Effect of salicylic acid on germination and early growth of Securigera securidaca seedling under salinity stress

Lentil is a dicot, annual, and cross-pollinating plant that is found mainly in Fars, Khuzestan and East Azerbaijan provinces. The seeds of the plant are used in the treatment of cholesterol and blood sugar. Abiotic stresses such as salinity are important factors in reducing plant growth and yield. Although salinity can remarkably affect plant growth, its intensity depends on duration, type, plant species and growth stage. The greatest effect of salinity during the germination process is on germination rate and percentage and radicle and plumule length, as the increased concentration of ions in Therefore, studying of plant germination under salt stress and application of compounds such as salicylic acid to improve plant tolerance to salinity in saline areas can serve as a guideline for the cultivation of plants under such conditions. Therefore, this research aimed to study the effect of salicylic acid on the germination and growth parameters of Securigera securidaca L. under salinity conditions.

The experiment was conducted as a factorial in a completely randomized design with three replications under the germinator conditions in the laboratory of Fars Agricultural and Natural Resources Research and Education Center. Experimental treatments consisted of 5 levels of salinity stress (0, -0.3, -0.6, -0.9 and -1.2 MPa) and 3 levels of salicylic acid (0, 1 and 2 mM). The seeds were soaked in the treatments for 24h. At the end of the experiment (8 days), germination percentage and rate, seed vigor index, and fresh and dry weight of radicle and plumule were measured and calculated.

The results showed that all plant responses were affected by different osmotic potentials at p<0.01 compared with the control. The highest germination percentage was 91.11 under stress-free conditions and the application of salicylic acid at 1 mM. During the comparison of means for salicylic acid, the highest mean plumule length (10.88 mm) was related to 1 mM salicylic acid solution and the lowest (6.35 mm) was for control treatment, which showed an increase of 71.34%. Also, soaking seeds with salicylic acid caused an 84.98% increase in root fresh weight. An increase in salinity led to 96.30 and 94.62% decrease in radicle and plumule dry weights, respectively.

The study showed that soaking seeds with salicylic acid improved germination under salt stress conditions. Therefore, seed placement in salicylic acid solution (1 Mm) prior to cultivation can be used to improve the germination of Securigera securidaca L. under salinity conditions.

1- The most suitable concentration of salicylic acid for seeds soaking to increase plant tolerance to salinity stress is 1 mM.
2- Soaking of Securigera securidaca L. seeds in salicylic acid increases germination, seed vigor index and radicle and plumule length and weight under saline and non-saline conditions.