Photosynthetic characteristics of different walnut varieties

In order to investigate photosynthetic capacity of main walnut varieties in Xinjiang,taking eight main walnut varieties in Xinjiang as materials,diurnal changes of photosynthetic parameters of the varieties were investigated by using portable photosynthesis system Li-6400.The results show that the values of net photosynthetic rate,stomatal conductance and transpiration rate of Zha 343 and 609 are significant higher than that of the other varieties,and all of the photosynthetic parameters of Xinfeng and 917 are significant lower than that of the other varieties.The stomatal conductance and transpiration rate are positively correlated to net photosynthetic rate,and intercellular concentration of CO2 is negatively correlated to net photosynthetic rate.The diurnal variation curves of net photosynthetic rate,stomatal conductance and transpiration rate of the varieties are double peaks,but the diurnal variation curve of intercellular concentration of CO2 is double valleys.The midday depression of photosynthesis is caused by stomatal and non-stomatal limitation.