不同氮磷水平下中肋骨条藻对营养盐的吸收及光合特性

PHOTOSYNTHETIC CHARACTERISTICS AND NUTRIENT ABSORPTIN OF SKELETONEMA COSTATUM AT DIFFERENT NITROGEN AND PHOSPHORUS LEVELS

研究了不同氮、磷水平下中肋骨条藻 (Skeletonemacostatum)对营养盐的吸收动力学、生长和光合作用特性 .结果表明 ,培养基中氮或磷浓度的改变对中肋骨条藻比生长速率影响不大 ,各种条件下藻细胞的比生长速率约为1.5 1～ 1.6 0d-1,其中 ,藻细胞在低氮条件下的比生长速率略高 ,为 1.6 0d-1;低氮和低磷条件下藻细胞稳定期的生物量明显下降 ,分别比中氮和高氮下减少了 2 7%和 4 1% ,而比中磷和高磷减少了 6 4 %和 6 5 % .低营养源 (低氮或低磷 )状态下生长的藻细胞具有较低的单位细胞表示的光饱和的光合作用速率 (Pcellm )和光合效率 (αcell) .尽管在低氮或低磷条件下生长的藻细胞单位叶绿素a的含量较低 ,但具有较高的活性 ,以单位叶绿素a表示的光饱和的光合作用速率 (Pchlam )和光合效率 (αchla)均与高氮或高磷条件下生长的藻细胞相当 ,这可能是不同氮、磷水平下比生长速率差异不大的原因 .中肋骨条藻细胞对氮和磷吸收的适当比值 (N/P)为 0 .8～ 2 .6 .图 3表 4参

The uptake of nitrogen and phosphorus by Skeletonema costatum, and growth and photosynthesis characteristics of the alga were studied in laboratory batch cultures. The results indicated that the specific growth rate (ranging between 1.51～1.60 d -1) did not vary very much with different nitrate and phosphate concentrations in our experiment, while it was a little higher at low nitrate level; the maximum yield was much lower at middle nitrate and low phosphate level, which decreased by 27% and 41%, respectively compared with low nitrate and high nitrate, and by 64% and 65% compared with middle phosphate and high phosphate. The cells cultured at lower nutrient level showed lower cell-specific light-saturated photosynthetic rate (P cell m) and apparent photosynthetic efficiency (α cell). The cells grown in low nitrate or low phosphate medium were more active and their chlorophyll a-specific light-saturated photosynthetic rate (P chl a m) and apparent photosynthetic efficiency (α chl a) were comparable with those of the cells grown at high nitrate or high phosphate, which was probably the reason that the differences in specific growth rates under all conditions were not obvious. The ratios of uptake rates of nitrate and phosphate by Skeletonema costatum ranged between 0.8～2.6. Fig 3, Tab 4, Ref 17