Study On Salt-Tolerance Of Tomato (Lycopersicum Esculentum Mill.) At Germination And Seedling Stages

In order to establish an easy way to identify the salt tolerance and provide the theoretical basis for salt tolerant breeding and the mechanism study of tomato. The effects of NaCl stress on the germination and seedling of 8 tomato varieties were studied.The concentrations of NaCl as Ommol-L(CK), 40mmol-L-1, 60mmol-L-1, SOmrnol-L-1 and 100 mmol-L-1 were used.The main indicators of germination stage were germination percentage, germination energy,germination mdex,radicle length and cotyl length,and SOD activity,POD activity, MDA content,soluble protein content and ratio of root to shoot were measured at seedling stage by hydroponics method.Salt tolerance ability among different varieties and the correlations of salt tolerance indexes in two periods were compared and investigated.The main results were as follows:1.The effects of NaCl on germination stage of tomato showed that: The hypo cotyl length of 8 tomato varieties were higher than the control under the 20mmol-L-1salt stress,which indicated that the low concentration of salt stress had some roles in promoting the growth of tomato hypocotyls.The inhibitory effect on all varieties was relatively small as the concentration of NaCl at 20-40 mmol-L-1The mhibitive effect on seed germination grew with the increasing of NaCl concertration,when the concentration of NaCl was oOrnrnol-L-1 the germination percentage,germination energy,germination index,radicle length and hypocotyl length of all varieties were significantly decreased.Considering the change of various indicators at germination stage in different salt concentrations,the appropriate concentration of NaCl to identify the salt tolerance ability at germination stage of tomato was oOmmol-L-1.2.The effects of NaCl on seedling stage of tomato showed that:with the increasing concentration of NaCl stress,the indicators with an rising trend included POD activity.soluble protein and MDA content, where as,the SOD activity,shoot fresh weight and root fresh weight showed a downward trend. The seedling of Fl grew well and the MDA content in its leaves was the least among the 8 materials under salt stress.3.Correlations of indexes at the two stages:in all treatments,there were significant or very significant correlations between germination energy and germination index,the shoot fresh weight and root fresh weight,negative correlations between germination percentage and MDA content,germination percentage and ratio of root to shoot,germmation energy and POD activity,gerrnmation energy and MDA content,germination index and POD activity, germination index and MDA content;positive correlations between germination energy and SOD activity,germination energy and soluble protein content,germination index and soluble protein content,gerrnination index and the shoot fresh weight,gerrnination index and root fresh weight.4.Considering the seeding growth of different tomato varieties and the performance of indicators at germination and seedling stage,the germination energy and MDA content could be used as the indicators of salt tolerance at germination and seedling stage.respectively.Fl was with the strongest salt tolerance among the 8 tomato varieties.