附着物对菹草光合作用速率的抑制效应

Inhibition Effects of Epiphyte on Photosynthesis Rate of Potamogeton crispus

2012年5月对白洋淀不同营养水平的8个区域进行现场调查,研究了菹草(Potamogeton crispus)附着物的生物量(以w计)与营养盐水平的关系及其对菹草光合作用速率的影响.结果表明,随着ρ(TN)、ρ(TP)的增加,菹草上附着物的生物量、w(Chla)和净初级生产力逐渐升高,在营养盐水平较高的王家寨〔ρ(TN)为6.074 mg/L,ρ(TP)为0.161 mg/L〕达到高峰,附着物的生物量为0.073～0.384 mg/g,w(Chla)为0.019～0.112 mg/g,净初级生产力为0.007～0.154 mg/(g·h).附着物对菹草的光合作用速率产生明显的抑制作用,并且随着附着物生物量的增加,抑制作用明显增强,在营养水平较高的王家寨,抑制率可达72%;南刘庄和端村次之,抑制率分别为64%和55%;而在营养水平较低的光淀,抑制率仅为11%.初步推测附着物对菹草的光合作用的影响可能源于附着物的遮荫作用.

Epiphyte is commonly involved in the material transformation of water ecological system, and plays an important role in the shift between maerophyte-dominated and algal-dominated lake ecosystems. In order to study the inhibition effect of epiphyte on photosynthesis rate of the plant and the relationship between epiphyte biomass （w） and nitrogen and phosphorus level, the biomass and net primary production of epiphyte attached on submerged macrophyte Potamogeton crispus collected from 8 sampling were studied in Baiyangdian Lake in May of 2012. The results showed that the biomass, the chlorophyll-a （Chla） content and primary production of epiphyte were positively associated with concentrations of nitrogen and phosphorus. The maximum values were found at the site of Wangjiazhai, where concentrations of nitrogen and phosphorus were 6. 074 mg/L（TN） and 0. 161 mg/L（TP） respectively, and the biomass, Chla content and primary production of epiphyte were 0. 073-0. 384, 0. 019-0. 112 mg/g and 0. 007-0. 154 mg/（ g. h） , respectively. The photosynthesis efficiency of P. crispus was significantly inhibited by the epiphyte, and the maximum inhibition rate was up to 72% at Wangjiazhai, followed by Nanliuzhuang and Duancun with inhibition rates of 64% and 55% respectively. However, the photosynthesis rate of P. crispus only decreased by 11% with a low nutritional level at Guangdian. The shading effect of epiphyte might affect the growth of P. crispus. It could be concluded that epiphytie community is an important component for aquatic ecosystems and the primary production of epiphyte was significantly affected by concentrations of nitrogen and phosphorus. This study would provide a basic information on the recession of submerged vegetation in the eutrophieated water.