Photosynthetic physiology responses of two Potentilla species under drought stress

The ultra-structure and photosynthetic physiology of Potentilla leucophylla and P.verticillaris under different dehydrate stresses were studied with electron microscopy. Under light dehydrate stress, the ultra-structure of two P.species had minor damage. The photosynthetic indices including stomatal conductance (Gs), net photosynthetic rate(Pn), transpiration rate(Tr), intercellular CO2 concentration(Ci) and water use efficiency (WUE) also decreased, especially Gs decreased significantly which showed that stomatal limited photosynthesis. Under moderate and severe dehydrate stresses, the ultra-structure of two P.species had serious damage; simultaneously. The photosynthetic indices had different performance. Pn decreased further, Tr,Gs and WUE decreased rapidly and Ci increased slowly. Non-stomatal limitation played a major role in this progress. Both Potentilla species have drought resistance based on the the structural and physiological indices although P.verticillaris had slightly stronger drought tolerance than P.leucophylla.