Salicylic Acid Improves Rice Seed Germination under Induced Drought Stress

Abstract

R ice is one of the most important food commodities and provides major portion of daily calories requirement, especially in underdeveloped and developing countries (Fukagawa and Ziska, 2019). The world population is increasing at an exponential rate, demanding approximately 70% increase in food production to meet the food security targets by 2050 (Fróna et al., 2014). Water scarcity or drought is one of the biggest threats to food security worldwide and could reduce crop production by 50% (Budak et al., 2015). Therefore, management of drought stress is crucial for successfully achieving the desired production targets. About 77% of the total cultivated rice is conventionally transplanted globally Abstract | Rice is the staple food of more than 50% of the world's population, and water scarcity is threating its sustainable production. Dry seeded rice (DSR) technology has water and labour saving advantages over conventional transplanting culture, however, poor crop establishment due to reduced germination in variable field conditions greatly hampers its large-scale adaption. To address subordinate germination issues, we investigated the effects of five salicylic acid (SA) concentrations (0, 75, 150, 225 and 300 ppm) on polyethylene glycol (PEG) induced drought stress conditions (0, -0.2, -0.4, -0.6 and -0.8 MPa). Highly significant (p < 0.01) effects of drought, SA and their interactions were observed on seed germination. Interestingly, varying SA concentrations imparted more pronounced effects under higher osmotic stress levels. Day-wise germination data indicated that the SA treatments alleviated inhibitory effects of different osmotic stress levels after 2-4 days of stress applications. Under medium to high osmotic stress levels, mean germination time, germination index and seed vigour index (SVI) of SA primed seeds were better than non-primed seeds. Remarkably, SVI of all SA concentrations under -0.2 MPa osmotic stress was surprisingly improved as compared with control and other osmotic stress levels, indicating a 'drought-escape strategy' in rice seeds under low osmotic stress level. Overall, our results indicated that seed priming with 225 ppm SA concentration is ideal under all environments and should be recommended in DSR system to improve early crop establishment and sustainable production.

Exogenously Applied Salicylic Acid Boosts Morpho-Physiological Traits, Yield, and Water Productivity of Lowland Rice under Normal and Deficit Irrigation

“…In this study, a significant mean square due to the main effects of irrigation conditions, cultivars, SA, as well as their interactions on grain yield and most studied traits was observed. The significant effects of cultivars, irrigation conditions, SA, and their interactions on rice quantitative traits were previously reported by [18,20,21,38,46,47]. The irrigation conditions, followed by cultivars and SA concentrations, determined a large proportion of the total variation in the grain yield and most studied traits.…”

“…The genetic variation between rice cultivars is fundamental to the development of drought tolerance cultivars because they react reversibly to drought stress [49]. Under higher osmotic stress levels, the variation of SA concentrations shows more pronounced effects [21]. These indicate that there was sufficient desirable variability in the two rice cultivars' responses to SA concentrations under normal and drought irrigation conditions, which may be utilized in improving the rice grain yield under drought regions in Egypt.…”

“…Some researchers believe in selection under favorable conditions [21] and some believe in selection under typical drought conditions [22]. Nevertheless, there exist numerous researchers that chose the midway and believe in selection under both favorable and stressed conditions [23][24][25].…”

Conditioning white oat seeds in salicylic acid to mitigate salt stress

“…Furthermore, in Hordeum marinum and H. vulgare, seed conditioning with SA significantly improved aerial and root growth under different salt treatments (up to 200 mM), suggesting that the effectiveness of this approach may vary with the species and the intensity of stress applied (YOUSSEF et al, 2023). And treatment with salicylic acid may be one of the suitable alternatives to reduce the deleterious effects of salt stress in rice, where joint application improved its vegetative characteristics and showed beneficial effects on seed germination and seedling vigor index (FARHANGJOO et al, 2020;RAFIQ et al, 2021).…”

“…In addition, it acts as a signaling molecule that induces plant tolerance to stress by regulating physiological processes and providing protection against biotic and abiotic stresses, such as those caused by excess salt in the substrate (SILVA et al, 2020). In this regard, several authors have reported that the exogenous application of salicylic acid increases plant tolerance to salt stress, as observed for example in rice (FARHANGJOO et al, 2020;RAFIQ et al, 2021), pepper (KUMAR et al, 2022), wheat (ABDI et al, 2023, sugarcane (APON et al, 2023), eggplant (MADY et al, 2023), and barley (YOUSSEF et al, 2023.…”