Mitigation of Morpho-biochemical Attributes of Saline Stressed Rice (Oryza sativa L.) Seedling with 50 and 100-µM Abscisic Acid (ABA) Treatments
Ikram-ul Haq1*, Nazia Parveen Gill2, Faheeda Soomro3, Zainab Soomro1,
Mehwish Baloch1, Chanda Bakhtawar Baloch1, Sanam Nawaz1,
Asra Mahar1, and Javeria Nizamani1
1Institute of Biotechnology and Genetic Engineering (IBGE),
University of Sindh, Jamshoro 76080 Pakistan
2Department of Statistics, University of Sindh, Jamshoro 76080 Pakistan
3Department of Linguistics and Human Sciences,
Begum Nusrat Bhutto Women University, Sukkur 65200 Pakistan
ABSTRACT
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: Na2SO4, 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 (H2O2), 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.
INTRODUCTION
Plant growth as well as its yields have been decreasing continuously mainly due to salinity as among the environmental stresses (van Zelm et al. 2020). It is represented as the major hurdle in the expansion of agricultural areas to increase yields of crops (Reddy et al. 2017). Increasing soil salinity has distributed nearly 71 % of the Earth’s area (Li et al. 2018). Mainly the retention of NaCl with or Na2SO4 (neutral) and NaHCO3 with or Na2CO3 (alkaline) salts causes soil salinization. . . . . . read more
