盐度对羊栖菜(Sargassum fusiforme)幼体光合特性的影响

以羊栖菜(Sargassum fusiforme)幼体为实验材料,设置不同海水盐度(15‰、20‰、29‰、45‰),对羊栖菜幼体进行梯度胁迫处理,探讨不同盐度胁迫对羊栖菜幼体光合作用的影响。结果表明,在盐胁迫条件下,羊栖菜的光合作用会受到明显影响。在盐度20‰条件下,羊栖菜幼体光合作用受到的抑制作用较弱,羊栖菜幼体对低盐度海水有一定的耐受性。海水盐度过低(15‰)时,羊栖菜光合作用受到明显抑制。高盐(45‰)条件下,羊栖菜幼体受到损伤,羊栖菜幼体光合作用和无机碳利用受到显著抑制。短时间(1~12 h)处理,羊栖菜光合作用受到的影响较小,各盐度处理的羊栖菜幼体色素含量、最大相对电子传递速率(rETR_max)、最大光化学量子产量(F_v/F_m)出现先降低后升高的趋势。长时间(240 h)处理,盐度过低(15‰)或过高(45‰)均会抑制羊栖菜幼体的光合作用,其rETR_max、光能利用效率(α)、最大净光合作用速率(P_nmax)、最大光合固碳速率(v_max)均显著降低,而且过高盐度通过阻碍羊栖菜幼体光合色素合成影响其光合作用过程。实际生产中,当产生过高或过低盐度变化时,应当及时做好羊栖菜的防低盐或高盐胁迫处理,防止长时间的盐度变化影响羊栖菜特别是其幼体的生长。

Effects of salinity level on photosynthetic characteristics of Sargassum fusiforme seedlings

Sargassum fusiforme seedlings were used to determine their photosynthetic responses to different seawater salinities (15‰, 20‰, 29‰, 45‰). The results showed that photosynthesis of S. fusiforme was significantly affected by excessive low-and high-salinity stress. Specifically, at salinity of 20‰, photosynthesis of S. fusiforme seedling was slightly affected, which indicated low salinity tolerance in S. fusiforme seedlings. However, excessive low salinity level (15‰) significantly depressed algal photosynthesis. At high salinity of 45‰, S. fusiforme seedlings were damaged by high salt stress, its photosynthetic activity and utilization of inorganic carbon were significantly inhibited. In a short time treatment(1-12 h), seedling photosynthesis was slightly affected, and it's pigment contents, maximum relative election transport rate (rETR_max), and maximal photochemical efficiency (F_v/F_m) exhibited changes of decreasing followed by increase. In prolonged culture(240 h), excessive low-(15‰) or high-salinity (45‰) significantly inhibited algal photosynthesis, meaning notable decreasing of its rETR_max, light use efficiency(α), maximum net photosynthesis rate (P_nmax) and photosynthetic carbon fixation (v_max). Moreover, excessive high salinity stressed the photosynthesis process of S. fusiforme seedling by hindering the synthesis of its photosynthetic pigments. It indicated that the strategies for preventing low-and high-salinity stress on S. fusiforme seedlings should be practically performed when the salinity level extremely changed, to avoid the severe stress of prolonged salinity change on the seedlings.