Effects Of Vermiculite Priming On Seed Germination And Salt Tolerance Of Tomato Seedlings

Tomato(Solanum lycopersicum)is one of the most important vegetable crops in the world and also a model plant in plant genetics and solanaceae crops research were planted in both north and south China.Tomato is a moderate salt-stress crop.Seed germination and seedling stage are sensitive to salt stress.Whether seed can be healthy under salt stress is a prerequisite for plant growth and development.The priming seeds were prepared in the metabolic state of germination,and it can raise the seed vigor and enhance the resistance also save the amount of seeds,reduce production costs.Therefore,it is of great practical significance to study the physiological mechanism of seed and tomato salt stress.In this study,two tomato cultivars('Red Hezuo 909' and 'Pink Hezuo 906')were studied in the artificial climate chamber.The effects of vermiculite priming in salt stress on the amylase activity,germination index,photosynthetic pigments,antioxidant enzyme activities and osmotic substances in seed imbibition and seedling period were studied.The main results are as follows:1.This study investigated the responses of two tomato(Solanum lycopersicum)seeds('Red Hezuo 909' and 'Pink Hezuo 906')to the effect of seed germination potential,germination percentage,mean germination time and activity of antioxidant enzymes(SOD,POD,CAT and APX)in different concentration of KNO3,NaCl and different water content of vermiculite.The results show that primed seed with solid matrix with 70%content water after 5days get shortest germination time,highest germination potential,germination rate and the activity of antioxidant enzymet,and the effect was the best.2.In seed imbibition period,germination potential,germination rate and germination index were significantly increased,and mean germination time was decreased compared with seeds without vermiculite priming.Furthermore,the decline in the relative electrical conductivity and malondialdehyde content,the increase in the activity of a-amylase,antioxidant enzymes and more protein accumulation were detected during the seed germination period with priming under salt stress,but tendency of the soluble sugar content change of two primed tomato seeds were different under salt stress.The above results indicated that the solid matrix priming could enhance seed vigor and the ability of salt tolerance of tomato in seed imbibition period.3.In tomato seedling period,results showed that dry and fresh weights of stem and root were significantly increased,content of MDA was decreased compared with seedlings without vermiculite priming.Furthermore,the increase in the content of proline,chlorophyll and the activity of antioxidant enzymes and more osmotic substances accumulation were detected during the seedling growth period with priming under salt stress,and Chlb was stable than Chla,carotenoid was stable than Chl(a+b).The positive correlations among salt tolerance ability in different parts with the activities of antioxidant enzymes,osmotic substances were observed which suggested that the ability under stress tolerance associated with a decrease in seed lipid peroxidation to protect the stability of cell membrane structure and photosynthetic apparatus.