Philippine Journal of Science
154 No. 1: 159-167, February 2025
ISSN 0031 – 7683
Date Received: 21 Aug 2024

Ikram-ul Haq, Nazia Parveen Gill, Faheeda Soomro, Zainab Soomr, Mehwish Baloch, Chanda Bakhtawar Baloch, Sanam Nawaz, Asra Mahar, and Javeria Nizamani

Phytohormones act as signal transmitter molecules to manage abiotic stresses and regulate plant morphogenesis. Abscisic acid (ABA) responds under toxic salt stress as a signal passed at danger in the regulation of plant metabolism. The seed germination rate has been considered as the key to final crop yields. In this study alleviation effect of ABA (50 and 100 µM) on germination than subsequent growth of Basmati-370 cultivar of rice (Oryza sativa L.) seedlings stressed under 150-mM salts (NaCl: Na2 SO4 , 9:1, pH 6.45 ± 1) for 2 wk were assessed. In the 1st week, both ABA and salts were sprayed to moisturize the filter paper on which seeds were sown, whereas in the 2nd week, only ABA was foliarly sprayed. ABA decreases in gibberellic acid (GA3 ) concentrations and α-amylases activities of control (without salts) and salt-stressed seeds, which results in a significant decrease in seed germination (%) rate. Salinity significantly decreases seedling growth, relative water contents, pigments, K+, proteins, and total sugars, whereas reducing sugars, malondialdehyde (MDA), proline contents, hydrogen peroxide (H2 O2 ), Na+ and Cl– increased (p ≤ 0.05). These above observations were measured as reversed due to the ameliorated effects of ABA supplementation. In conclusion, an increase in ABA levels leads to a decrease in GA3 contents at the seed germination stage, which contributes toward a lower seed germination rate, whereas after germination exogenous ABA applications enhance salt tolerance by promoting nutrient uptake and balancing endogenous hormones to accelerate seedlings growth effectively.