Divergent regulation of rice yield by carbon nanomaterials via biomass allocation and seed setting rate

Introduction Nanomaterials (NMs) technology has shown great potential in sustainable agriculture. However, comprehensive assessments of their impacts on the entire rice growth stages, particularly from vegetative to reproductive periods, are still limited. Methods Herein, two carbon NMs, graphitic carbon nitride (C 3 N 4 ) and graphene, were applied via daily foliar spraying for 7 days at the rice tillering, jointing, flowering and ripening stages to systematically investigate their effects on rice growth dynamics. Results Our results revealed that both C 3 N 4 and graphene primarily affect rice growth during reproductive stages (flowering and ripening) rather than vegetative stages (tillering and jointing), with contrasting effects. C 3 N 4 inhibited the transfer of dry biomass from vegetative organs (stems and leaves) to reproductive organs (panicle and grains), resulting in a marked reduction in seed setting rate by 34.5% and consequently a sharp yield decline by 45.1%. Conversely, graphene facilitated the allocation of more biomass to reproductive organs than vegetative organs, and increased seed setting rate by 10.7%, resulting in 11.8% higher rice yield. Discussion Our findings underscore the differential influence of carbon NMs on rice growth mediated through modulation of biomass partitioning and seed setting rate, which is of significant relevance for developing nano-enabled strategies to promote global food security.