| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1711505 | Biosystems Engineering | 2012 | 8 Pages |
Net photosynthetic rate of whole-plant (Pn) can be used to estimate plant growth and CO2 use efficiency (CUE) in a ‘closed system with artificial lighting’ (CSAL). CUE is defined as the ratio of the canopy net photosynthetic rate in a CSAL to the CO2 supply rate. Pn can be estimated based on the CO2 balance in the CSAL if the air exchange rate is known. The air exchange rate is usually estimated using CO2 as a tracer gas, but this method cannot be applied in the presence of plants. We propose a method for estimating Pn in a CSAL based on the air exchange rate estimated using water vapour instead of CO2 as a tracer gas. In this study, a growth chamber was used as an experimental CSAL. The air exchange rate was defined as the number of air exchanges per hour (N), which is the ratio of the hourly exchanged air volume to the air volume of the CSAL. Firstly, N was estimated using water vapour (NW) and CO2 (NC) as tracer gases in the absence of plants. Then, Pn and CUE of the tomato plants were estimated using the proposed method. The results showed that NW agreed well with NC, and Pn was accurately estimated by the proposed method. The estimated CUE decreased with increases in N and CO2 concentration inside the growth chamber. It was concluded that the method can be used to estimate Pn and CUE in a CSAL.
► Water vapour proposed as tracer to estimate air exchange rate in semi-closed chamber. ► Air exchange rate estimated using water vapour agreed well with estimate using CO2. ► Net photosynthetic rate of whole-plant was accurately estimated by proposed method.
