Photosynthetic Physiological Adaptabilities of Robinia Pseudoacacia Clones under Drought Stress

Photosynthetic physiological adaptabilities of four Robinia pseudoacacia clones under drought stress were studied by pot cultivation.The result showed that net photosynthetic rate of the four clones decreased under gradual drought stress of soil with different adaptive modes.W1 and L1 were sensitive to drought stress.Their stomatal conductance and transpiration rate decreased and water use efficiency increased at early stage of drought stress,which indicated stronger water availability.However,stomatal conductance of L59 and L78 decreased at late stage of gradual stress and the reduction of transpiration rate was small.But they had higher net photosynthetic rate,showed higher photosynthetic capacity.