光、氮和半连续培养更新率对微绿球藻生长与采收量的影响

Effects of light intensity,concentration of nitrogen and renewal rate in semicontinuous cultures on growth and recovery yield of Nannochloropsis oculata (Droop) Hibberd

对水产养殖中的主要饵料微绿球藻(Nannochloropsisoculata(Droop)Hibberd)进行了5×3×2析因试验,培养液NO-3-N水平分别设置为0、3、6、12、24mg/L,光照强度分别为22.9μmol/(m2·s)、43.2μmol/(m2·s)、80.4μmol/(m2·s),更新率分别为10%和25%,研究了光、氮和半连续培养更新率对微绿球藻生长、采收量的影响。协方差分析结果显示,NO-3-N水平、光照强度、更新率及其交互作用对细胞密度、生长率和采收量的影响均存在显著差异(P<0.001),以更新率影响最大,其次是光照强度,影响最弱为NO-3-N水平。更新率25%时,平均细胞密度(753.2×104/mL)显著低于10%更新率下的细胞密度(1737.5×104/mL),但平均生长率和采收量都显著高于更新率10%时的生长率和采收量,分别为0.349/d和4.69×108/d。在光照强度22.9μmol/(m2·s)下,细胞密度、生长率和采收量都显著低于其他组,其最大值均在80.4μmol/(m2·s)光照强度组,该组细胞密度、生长率和采收量分别为1721.1×104/mL、0.283/d和6.51/×108/d。在不同NO-3-N水平处理下,不添加NO-3-N时的细胞密度、生长率和采收量都最低,3mg/L时次之,6mg/L以上组(包括6mg/L组)最高。研究结果还表明,更新率增加时,不仅光衰减变小,生长率随之变大,而且培养液中NO-3-N浓度也随之增加,从而促进?

A 5×3×2 factorial experiment was designed with five concentrations of nitrogen (0, 3, 6, 12 and 24 mg/L in the form of NO^-_3-N), three light intensities and two renewal rates (10% and 25%) to determine the effects of light intensity,concentration of nitrogen and renewal rate in semicontinuous cultures on the growth and recovery yield of Nannochloropsis oculataBZ(Droop) Hibberd. N.oculata, rich in EPA, is one of the main feed source of aquatic animals in aquaculture. The results of GLM ANCOVA show that concentration of nitrogen, light intensity, renewal rate and their interactions have significant effects on cell density, growth rate and recovery yield (P <(0.001)) of N.oculata , and the most affecting factor is renewal rate, and follows the light intensity and concentration of nitrogen. With the renewal rate of 25%, the average cell density (753.2×10~4/mL) was lower than that with renewal rate of 10%, which was 1 737.5×10~4/mL, but mean growth rate and recovery yield were greater than the latter′s, which were 0.349/d and 4.69×10~8/d, respectively. Under the light intensity of 22.9 μmol/(m^2·s), cell density, growth rate and recovery yield were significantly lower than any other group of light intensity, and their maxima values, which were 1 721.1×10~4/mL, 0.283/d and 6.51×10~8 /d, respectively, were obtained only with light intensity of 80.4μmol/(m^2·s). In different treatments of nitrogen concentrations, the significantly different contributions of nitrogen concentration to cell density, growth rate and recovery yield from low to high were 0 mg/L, 3 mg/L and 6 mg/L. The results also indicate that increasing renewal rate not only promotes growth rate because of light attenuation reduction, but also enhances recovery yield because of increasing the concentration of nitrogen, and meanwhile, improving the balanced utilization between light and nitrogen. But it is noted that cell density decreases with increasing renewal rate. Obviously, the renewal rate was major factor influencing recovery yield, and furthermore, an optimal renewal rate causing maximum recovery yield was also existence. Thus, these results have interesting applications for the management of reasonable renewal and scientific nitrogen application in semicontinuous cultures.