Rice Waste Hydrolyzation at Subcritical Temperature to Produce Bioherbicide to Control Terrestrial Weeds

Abstract

Thermal anaerobic hydrolyzation process on rice husk with higher lignin content produced organic complexes constituents including phenolic groups. Phenolic groups expose herbicide effects on growing vegetations, where the process in nature mainly require anaerobic condition. The degradation rate in nature is very slow with very low concentration availability. Thermal hydrolyzation is an appropriate choice to produce phenolics herbicide for sustainable pesticide management and application. This study aimed to identify the potency of rice husk extract by thermal hydrolyzation process as an organic herbicide to control terrestrial weeds. The hydrolyzation was processed in 60-90 bars and 280±20 °C for 30±10 minutes. The existence of the phenolic groups in the hydrolysate was considered for generic active ingredients to control weed in the terrestrial ecosystem. Its damage impact was tested on Borreria alata, Eleusine indica, Cyperus kyllingia, Paspalum conjugatum, Asystasia intrusa, and Axonopus compressus. The assay covered the growth at pre-emergence, early post-emergence, and post-emergence growing stages. The rice waste hydrolysate was capable to suppress the growth of the weed growth especially at the pre-emergence stage at 30-64%, and at early post-emergence stages at the suppressing rate of 77-100%. However, the suppressing affectivity is lower at the post-emergence stage which only 17-25%.