Drought has become major environmental constraint to the crops productivity and the sustainability of agriculture. Recently, using biochar (BC) as a soil conditioner has aroused much interest and proved to be an effective tool for improving soil properties and crops growth and yield. Therefore, a pot trial was conducted using wheat plant (Triticum aestivum L.) with three water regimes (60, 30 and 15% of water holding capacity(WHC)) and three rates of biochar (0, 2%, and 5%) to investigate the impact of biochar on growth and yield components. The results showed that WHC enhanced in the presence of BC leading to improving the availability of water to wheat plants grown in BC-treated soil. Plants grown in BC-amended soil had higher growth and plant biomass, net assimilation rates than those in un-amended soil. Biochar addition positively affected wheat growth parameters including increases in leaf area, number of leaves per plant, tillers number per plant, height of plant as well as shoot to root fresh weight ratio. Particularly interesting is the improvements in yield attributes. These results led us to conclude that the application of black carbon would enhance the growth and yield of crops under insufficient water supply. On other hand, biochar can be considered an effective tool for sustainable agriculture and hence mitigating the injurious effects of drought conditions on plants.

Two pot experiments were conducted on the 17th and 11th of march during 2015 and 2016 growth seasons respectively at the greenhouse, Dept. Agric. Botany, Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Egypt to investigate the impact of drought stress on some growth, biochemical and anatomical parameters of Thymus vulgaris L. Plants were exposed to two different irrigation levels: 70-80% and 30-40% of water holding capacity (WHC) as well-irrigated and drought stressed plants respectively. The results indicated that all investigated growth parameters and leaf photosynthetic pigments were decreased significantly by exposing to drought stress. There were significant increase in the concentration of reactive oxygen species (ROS) as indicated by measuring of H2O2 and malondialdehyde (MDA). A similar trend was observed in respect to osmolytes including proline, total soluble sugars and free amino acids. Also, drought stress increased significantly total soluble phenols and the specific activity of Phenylalanine ammonia-lyase (PAL) and Polyphenol oxidase (PPO), whereas, no significant differences were detected in peroxidase (POD). The anatomical examination showed that there were several significant changes associated with water limited supply in the stem and leaf of plants.