt resistance of cherry tomato by its spraying at the concentration of 0.12 g/L. ALA presented favorable effect in increasing salt resistance of cherry tomato presented the stronger salt resistance by its spraying at the concentration of 12 g/100m2 and better effect in increasing salt resistance of cherry tomato presented weaker salt resistance at the concentration of 6 g/100m2 .Especially, better effect in increasing salt resistance of cherry tomato in the way of leaf spraying than the way of root pouring.