Mitigation of Salinity Stress by Application of Plant Growth Promoting Substances in Rice

Aim: Salt stress adversely affects plant growth and development. Various mitigating strategies have been employed to enhance the adaptability of plants to salt stress. The present study was conducted with the objective of evaluating the recently developed CO55 rice variety's ability to withstand salt-induced stress during seedling growth. This evaluation included foliar spraying of plant growth promoting substances like melatonin, salicylic acid, silicon, and selenium, along with the identification of effective plant growth-promoting substances that exhibit tolerance to salinity. This study is required to develop salt-tolerant varieties capable of withstanding salinity stress during the seedling stage. The seedling stage is more susceptible to salinity, and also to increase the growth and yield of rice, thereby satisfying the country's agricultural needs.

Study Design: Completely randomized design.

Place and Duration of Study: Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore; March-April 2023.

Methodology: In the hydroponics experiment, the CO55 rice variety was subjected to foliar spraying of various plant growth promoting substances such as melatonin, salicylic acid, orthosilicic acid, and sodium selenate. Parameters like leaf drying score, osmotic potential, osmotic adjustment, sodium content, potassium content, and Na+/K+ ratio were assessed. One-way ANOVA was used to analyze the data.

Results: Specific pairwise differences between means were assessed at the 0.05 significance level using Fisher's least significant difference (LSD) test. Among the treatments applied, salicylic acid recorded the highest potassium content (3.94%), and the lowest potassium content (2.60%) was found in orthosilicic acid. On the other hand, from the standard evaluation score, it was observed that CO55 rice variety seedlings were found to be tolerant when treated with salicylic acid, whereas it was susceptible under orthosilicic acid treatment.

Conclusion: Observations indicated that foliar application of salicylic acid at the concentrations of 50µM and 100µM exhibited higher tolerance towards salinity during the seedling growth stages.