## 1 Introduction  
Among abiotic stresses, drought is one of the major factors that cause injurious effects to wheat growth and productivity by manipulating its physiological pathways [1]. Wheat (_Tritcium aestivum_ L.) is considered as an important food and cereal crop in the world. Its cultivation has been extended to arid regions to possibly assist in addressing future food security issues in problematic zones where water shortage is the greatest predicament in diminishing wheat crop [2]. Drought stress causes oxidative stress and cellular damage [3], diminished carbon assimilation [4], reduced photosynthesis through the lessening of the synthesis of photosynthetic pigments [5] and limits water retention at the cellular, tissue, and organ levels [1], thereby reducing dry matter production and seed yield [6; 7]. It also disturbs the balance between reactive oxygen species (ROS) and antioxidant enzymes [8], which subsequently leads to electrolyte leakage, the deactivation of various enzymes and membrane damage [9]. Additionally, it has been reported to affect metabolic processes, such as carbon assimilation, turgor pressure and gas exchange, and ultimately cause crop failure [10]. In recent years, different agronomic and physiological approaches have been used to alleviate the adverse effect of drought stress, which include the application of osmoprotactants, growing drought-tolerant varieties and practicing sustainable tillage using natural and synthetic mulches as well as allebotathic crop water extracts. The application of plant hormones has been reported as an emerging and easy-to-adapt strategy for enhancing crop performance under stress conditions [11]. In addition, the use of allebotathic crop water extracts also provides a bio-safe and eco-sustainable alternative for crop enhancement under stress [12]. The effect of the application of allebot chemicals, either for growth stimulation or retardation, is dose-dependent. Hormesis is described as the low-dose stimulation and high-dose inhibition effect of allelochemicals [13]. Brassica napus, a well-known and widely grown species of the Brassica family, is considered as a potential allebotathic crop owing to the presence of potent allelochemicals, such as brassinosteroids, allyl isothi cyanates and glucosinolates [14]. Brassinosteroids (BRs) are polyhydroxy steroidal phytohormones that have a great potential to enhance plant growth [15]. Brassinolide (BL), 28-homobrassinolide (28-HomoBL) and 24-epibrassinolide (24-EpiBL) are the most important classes of BRs [16]. Brassinosteroids (BRs), a discovered class of plant hormones, can play a vital role in various physiological and biochemical processes in plants, such as cell division, cell elongation and expansion, photosynthesis, the synthesis of nucleic acid and proteins, membrane polarization, proton pump activation, ions uptake and transport into the cells and enzyme activation [17]. The exogenous application of BRs through a foliar spray is reported to enhance tolerance to abiotic stresses, including heat, salinity and drought [18; 19]. Under abiotic stresses, the foliar application of BRs modulates physiological and biochemical functions and allows plants to withstand oxidative stress [20]. The authors of [21] documented that BRs improve the developmental and physiological traits under stress. According to [22], BRs also ameliorate oxidative damage through reducing the accumulation of ROS and enhancing the activity of antioxidant enzymes. The authors of [23] reported that the application of brassinolide improves the growth of wheat under moisture deficit conditions. The exogenous application of 24-epibrassinolide, an active form of BRs, ameliorates the drought-induced inhibition of photosynthesis through positively regulating the activity of chloroplast, chlorophyll fluorescence and photosynthetic pigments; the accumulation of osmoprotectants; and the increase in photosynthetic enzyme activity [24].