底栖铜藻和漂浮铜藻生长与光合生理的比较

铜藻是构成"金潮"的关键种。为了探索"金潮"的爆发原因,采集同一位点的底栖和漂浮铜藻,在温度15℃、光照强度5000 lx条件下,经过7天培养后,比较了两类铜藻生长速率和各组织部位(新生叶、老叶、气囊、枝干)生长以及光合生理的差异。结果表明:漂浮铜藻的生长速率(RGR)为8.25%·d(-1),而底栖铜藻的RGR仅为5.79%·d^-1;底栖铜藻叶片(老叶和新生叶)的光合色素含量显著高于漂浮铜藻的叶片;而漂浮铜藻的非光化学淬灭(NPQ)和调节性能量耗散的量子产量Y(NPQ)]值显著高于底栖铜藻;相较于其他组织部位(老叶、气囊、枝干),新生叶在强光下拥有更高的最大相对电子传递速率(r ETRmax)和饱和光强(Ik);底栖和漂浮铜藻的生理特性存在明显的差异,漂浮铜藻具有更高的生长能力,热耗散能力更强,新生叶片在强光下耐受能力更强,表明漂浮铜藻更适宜在海面环境生活。

Comparative analysis of growth and photosynthetic characteristics in benthic and floating Sargassum horneri

Sargassum horneri is a key species in "golden tide". In order to explore the reason of"golden tide",we collected floating and benthic S. horneri at same site,and cultured at 15 ℃and 5000 lx for 7 days,and then compared the growth rates and photosynthetic characters between the two types of S. horneri. The results showed that the relative growth rate( RGR) of floating S. horneri was 8.25%·d^-1,while that of benthic S. horneri was only 5.79%·d^-1. The photosynthetic pigment contents in leaves( old and newborn leaves) of benthic S. horneri were higher than that of floating S. horneri. Floating S. horneri had higher NPQ and Y( NPQ) values than benthic ones. Newborn leaves of both species types had higher maximum relative electron transfer rate( r ETRmax) and saturation light intensity( Ik) than other tissues( old leaf,vesicle,and stem). These results indicated that there were significant differences in physiological characteristics between benthic and floating S. horneri. Floating S. horneri had better growth ability and stronger heat dissipation ability. Newborn leave had stronger tolerance under high light. Our results suggest that the floating type was more suitable to sea surface environment.