Study the Effects of Salicylic Acid and Glycine Betaine on Qualitative Traits of Alfalfa (Medicago sativa L.) under Drought Stress Conditions

The utilization of substances like salicylic acid and glycine betaine has proven to be beneficial in enhancing plant tolerance to environmental stresses, particularly drought. These compounds act as antioxidants, playing a vital role in diminishing the generation of reactive oxygen species (ROS), enhancing the efficiency of chloroplasts and promoting the synthesis of protective compounds such as proline.
Investigate the use of salicylic acid and glycine betaine on qualitative properties of alfalfa under water stress conditions.
This research was conducted as split plot experiment based on randomized complete blocks design (RCBD) with three replications during 2018-2019 cropping season at Karaj Botanical Research Institute. The main plots consisted of three levels of irrigation (including full irrigation, cut-off irrigation from the beginning of flowering until the end of the growing season, cut-off irrigation from 50% of flowering until the end of the growing season). The sub-plots included foliar application of stress reducing agents with 5 levels (including control (without foliar spraying), 0.5 mM salicylic acid, 1 mM salicylic acid, 10 mM glycine, and 50 mM glycine).
The results indicated that water deficit had a significant effect on all the studied traits and the application of stress-reducing agents effectively mitigated the adverse effects of water stress. Among the qualitative properties, the combined treatment of full irrigation and foliar application of glycine betaine yielded the most favorable results. The use of 10 mM glycine betaine is recommended for enhancing alfalfa's response to water stress. In both stress treatments (i.e., cessation of irrigation from the beginning of flowering and cessation of irrigation from 50% of flowering), the use of stress-reducing treatments resulted in a significant reduction in the negative impact of stress on most traits. So, the difference in means between the treatments with and without stress-reducing agents was significant.
Current research suggests application of stress-reducing agents, such as glycine betaine and salicylic acid, can be beneficial in improving alfalfa's performance under water stress conditions, so contributing to better crop yield and quality. Further research and implementation of these stress-alleviating strategies can offer promising prospects for sustainable alfalfa cultivation in challenging environments.