Punched-top chamber for moderately raising air temperature during the ripening period in rice

ABSTRACT Rice growth at an elevated air temperature (T air) during the ripening period is often evaluated using a semi-closed chamber (SCC). However, the water vapor pressure deficit (VPD) and CO2 concentration inside SCCs get lower than at ambient air plot, and these changes affect panicle temperature and photosynthesis. We developed a punched-top chamber (PTC), that is, an SCC with numerous pores on the top, and compared meteorological environments inside the two chambers and of ambient air plot. When solar radiation was >200 W m-2, ΔT air (SCC – Ambient) was 3.1°C–5.3°C, and ΔT air (PTC – Ambient) was 2.2°C–3.7°C. Excessively high T air > 38°C were more frequent inside the SCC than the PTC. The changes in VPD and CO2 concentration inside the PTC were less pronounced compared with those of the SCC, and thus PTC can be a better treatment for safely assessing the direct effect of elevated T air. Graphical abstract