PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Weed competition during soybean cultivation induces stress, leading to reduced yields. One of the dominant weeds in soybean cultivation is Tridax procumbens, and weed control is generally performed using herbicides, but can cause environmental pollution. Therefore, natural herbicides that are environmentally friendly and sustainable are required. Teak leaves, which contain allelopathy and are abundantly available in Indonesia, have the potential to be used as a bioherbicide. This study aimed to determine the optimal concentration and application time of teak leaf extract as a bioherbicidal agent against T. procumbens during soybean cultivation. The study was performed at the laboratory and greenhouse of the Faculty of Agriculture, Universitas Gadjah Mada, Sleman, Special Region of Yogyakarta. The research was conducted in two stages. The first stage was the germination stage, which used a complete randomised design with 10%, 20%, and 40% teak leaf extract concentrations. Meanwhile, the second stage was the initial growth stage using a complete randomised block design with treatments consisting of application 7 days pre-planting, planting time, and application 7 days post-planting. The 10% concentration of teak leaves was able to inhibit the germination force and vigour index of T. procumbens and did not inhibit soybean germination. Therefore, a 10% teak leaf extract concentration was applied in the second stage, and optimal results at the time of application at planting were obtained because it was able to inhibit up to 100% of T. procumbens growth. However, further field-scale studies are needed to evaluate its practical application.