干燥和模拟酸雨胁迫对条斑紫菜光合作用的影响

Photosynthesis Characteristics in Laver Porphyra yezoensis:Responses to Desiccation and Simulated Acid Rain

探讨了条斑紫菜在干燥和酸雨胁迫时叶绿体光系统Ⅱ最大光化学量子产量的变化。试验结果表明,条斑紫菜在干燥3 h后脱水94.5%,光合作用停止,复水后迅速恢复其原有的光合能力。刚脱水的条斑紫菜在未干燥时如遭遇酸雨,其最大光化学量子产量随pH降低和时间延长而降低。试验中最低的pH 4.0酸雨处理6 h后,复水6 h仍能恢复光合能力。如干燥脱水后遭遇酸雨,除pH 5.6处理1h组经过24 h恢复,可基本达到原有的光合能力外,pH 4.5组24 h内不能恢复。而pH 4.0组藻体变红死亡。如干燥后酸雨处理3 h,pH 5.6和pH 4.5组均受到严重伤害,而在24 h内不能恢复正常光合能力,pH 4.0组趋于死亡。说明干燥脱水和酸雨的双重胁迫,严重危害条斑紫菜的生存,可能造成条斑紫菜养殖的严重减产。

The changes in the optimum photochemical quantum yield（Fv/Fm）of photosystem 11 were investigated in laver Porphyra yezoensis exposed to desiccation and simulated acid rain stresses, sometimes occurrence under natural conditions. The results showed that the thalli lost 94.5 % of water 3 hours after the desiccation, and then stopped photosynthesis, but resumed photosynthesis quickly during immersion in sea water. The maximum quantum yield was found to decrease as the pH decreased and the period prolonged when the thalli just undesiccated exposed to acid rain. The thalli had recovery photosynthetic capacity 6 hours after rehydration when the thalli were exposed to the minimal pH（4.0）acid rain for even 6 hours. However,the thalli did not show recovery photosynthesis when they were exposed to pH 4.5 medium except in the thalli exposed to pH 5.6 for 24 hours,even turned to red and died in the pH 4.0 medium. The thalli were heavily damaged and did not recover photosynthetic capacity 24 hours after the thalli were exposed to acid rain for 3 hours after desiccation in the pH 5.6 and pH 4.5 groups,even died in the pH 4.0 group. The results suggested that the double stresses of desiccation and acid rain lead to decrease in the survival and production of the laver.