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 CO2 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) CO2 microenvironments. Two rice varieties contrasting in canopy structure and physiology were grown embedded in irrigated rice paddies, under elevated CO2 (using a Free‐Air CO2 Enrichment facility) and ambient CO2 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 CO2 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.

Effect of foliar spray of kinetin on the enhancement of rice yield by elevated CO2

“…Nitrogen reduction and the stimulated biomass by elevated CO 2 could induce relative nitrogen limitation and shading; thus, in Koshihikari, the response of PD to kinetin at elevated CO 2 may had been affected by the stimulation effect of elevated CO 2 on plant growth and the reduction effect on plant nitrogen. Takanari, however, can maintain plant nitrogen content at elevated CO 2 and is photosynthetically more active and characterized by a more open canopy than Koshihikari (Chen, Sakai, et al., 2014; Muryono et al., 2017; Sikma et al., 2020).…”

Heat-Mitigation Effects of Irrigated Rice-Paddy Fields Under Changing Atmospheric Carbon Dioxide Based on a Coupled Atmosphere and Crop Energy-Balance Model

“…Because the increase in T c shown in Fig. 14 is reasonable compared with the results of the past rice FACE experiments (Yoshimoto et al 2005;Sikma et al 2020), we retain the current model for this study.…”

Current status and prospects of rice canopy temperature research

“…Leaves are the most sensitive organ for the short‐term regulation of canopy temperature; and characteristics such as leaf size, shape, and angle toward the sun affect heat conduction between the rice plant and its environment, which affects canopy temperature (Parkhurst & Loucks, 1972; Smith, 1978). The area around the leaf boundary facilitates convective heat exchange and increasing this area can help reduce the canopy temperature to improve endurance during dry and hot conditions (Sikma et al, 2020). Mathematical analysis has revealed that cumulative temperature rather than non‐cumulative photosynthetically active radiation can trigger exponential canopy growth (Fukuda et al, 2021).…”