氮磷水平对细基江蓠氮、磷吸收及生长的影响

Effects of Nitrogen and Phosphorus Levels on Nitrogen and Phosphorus Absorption and Growth of Gracilaria tenuistipitata

关键词:  细基江蓠  氮  磷  相对生长速率  吸收速率  去除率

Key words:  Gracilaria tenuistipitata  nitrogen and phosphorus  relative growth rate  absorption rate  removal rate

摘要:

为了解氮（N）、磷（P）水平对细基江蓠（Gracilaria tenuistipitata）植物营养生理生态特征的影响，以亚热带大型海藻细基江蓠为原材料，研究不同N、P浓度条件下细基江蓠的生长，净化吸收N、P及其之间的相互关系。结果表明：细基江蓠的相对生长速率随着N、P浓度的增加而升高，但藻体增重幅度跟营养盐浓度不成正比，在N和P初始浓度分别为160 μmol·L^-1和10 μmol·L^-1时增幅最大，N、P水平和N/P明显影响细基江蓠的生长。在低N、P浓度条件下细基江蓠对N、P的去除率更高，P₄组（N=64 μmol·L^-1、P=4 μmol·L^-1）对PO₄^3--P去除率高达96.8%，对NH₄⁺-N和NO₃^--N的去除率也表现出类似特征。细基江蓠在高N/P组对P的去除率高，在低N/P组对N的去除率高，N、P胁迫对细基江蓠的营养盐去除率有明显影响。各实验组中细基江蓠对PO₄^3--P、NO₃^--N和NH₄⁺-N的吸收速率随着初始营养盐浓度的增加而升高，分别在PO₄^3--P初始浓度为25 μmol·L^-1，无机氮（NO₃^--N：NH₄⁺-N浓度比为1：1）初始浓度为200 μmol·L^-1时吸收速率最大。适应富营养环境的细基江蓠倾向于按Redfield比吸收N、P，偏离Redfield比则对细基江蓠的生长有明显的抑制效应。细基江蓠对N、P高去除率的特性使其成为富营养化水质修复的潜在优良种类。

Abstract:

In order to understand the effects of nitrogen (N) and phosphorus (P) levels on the nutritional, physiological and ecological characteristics of Gracilaria tenuistipitata, the subtropical macro-algae G.tenuistipitata was used as raw material to study the growth, purification and absorption of N, P and their relationship under different N and P concentrations. The results showed that the relative growth rate of G.tenuistipitata increased with the increase of N and P concentrations, but the gain range of algal weight was not proportional to the concentration of nutrient. The gain range was the largest when the initial concentrations of N and P was 160 μmol·L^-1 and 10 μmol·L^-1, respectively. N, P levels and the ratio of N/P significantly affected the growth of G.tenuistipitata. G.tenuistipitata had a higher removal rate when N and P concentrations were low. The removal rate for PO₄^3--P was as high as 96.8% in group P₄ (N=64 μmol·L^-1, P=4 μmol·L^-1). The removal rates of NH₄⁺-N and NO₃^--N also showed similar characteristics.The removal rate of P was high when N/P ratio was high, while the rate of N was high when N/P was low. Nutrient removal rate of G.tenuistipitata was significantly affected by N and P stress.The absorption rates of G.tenuistipitata to PO₄^3--P, NO₃^--N and NH₄⁺-N in each experimental group increased with the increase of initial nutrient concentration. The maximum absorption rate was obtained when the initial concentration of PO₄^3--P was 25 μmol·L^-1 and the initial concentration of inorganic nitrogen (NO₃^--N:NH₄⁺-N concentration ratio was 1:1) was 200 μmol·L^-1, respectively. G.tenuistipitata adapted to eutrophic environment tended to absorb N and P according to Redfield ratio, and deviation from Redfield ratio had obvious inhibitory effect on the growth of G.tenuistipitata. G.tenuistipitata may be potentially used for the restoration of eutrophic water quality due to their high removal rates of nitrogen and phosphorus.