In most plants, increased CO2 reduces water use or transpiration. This is because the pores in the leaves – stomata – partially close, reducing water loss. The effect can be significant. For example, a free air CO2 enrichment (FACE) study on wheat showed that water-use efficiency was 19% higher under elevated CO2. This may be particularly important [...]

The yield or growth rate of most vegetable crops is likely to increase as atmospheric CO2 levels rise. This effect is well known in the glasshouse industry where CO2 enrichment has been practiced for many years for crops such as tomatoes, cucumbers, capsicums and leafy vegetables. Global CO2 levels have just recently reached 400ppm, up from 320ppm [...]

Water use by vegetable crops is mainly determined by loss into the atmosphere, rather than availability in the soil. The atmospheric demand for water is estimated by the potential evapotranspiration (PET). Four factors influence PET: Temperature Wind speed Sunshine Relative humidity Increases in temperature can be offset by decreases in sunshine, due to cloudy conditions, [...]