Abstract :
Salinity is an important limiting factor of growth and yield of crops. Conversely, salicylic acid (SA) is known as a plant hormone for decreasing the adverse effects of salinity stress. Therefore, in the current study the effect of SA pre-treatment of seeds (at three levels of 0, 0.1 and 0.5 mmol) on germination and growth of seedlings of alfalfa was investigated under salinity stress conditions (at three levels of 0, 10 and 15 ds.m-1) in the laboratory of Jihad-e-Agriculture High Educational Complex, Scientific-Practical University of Kerman, Kerman, Iran as a factorial experiment based on a randomized complete block design with three replications. Salinity stress decreased germination percentage, seed vigor index and growth parameters (stem length, radicle length, and seedling fresh and dry weight). This decrease was stronger under 15 ds.m-1 salinity stress than the other salinity levels. On the other hand, SA pre-treatment improved growth and resulted in higher resistance of plants to salinity, so that it increased germination percentage, seed vigor index and growth parameters of the seedlings. Also, salinity intensified electrolyte leakage, while SA decreased it and this decrease was stronger at SA concentration of 0.5 mmol. It can be concluded that pre-treatment with SA induced adaptive responses in alfalfa plant under salinity stress and consequently, encouraged protective reactions in biotic membranes which improved the growth of alfalfa seedlings.
