Effect of Chemical Seed Priming on Seed Germination and Seedling Vigor of Tomato (Solanum lycoperscium l.) under Salinity Stress

Salinity is one of the most limiting factors in agriculture in many parts of the world. In this research, pre-treatment of tomato (Solanum lycoperscium l.) seeds using some inexpensive and suitable chemicals including calcium chloride, sodium chloride, potassium nitrate, chitosan, and menadion sodium bisulfite (MSB) at three salinity levels of 2.2, 4 and 8 dS/m in Randomized complete block design was done. Then the effects of salinity during seed germination stage and seedling growth of were investigated.  The results showed that under salinity treatments, 50 mM calcium chloride, 30 mM MSB, 0.6 and 0.4% w/v chitosan, total dry weight of stems and roots significantly increased to 37.51, 36.74, 35.68 and 27% respectively. On the other hand, increase in salinity levels showed a significant negative effect on shoot and root fresh and dry weights and drought tolerance indexes including drought tolerance, germination index, drought tolerance coefficient and mean of germination duration. Under salinity of 4 dS m-1, 41.48% and 83.46% decrease and under salinity of 8 dS/m, 84.28% and 96.38% decrease, in the fresh weight of stem and root compared to the salinity of 2.2 dS m-1 were observed respectively. Finally, the 50 mM calcium chloride showed the best results. These results might be related to the decrease of the time for endosperm induction, increase of embryo power in water uptake, change in content of sugar, organic components, and concentrated ions. These changes might cause an increase in germination speed and tolerance in unfavorable conditions.