Relationships of photosynthesis and transpiration of Populus euphratica with their affecting factors

In this research we studied correlations between the photosynthetic and transpiration rate of Populus euphratica and their affecting factors.Results showed that photosynthetic rate was logarithmically related to stomatal conductance;The relation between transpiration rate and stomatal conductance was lineal.They both polynomially associated with photosynthetically active radiation,and binomially with air temperature.There also indicated that P.euphratica belonged to the plants limited by stomata.Stomatal conductance and photosynthetically active radiation commonly decided the magnitude of photosynthetic and transpiration rate.Air temperature and relative humanity affected them by means of stomatal conductance.The conditions that P.euphratica adapt to photosynthetic gas exchange were that photosynthetically active radiation kept about 1700μmol·m-2·s-1,temperature was nearly 35℃ and relative humanity was 20%-30% or so.