Effects of salicylic acid on growth, photosynthesis pigment, proline and endogenous hormones content of black rice grown under salt stress

Salinity is one of the abiotic stresses that inhibits plant growth and development. One of the mechanisms by which plants tolerance to salinity is through synthesizing salicylic acid (SA). This research was aimed to evaluate the impact of SA on growth, photosynthesis pigments, proline accumulation and endogenous hormone levels of black rice ‘Sembada Hitam' subjected to saline conditions. Black rice seeds were germinated in a plastic tray containing growth media and seedlings of 3 weeks old were transplanted into a plastic chamber with similar growth media. Sodium chloride of 0 mM (control), 50 mM, 100 mM or 150 mM were applied 1 month after planting, whereas plants were sprayed with different concentration of SA, namely 0 mM (control), 0.5 mM, 1 mM or 2 mM at 25, 50, 75 and 90 days after planting. Five replicates were prepared for each treatment combination. Several growth parameters such as plant height, root length, number of tillers and flag leaf area and physiological parameters such as chlorophyll, carotenoids, proline and endogenous hormones content were determined. The results indicated that salinity inhibited the growth parameters of 'Sembada Hitam' rice. Elevated sodium chloride levels resulted in reductions in plant height, root length, number of tillers and flag leaf area. Application of SA mitigated the adverse effects of salinity by enhancing plant height, root length, number of tillers and flag leaf area. The presence of SA also led to increase levels of Indole-3-Acetic Acid (IAA), Gibberellins (GA3), Cytokinins (CKs), Jasmonic Acid (JA) and endogenous Salicylic Acid (SA), while reducing Abscisic Acid (ABA) levels in black rice under saline conditions. © The Author(s).