A Preliminary Study on NH₄⁺-N Uptake Kinetics of Potamogeton malaianus under Different Nutrient Conditions

The effects of the different nutrient conditions(low:TN 0.213 mg· L^-1,TP 0.0093 mg·L^-1;middle:TN 0.71 mg·L^-1,TP 0.031 mg·L^-1;high:TN 7.1 mg·L^-1,TP 0.31 mg·L^-1) on the growth and NH+4-N uptake kinetics of Potamogeton malaianus axenic seedlings were studied in hydroponic culture in the laboratory.It is showed that plant biomass was not significantly affected by different levels of nutrition after two months culture.The maximum absorb velocity of the plant(V_max) showed significant difference among different nutrient culture,ranging from 41.1 μmol·g^-1·h^-1(high nutrient condition) to 29.1 μmol·g^-1·h^-1(middle nutrient condition) and 21.1 μmol·g^-1·h^-1(low nutrient condition).The Michaelis constant(K_m) also showed significant difference among different nutrient culture,with values from 0.356(high nutrient condition) to 0.306(middle nutrient condition) and 0.122 mmol·L^-1(low nutrient condition).The results showed that NH₄⁺-N uptake kinetics of P.malaianus were closely related with its surrounding environment.This plant acclimates to low nutrient availability by increasing the affinity for nutrient uptake and conversely to high nutrient availability by increasing its uptake capacity.