Under water stress,maximum photochemical efficiency( F v / F m) value and chl content decline ,basal rates of chl fluorescence( F 0) value ascend,photosynthetic organ was damaged;

• 水分胁迫下，六种参试树种叶片的最大荧光效率下降，初始荧光上升，叶绿素含量下降，光合机构受到破坏；