温度对不同生长时期鼠尾藻生长及光合作用的影响

Effect of temperature on growth and photosynthetic activity of Sargassum thunbergii

以不同生长时期(发芽期、缓慢生长期、快速生长期、成熟期、衰败期)的鼠尾藻(Sargassum thunbergii)为实验材料,通过测定其在不同温度(10~30℃)下的鲜重和长度的相对生长率(反映生长速度)、鲜重/长度比(反映生长策略)、叶绿素含量(反映生长状态)、表观光合速率(反映光合作用的强弱)和呼吸速率等指标,以揭示不同生长时期的鼠尾藻对不同温度的生理生态适应性。结果表明,不同生长时期的鼠尾藻对温度响应的生长策略不同。温度15℃下鼠尾藻光合速率达到最大值,呼吸速率最低,从而促进鼠尾藻幼体萌发;缓慢生长期和快速生长期的鼠尾藻最适生长温度范围为15~25℃,并在此温度范围内,鼠尾藻的相对生长率随着温度的升高而升高。成熟期藻体在受试温度范围内的色素含量和相对生长率均高于其他时期,并且在25℃时的相对生长率与色素含量达到峰值。衰败期鼠尾藻的相对生长率一直为负值,色素含量呈现先上升后下降趋势,呼吸速率显著高于其他生长时期。由上述结果可知,不同生长阶段的鼠尾藻表现出不同的温度适应性,快速生长期的鼠尾藻对温度变化的适应能力较强。本研究丰富了鼠尾藻自然种群的生理生态学基础研究,也可为鼠尾藻藻场建设中对其生长阶段的选择及藻种投放海域的选择等提供科学依据。

We investigated the effect of temperature(10℃,15℃,20℃,25℃and 30℃)on the growth and photosynthetic activity of Sargassum thunbergii at different growth staged(germination,slow growth,rapid growth,maturity and declining).The results showed that the growth strategy of S.thunbergii was different among growth stages.At 15℃,the germination of S.thunbergii was promoted.The optional growth of S.thunbergii at slow and rapid growth stages was observed when temperature varied between 15 and 25℃,within this range,the growth rate of S.thunbergii increased with temperature.The pigment content and specific growth rate in S.thunbergii at mature stage were higher than those at other growth stages,which reached the highest at 25℃.S.thunbergii at declining stage started to fade,during which its pigment content increased first than declined with temperature.It conducted low photosynthesis at 30℃.At maturity,S.thunbergii pigment content and specific growth were higher than those at other stages and at all tested temperature points,both were the peaks.At the decaying stage,S.thunbergii started to fade;the pigment content declined following an increase first and the high temperature(30℃)led to a relatively low photosynthesis.Our findings enriched the basic information of S.thunbergii,and provided a scientific basis for the protection of S.thunbergii resource.