| Dynamic simulation of instantaneous water use efficiency in apple leaves |
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| DOI：10.7606/j.issn.1000-7601.2011.03.19 |
| Key Words: apple instantaneous water use efficiency simulation microclimate |
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| Abstract: |
| We developed a model that coupled leaves net photosynthetic rate ，transpiration rate and instantaneous
water use efficiency (WUEI) and tested against observational data from an apple orchard. The sensitivity of WUEI to mi-croclimatic factors and leaf water potential (Ψ1) was systemically assessed in this model. The leaves photosynthetic and transpiration rates were simulated by the C3 photosynthesis model and Penman Monteith equation. For convenience,
WUEI was expressed as the ratio of net photosynthetic rate to transpiration rate. It was shown that WUEI increased rapid-ly with increasing CO2 concentration and relative humidity (RH); but decreased with increasing temperature (Ta) and
Ψ1. WUEI consistently increased with the increase of PAR when PAR was below light saturation point. And it main-tained a constant when PAR excess light saturation point . The results showed that the influences of these factors were different and there were strong interactive effects of various microclimatic factors on WUEI. On clear days， the peak of WUEI was reached early after sunrise; it then decreased to a stable level maintained through most of the day until flling to zero at sunset. |