Enhancing Sustainable Rice Production through Charged Biochar and Arbuscular Mycorrhizal Fungi in a Pruned–Ratoon Cropping System

Abstract

Rice productivity in ratoon systems is often constrained by reduced root activity, limited nutrient uptake, and insufficient photoassimilate supply. This study evaluated the interaction of arbuscular mycorrhizal fungi (AMF)(0, 5, and 10%) and charged biochar (0, 2.5, and 5 t ha−1) on rice growth and yield under unpruned, pruned, and ratoon management systems across two growing seasons. In the second season, rice was grown as a ratoon crop to assess the residual effects of AMF and biochar applied in the first season. Inorganic fertilizer rates were adjusted according to biochar treatments (100%, 50%, and 0% of the recommended rate for B0, B1, and B2, respectively). The interaction between AMF and charged biochar significantly increased productive tillers, grains per panicle, harvest index, and grain yield during the main crop season, with the highest yield obtained under the unpruned C1B2 treatment (5% AMF + 5 t ha−1 charged biochar). The B2 treatment also supported ratoon rice production without inorganic fertilizer application. Although no residual effects were detected on grain yield and harvest index, the findings suggest that the integrated use of charged biochar and AMF has the potential to improve rice productivity while reducing dependence on inorganic fertilizers, thereby supporting more sustainable rice production systems.