Effects of Salicylic Acid and Macro- and Micronutrients through Foliar and Soil Applications on the Agronomic Performance, Physiological Attributes, and Water Productivity of Wheat under Normal and Limited Irrigation in Dry Climatic Conditions

Abstract

Ensuring food security with severe shortages of freshwater and drastic changes in climatic conditions in arid countries requires the urgent development of feasible and user-friendly strategies. Relatively little is known regarding the impacts of the co-application (Co-A) of salicylic acid (SA), macronutrients (Mac), and micronutrients (Mic) through foliar (F) and soil (S) application strategies on field crops under arid and semiarid climatic conditions. A two-year field experiment was designed to compare the impacts of seven (Co-A) treatments of this strategy, including a control, FSA+Mic, FSA+Mac, SSA + FMic, SSA + FSA+Mic, SSA+Mic + FSA, and SSA+Mic + FMac+Mic on the agronomic performance, physiological attributes, and water productivity (WP) of wheat under normal (NI) and limited (LMI) irrigation conditions. The results reveal that the LMI treatment caused a significant reduction in various traits related to the growth (plant height, tiller and green leaf numbers, leaf area index, and shoot dry weight), physiology (relative water content and chlorophyll pigments), and yield components (spike length, grain weight and grain numbers per spike, thousand-grain weight, and harvest index) of wheat by 11.4–47.8%, 21.8–39.8%, and 16.4–42.3%, respectively, while WP increased by 13.3% compared to the NI treatment. The different Co-A treatments have shown a 0.2–23.7%, 3.6–26.7%, 2.3–21.6%, and 12.2–25.0% increase in various traits related to growth, physiology, yield, and WP, respectively, in comparison to the control treatment. The SSA+ FSA+Mic was determined as the best treatment that achieved the best results for all studied traits under both irrigation conditions, followed by FSA+Mic and SSA+Mic + FSA under LMI in addition to FSA+Mac under NI conditions. It can be concluded that the Co-A of essential plant nutrients along with SA accomplished a feasible, profitable, and easy-to-use strategy to attenuate the negative impacts of deficit irrigation stress, along with the further improvement in the growth and production of wheat under NI conditions.

Advances in Roles of Salicylic Acid in Plant Tolerance Responses to Biotic and Abiotic Stresses

“…However, the exact mechanisms in this process are not yet fully understood [78]. In a word, recent studies made remarkable advances in SA's roles in plant tolerance responses to both biotic and abiotic stresses [47,48,71,72,82,84,[86][87][88][118][119][120][121][122][123], and in both physiological [124][125][126] and molecular perspectives [127][128][129][130]. For example, Yao et al proposed a high air humidity-triggered significant suppression of SA accumulation and signaling associated with compromised immunity of Arabidopsis plants [130], which indicates the value of research concerning SA's roles in multiple stresses confronted by plants.…”

“…Effective mitigation of adverse impact; facilitation of better germination and early seedling growth; maintenance of relative water content, membrane stability and overall plant growth [77] salt wheat Alleviation of plant growth inhibition; increment of N, P, and K + acquisition; enhancement of endogenous SA and SPM levels by exogenous SA and/or SPM applications [82] salt St John's wort Improvement of growth [83] salt wheat Salt stress alleviation by SA and/or SPM; significant improvement of growth and production [84] drought wheat Substantial reduction of drought influence, and enhancement of grain yield and water use efficiency by co-application of K + and SA [85] dry climatic conditions wheat Attenuation of deficit irrigation, and improvement of growth and production by co-application of essential plant nutrients and SA [86] drought wheat Regulation of stress response [87] cadmium tomato Significant reduction of cell wall Cd accumulation; changes in Cd distribution [90] waterlogging stress soybean Reduction of some physiological indexes by SA and KN; enhancement of antioxidant defense by SA and KN; effective improvement of ROS metabolism and waterlogging stress tolerance [94] salt cashew Attenuation of salt stress; increment of photosynthetic pigment synthesis [97] drought oregano Improvement of PSII efficiency under moderate drought stress [98] water deficit and nutrient deprivation Sempervivum tectorum L.…”

“…As a consequence of biotic stresses, under drought conditions, plants become more susceptible to pest and disease infestation, as their defense mechanisms are weakened. The harms caused by drought stress significantly impact plant growth, development, crop yield, and quality [86,98].…”

“…New research has shown that SA plays multiple roles in enhancing plant stress resistances [32,38,43,73,77]. Such roles of SA can be categorized into the following aspects: immune response [13,25,[78][79][80], antioxidative defense [11,20,[53][54][55][56][57][58][59], salt tolerance [43][44][45]47,48,[81][82][83][84], and drought tolerance [2,11,[32][33][34][35][36]71,[85][86][87].…”

Enhancing Wheat Growth, Physiology, Yield, and Water Use Efficiency under Deficit Irrigation by Integrating Foliar Application of Salicylic Acid and Nutrients at Critical Growth Stages

“…For example, spraying wheat plants with SA and zinc reduced the negative effects of water deficiency, leading to increased chlorophyll content, relative water content, plant height, spike length, number of grains per spike, 1000-grain weight, grain yield, and water use efficiency [ 35 ]. Likewise, Alotaibi et al [ 36 ] concluded that combining micronutrients with SA is more effective in enhancing the growth, yield parameters, and irrigation water use efficiency (IWUE) of wheat plants under water deficit compared to using these compounds individually. Safar-Noori et al [ 37 ] found that combining SA with a sufficient amount of K enhanced wheat growth and production under drought stress more effectively than applying them separately.…”