Quantifying the Feedback Between Rice Architecture, Physiology, and Microclimate Under Current and Future CO₂ Conditions

Abstract To assess the micrometeorological consequences of rice variety choices in relation to rising CO 2 associated to climate change, we quantified the interplay between rice architecture, physiology, and microclimate in current (~385 μmol mol −1 ) and future (~580 μmol mol −1 ) CO 2 microenvironments. Two rice varieties contrasting in canopy structure and physiology were grown embedded in irrigated rice paddies, under elevated CO 2 (using a Free‐Air CO 2 Enrichment facility) and ambient CO 2 conditions. The high‐yielding indica variety Takanari is more photosynthetically active and characterized by a more open canopy than a commonly cultivated variety Koshihikari . Our results show a strong diurnal interplay between solar angle, canopy structure, plant physiology, and the overlying atmosphere. Plant architecture was identified as a strong determinant of the relation between plant physiology and microclimate that in turn affects the surface forcing to the overlying atmosphere. Takanari was able to maintain lower canopy temperature both in current and future CO 2 owing to the greater atmospheric mixing and stomatal conductance than Koshihikari. In the perspective of food security, a shift to such a higher‐yielding variety would have consequences on the regional surface energy balance, which subsequently might alter regional weather.