Combined effects of resistant rice cultivar and organic fertilizer on plant–soil responses to aboveground brown planthopper

Resistant rice cultivar and organic fertilizer suppressed brown planthopper performance. Both factors mitigated BPH-induced declined in plant growth and soil microbial biomass. Organic fertilizer reduced root-feeding nematodes and stabilized soil food web structure. Cultivar and fertilizer acted independently, offering a sustainable pest-nutrient strategy. Plant-herbivore interactions are strongly shaped by plant genotype and soil resource availability, but studies that jointly consider these factors within an integrated aboveground-belowground framework remain limited. This knowledge gap constrains the optimization of cultivar breeding and fertilizer management for sustainable agriculture. We conducted a factorial greenhouse experiment with three factors, brown planthopper (BPH, Nilaparvata lugens Stål) infestation (present/absent), rice cultivar (resistant or susceptible), and fertilizer type (chemical or organic), to test how cultivar and fertilizer affect rice resistance to BPH and, in turn, how BPH alters soil nutrient availability, microbial biomass, and nematode communities through plant-mediated pathways. Both resistant cultivar and organic fertilizer significantly suppressed BPH performance relative to susceptible cultivar and chemical fertilizer. They also mitigated BPH-induced reductions in plant growth, microbial biomass, soil resources, and bacterial- and fungal-feeding nematodes. In contrast, chemical fertilizer exacerbated BPH impacts, particularly on susceptible rice, and promoted root-feeding nematodes. Cultivar and fertilizer independently affected plant and soil responses without showing synergistic interaction. Our findings suggest that combining resistant cultivars with organic fertilizer strengthens resistance to aboveground herbivores and belowground root-feeding nematodes, while enhancing soil resources and food web stability. This integrated strategy provides an effective approach for sustainable pest management and nutrient regulation in rice systems. (Figure presented.)