Optimizing rice plant photosynthate allocation reduces N2O emissions from paddy fields

Area of Science:

• Agricultural Science
• Environmental Science
• Plant Physiology

Background:

• Rice paddies are significant sources of anthropogenic nitrous oxide (N2O) emissions.
• Alternate wetting-drying irrigation and high nitrogen input exacerbate N2O emissions.
• Increasing photosynthate allocation to grain is a strategy for rice yield enhancement, but its effect on N2O emissions is unknown.

Purpose of the Study:

• To investigate the impact of rice plant photosynthate allocation on nitrous oxide (N2O) emissions.
• To determine the relationship between harvest index (HI) and N2O fluxes in rice paddies.
• To explore how manipulating photosynthate allocation affects belowground biomass, nitrogen uptake, and soil properties.

Main Methods:

• Conducted three experiments: variety trials, a mutant study, and spikelet clipping.
• Measured N2O fluxes from rice paddies under different photosynthate allocation scenarios.
• Assessed biomass accumulation, nitrogen uptake, root biomass, soil dissolved organic carbon, and soil denitrification potential.

Main Results:

• N2O fluxes were negatively correlated with the harvest index (HI) (P < 0.01).
• Higher HI was associated with increased biomass accumulation and nitrogen uptake post-anthesis (P < 0.05).
• Reducing photosynthate allocation to grain increased root biomass, soil dissolved organic carbon, and soil denitrification potential (P < 0.05).

Conclusions:

• Optimizing photosynthate allocation to rice grain can significantly reduce paddy N2O emissions.
• This optimization decreases belowground carbon input and enhances plant nitrogen uptake.
• Genetic and agronomic strategies can potentially increase rice yield while lowering N2O emissions.