Plant-soil feedback in the interference of allelopathic rice with barnyardgrass

Abstract

Despite increasing knowledge of the interference of allelopathic rice with barnyardgrass mediated by allelochemicals, the interference mechanisms are still being elucidated. Here we test whether the interference of allelopathic rice with barnyardgrass may be interpreted from the perspective of plant-soil feedback. We grew barnyardgrass in the soil previously grown with allelopathic rice at the seedling and mature stages in relation to monoculture and mixed-culture and examined the performance of barnyardgrass. We quantified soil allelochemicals and analyzed soil nutrients and microbial communities. Barnyardgrass biomass in soil trained by allelopathic rice PI312777 seedlings was reduced significantly when compared with non-allelopathic rice Liaojing-9 and barnyardgrass seedlings. The performance differences were strengthened by mixed-culture with allelopathic rice seedlings or when incubated with their root exudates and trained soils. In contrast, increased biomass of barnyardgrass in the allelopathic rice soil was observed at the mature stage. At the seedling stage, allelochemical concentrations were much higher in the allelopathic than in the non-allelopathic rice soils. At the mature stage, however, allelochemicals were not detected in the soils. Soil nutrients and phospholipid fatty acids profiles showed that negative feedback at the seedling stage was independent of allelochemicals and microbial communities while positive feedback at the mature stage was more related to nutrients than to allelochemicals and microbial communities. Plant-soil feedback contributes to the interference of allelopathic rice with barnyardgrass, and allelochemical context alters plant-soil feedback at different growth stages.