充气培养对半叶马尾藻生长﹑营养盐吸收和生化组成的影响

Effects of aerated culture on growth, nutrient uptake, and biochemical composition in Sargassum hemiphyllum

将半叶马尾藻(Sargassum hemiphyllum)置于实验室球形培养瓶内培养15 d,设置5个充气速率(50 m L/min、100 m L/min、200 m L/min、400 m L/min和800 m L/min)为实验组,静水培养(0)为对照组。每隔5 d测定藻体的生长速率和营养盐吸收速率,培养实验结束时,测定藻体的色素含量、可溶性蛋白和可溶性糖含量。结果表明:充气速率和培养时间均对半叶马尾藻的生长和PO34--P的吸收具有显著影响,而对NO3--N来说,仅培养时间对其吸收影响显著。培养第1天时,充气可显著促进营养盐吸收,最大充气速率(800 m L/min)培养的半叶马尾藻对NO3--N和PO34--P的吸收速率分别比静水培养的马尾藻高133.77%和89.51%,生长速率也比静水培养的马尾藻高95.04%。随着培养时间的延长,充气速率对半叶马尾藻的生长和营养盐吸收的促进作用逐渐减弱。在培养第15天时,充气速率为800 m L/min条件下的半叶马尾藻对NO3--N的吸收速率比静水培养的马尾藻低24.87%,对PO34--P的吸收速率仅高出静水培养下的46.03%,而生长比静水培养的马尾藻高出75.16%。同时,除了可溶性蛋白含量,高充气速率可抑制叶绿素a(Chla)、类胡萝卜素(Car)和可溶性糖合成。因此,水体运动是通过对营养盐吸收及其他生理过程产生的作用间接影响半叶马尾藻的生长,而不是直接影响半叶马尾藻生长和产量的最重要因素。

We evaluated the effects of aeration rate（0, 50 m L/min, 100 m L/min, 200 m L/min, 400 m L/min, 800 m L/min） on the growth and nutrient uptake rates of the thalli of the brown alga Sargassum hemiphyllum. The thalli were incubated in the laboratory for 15 d and were measured every 5 d. additionally, the pigment content and concentration of soluble proteins and soluble sugar in thalli were measured at the end of the experiment. Both aeration rate and culture time significantly influenced the relative growth rate（RGR） and PO43--P uptake rate of S. hemiphyllum, but only culture time had a significant effect on the rate of NO3--N uptake. On the first day, aeration rate had a significant effect on the nutrient uptake rate. At the highest aeration rate we tested（800 m L/min）, NO3--N and PO43--P uptake rates were 133.77% and 89.51% higher, respectively, than in the control（0）, and RGR was also 95.04% higher than in the control. However, the positive impact of aeration rate on thalli growth rate and nutrient uptake rate decreased as culture time increased. At the highest aeration rate, the NO3--N uptake rate was 24.87% lower than in the control at the end of the experiment and the PO43--P uptake rate was 46.03% higher than in the control. Conversely, the RGR of thalli was 75.16% higher than in the control at this time. High aeration rates appeared to inhibit the synthesis of chlorophyll a, carotenoids, and soluble sugars, but significantly promote soluble proteins synthesis. Our results suggest that water movement does not exert a direct effect on thalli growth and biomass, but rather an indirect effect induced by changes in nutrient uptake and other physiological processes.