Effects of Cu~(2+) on physiological properties and photosynthesis of Hydrocharis dubia (Bl.)

Hydrocharis dubia( Bl.) grown in a 1 /2 Hoagland growth medium with different Cu2 +concentrations was studied to investigate the effects of Cu2 +on the biomass gain and photosynthesis of Hydrocharis dubia( Bl.).The amounts of chlorophyll,chlorophyll a / b,net photosynthetic rate,stomatal conductance,intercellular CO2concentration,and transpiration rate were also investigated. The results show that the biomass gain decreased with the increase of the Cu2 +concentration and a biomass decrease occurred in Hydrocharis dubia( Bl.) grown in the medium with ρ( Cu2 +) = 5. 0 mg/L. The amounts of chlorophyll decreased with the increase of the Cu2 +concentration as well,indicating that the synthesis of chlorophyll was impaired by Cu2 +due to the effects of Cu2 +on the growth of Hydrocharis dubia( Bl.),which resulted in the decrease of the net photosynthetic rate and stomatal conductance.