Effects of nitrogen input and inundation on photosynthetic characteristics of Cyperus malaccensis of the Min River estuary:A mesocosm experiment
Exogenous nitrogen (N) enrichment resulting from human activity,can strongly influence the estuarine ecosystems.In this study,using mesocosm method,we examined the effects of nitrogen input (0,8 and 16 g· m-2· a-1) and inundation degree (short-time inundation and moderateinundation) on the growth and photosynthetic characteristics of Cyperus malaccensis in the Min River estuarine wetland.The ground and underground biomass of C.malaccensis in short-time inundation treatments were significantly greater than that of moderate-inundation after six months of experiments (p＜ 0.05).The biomass and fixation of photosynthetic carbon in C.malaccensis increased significantly after nitrogen input,mainly due to the increase of light saturation point (LSP) and relative chlorophyll content (SPAD),and the drop of dark respiration rate(Rd).Diurnal variation of net photosynthetic rate (Pn) opposited to the variation of the intercellular CO2 concentrations (Ci) in the growth period.Diurnal variation of Pn presented a single-peaked curve at all the period of crop-rotation of C.malaccensis in short-time inundation treatment,but also appeared a typical bimodal curve in accompany with the obvious midday depression of photosynthesis in the moderate-inundation treatment after fifteen months.We also found that the non-stomatal factors were the most important photosynthetic and physiological controlling factors for the increasing of diurnal mean values of Pn in nitrogen input addition treatment.
nitrogen inputwater inundationphotosynthetic characteristicsCyperus malaccensisMin River estuary
NETL
NSTL
万方数据
维普
