Interactive effects of brassinosteroids and timber waste biochar enhances the drought tolerance capacity of wheat plant

Abstract Drought stress is among the major constraints that threat agricultural productivity within the arid and semi-arid regions, worldwide. In this study, wheat (a strategic crop) was selected to test its growth under drought stress and the mechanisms beyond this adaptation while considering two factors, i.e., (1) deficit irrigation at 35% of the water holding capacity (WHC) versus 75% of WHC (Factor A) and (2) the following safe treatments: the control treatment (C), amending soil with biochar (BC) at a rate of 2%, foliar application of 24-epibrassinolide at two different levels (1 (BR1) or 3 (BR2) µmol) and the combination between BC and BR treatments. The obtained results were statistically analyzed, and the heat-map conceits between measured variables were also calculated by using the Python software. This investigation took place under the greenhouse conditions for 35 days following a complete randomized design and all treatments were replicated trice. Results obtained herein revealed that drought stress decreased all studied vegetative growth parameters (root and shoot biomasses) and photosynthetic pigments (chlorophyll a, b and total contents while increased oxidative stress indicators. All additives, specifically the combined ones BR1 + BC and BR2 + BC, were effective in increasing growth attributes, photosynthetic pigments and ion assimilation by wheat plants. They also upraised the levels of enzymatic and non-enzymatic antioxidants while decreased stress indicators. Furthermore, they increased Ca, P and K content within plants. It can therefore be deduced that the integral application of BR and BC is essential to mitigate drought stress in plants.