Exogenous foliar application of abscisic acid on polyethylene glycol induced drought by improving the morphological and biochemical characters of four rice (Oryza sativa L.) varieties

Abstract

Climate change is one of the critical defining concerns today's world, alter-ing earth ecosystem. Drought stress management is a major issue in agricul-tural and crop research, mainly negatively impacting rice growth and yield. Abscisic acid (ABA) is a plant stress hormone that plays a crucial role in regu-lating, and mitigating drought stress. The objective of this study was to eval-uate the effect of exogenously applied ABA and adaptation strategies re-sponding to concrete challenges in four rice varieties (ASD-16, ADT-45, TKM- 13 and CO-50) and analysed growth characteristics, physiological, biochem-ical and antioxidative enzyme activities induced by polyethylene glycol (2 % and 4 %) drought stress and exogenous application of ABA (100 μM). The present findings help to predict the degree of drought resistance variety of rice. The experiment was designed by six different treatments, such as con-trol plants, control + ABA, polyethylene glycol induced drought (2 % and 4 %), and combination treatment of 2 % and 4 % PEG with exogenous applica-tion of ABA (100 μM). Exogenous ABA treatment significantly increased in morphological characteristics compared to control. The chlorophyll pig-ments, RWC, biochemical parameters such as reducing sugar, starch, pro-tein and antioxidant activities of CAT, POD were increased and proline con-tent was decreased at PEG 2 % and 100 μM ABA-treated rice in TKM-13 com-pared to ASD-16, ADT-45, CO-50. There were statistically significant morpho-logical, physiological and biochemical parameters between treatments. The present findings depict that four rice varieties under drought imposition decrease the growth characteristics, physiological and biochemical content. However, the PEG induced drought (2 %) and foliar application of ABA (100 μM) were found to increase morphology, physiological and biochemical contents and can provide valuable insights into plants' drought responses and may help identify novel drought tolerance traits.