This study investigated the effects of rice husk biochar and zeolite on the growth parameters of African marigold (Tagetes erecta L.) in a greenhouse condition. A completely randomized design with five treatments and five replicates was used. The treatments included a control (soil mixture), soil amended with biochar, soil supplemented with zeolite, and a combination of biochar and zeolite. The findings revealed that zeolite treatment significantly enhanced flower length, plant height, root length, fresh weight, and stem fresh weight compared to the control and other media combinations. The high cation exchange capacity (CEC) of zeolite likely facilitated improved nutrient availability for the plants, contributing to their superior growth. Biochar did not have a significant effect on any of the parameters in this study. Future research could explore the optimal application rates of biochar and zeolite, as well as their combined effects on essential oil yield and quality in African marigold, to further optimize cultivation practices.
