The effect of NaCl stress on the germination of seed and growth of wild species and cultivated varieties of tomato
AbstractIn this study, a cultivated species (Lycopersicon esculentum 'Moneymaker') and a salt-tolerant wild species of tomato (Lycopersicon pimpinellifolium 'PI365967') were used to study growth characteristics within solutions of varying NaCl concentrations. Results show that the germination rates of PI365967 and Moneymaker were 100% under concentrations of 0 mmol/L NaCl. The germination of both types of plants delayed when treated with a 100 mmol/L NaCl conditional, but the germination rate of PI365967 was always significantly higher than Moneymaker. In the seedling growth period, the growth of roots and aerial parts of PI365967 and Moneymaker were inhibited under NaCl stress. However, the latter suffered a greater extent of inhibition than the former. Under a 200 mmol/L NaCl treatment, the growth of Moneymaker was strongly inhibited, and accompanied by chlorosis, but PI365967 maintained a good growth trend. Moreover, the degree of inhibition was small. Whilst gradually increasing the concentration of NaCl to 200 mmol/L, we found that the adaptation of the two types of tomato to salt stress increased (35 days after treatment). The plants of Moneymaker treated directly with concentrations of 200 mmol/L NaCl all died, but the plants treated with a gradual increase in NaCl concentration continued to grow at a slow rate. PI365967 had new lateral roots and buds grew as well. The results indicate that appropriate exercise of the salt stress can improve the salt-tolerance of tomato. It should be noted that PI365967 had greater capability of salt-tolerance.
Key words: Wild species and cultivated variety of tomato, germination of seed, growth of seedling, NaCl stress, salt-tolerant.