The need for a more efficient agricultural production system has arisen due to factors such as rapid urbanization, climatic anomalies, water scarcity, and declining water quality in modern times. Bedding plants are one of the integral parts of the landscape and the African marigold is one of the most common and particularly popular. This study investigates the effects of biochar and zeolite on the morphological and biochemical properties, as well as the photosynthetic performance, of African marigold (Tagetes erecta L.) plants. The experiment followed a completely randomized design with four treatments: soil mixture alone (control), soil mixture amended with 10% (w/w) biochar, or 25 g zeolite kg-1, or a combination of both. Results indicated that biochar had a significant positive effect on the maximum quantum efficiency of photosystem II (Fv/Fm). On the other hand, zeolite alone significantly improved various growth parameters, including root and stem length, weight, turgor, flower length, plant height, and Fv/Fm, when compared to the control group. However, the use of zeolite also resulted in reductions in chlorophyll content and dry flower weight. Interestingly, the combined treatment of biochar and zeolite led to a significant increase in total soluble carbohydrates. However, this combined treatment did not have a significant impact on most other growth and Fv/Fm parameters. These findings suggest that while biochar and zeolite have positive effects on specific aspects of African marigold growth and physiology, their combined application may not be optimal.
