Abstract: One-year-old Morus alba seedlings were cultivated in pots containing soil with different water contents to study the biomass, chlorophyll fluorescence parameters, net photosynthesis rate, stomatal conductance, transpiration rate and water use efficiency of the seedlings in response to diverse water stress. The results showed that the  aboveground biomass  and total biomass decreased with increasing water stress. However, more photosynthetic products were transferred to the roots in relation to the aboveground parts to make the root-shoot ratio increase. The fluorescence parameters, such as F_o, F_v and F_v/F_m, and stomatal conductance, transpiration rate and water use efficiency decreased with increasing water stress.

Key words: Morus alba, drought stress, biomass distribution, photosynthetic characteristics