Construction of a new LED chamber to measure net ecosystem exchange in low vegetation and validation study in grain crops

A vegetation canopy chamber system measures gas exchanges in the field between plants and the environment. Transparent closed chambers have generally been used to measure canopy fluxes in the field, depending on solar radiation as the light source for photosynthesis. However, measuring canopy fluxes in nature can be challenging due to fluctuations in solar radiation. Therefore, we constructed a novel transient-state closed-chamber system using light-emitting diodes (LEDs) as a light source to measure canopy-scale fluxes. The water-cooled chamber system used a 1600 Watt LED module to produce constant photosynthetically active radiation (PAR) and a CO(2) gas analyzer for concentration measurements. We used the LED chamber system to measure barley and wheat gas exchanges in the field to quantify CO(2) fluxes along a PAR gradient. This novel technology enables the determination of photosynthesis rates for various crops under diverse environmental conditions, in diverse ecosystems, and across long-term interannual changes, including those due to climate change.