Effect of Biochar on Physiological Responses and Growth Mechanisms of C4 and CAM Plants under Water Stress

Two open–air pot experiments were conducted with Paspalum vaginatum (C4) and Argania spinosa (CAM), using sandy loam and loam soils, respectively. Biochar and compost were incorporated at varying proportions, and plants were maintained at 20% of field capacity for three growing seasons. A comprehensive set of parameters for both plant species, including plant biomass, photosynthetic rates, chlorophyll concentration, stomatal features, and relative water content (RWC) were measured. Additionally, pH and electrical conductivity were measured for both soil types. Statistical analyses were performed to evaluate the impact of banana waste biochar and compost on soil characteristics and to understand the physiological response mechanisms of the C4 and CAM plants. The application of biochar significantly improved soil fertility and increased the chlorophyll content in the leaves of both Argania spinosa and Paspalum vaginatum when compared to control treatments. The decomposition of biochar led to nutrient accumulation in the soil, which in turn substantially enhanced the physiological traits of both species. These positive effects were particularly evident during the summer season, showing a marked improvement over the winter and spring periods. Moreover, the application of biochar and compost in combination was found to reduce the water requirements of Paspalum vaginatum. The most beneficial results were achieved with the incorporation of 6% banana waste biochar along with 6% compost into the soil. This specific blend led to significant improvements in chlorophyll levels, soil fertility, and drought tolerance for both studied species, especially during the summer months, demonstrating a marked advantage over the control group maintained at 20% field capacity. The study concludes that these findings hold significant potential for applications in golf management, offering a method to reduce irrigation needs. Furthermore, the approach serves as a promising solution for sustainable agriculture practices, particularly in arid regions where water conservation is critical. Keywords: Drought, banana waste biochar, Argania spinosa, Paspalum vaginatum, physiological responses.