大气CO2浓度和温度变化对石莼生长及其叶绿素荧光特性的影响

Effect of CO2 and Temperature Change on the Growth and Chlorophyll Fluorescence in Ulva lactuca

关键词:  石莼  CO₂  温度  生长  生化组分  叶绿素荧光

Key words:  U.lactuca  CO₂  temperature  growth  biochemical composition  chlorophyll fluorescence

摘要:

[目的]为了研究大型海藻在全球气候变化背景下的生态功能,探讨大气CO₂浓度升高和温度变化对石莼(Ulva lactuca)生长及其叶绿素荧光特性的影响。[方法]在4种条件(390 μL/L CO₂+15℃;700 μL/L CO₂+15℃;390 μL/L CO₂+25℃;700 μL/L CO₂+25℃)下培养石莼,10 d后测定藻体生长、叶绿素荧光参数以及生化组分。[结果]经10℃低温6 h处理,石莼受到光抑制;经35℃高温6 h处理,25℃正常空气条件下生长的石莼表现出较高的最大光量子产量(Fv/Fm),光能利用效率(α),非光化学淬灭(NPQ)和光化学淬灭(qP),25℃高CO₂浓度条件下生长的石莼最大相对电子传递速率(rETR_max)和饱和电子传递速率(Ek)大于其他生长条件下的石莼;经40℃高温处理6 h,15℃生长的石莼光合机构受损;相对于25℃与正常空气条件下生长的石莼,25℃与高CO₂浓度条件下生长的石莼Fv/Fm、a、NPQ和qP的下降程度较小,而且具有较高的rETR_max和Ek。[结论]高CO₂浓度促进石莼的生长,但其对石莼可溶性蛋白(SP)、可溶性碳水化合物(SC)、叶绿素a(Chl a)和类胡萝卜素(Car)等生化组分含量影响具有温度依赖性。另外,CO₂浓度升高使得石莼抗高温的能力增强。

Abstract:

[Objective] The effects of CO₂ concentration and temperature on the growth and chlorophyll fluorescence of Ulva lactuca were investigated.[Methods] Ulva lactuca was cultured under the following four different conditions:(1) 390 μL/L CO₂ + 15℃; (2)700 μL/L CO₂ + 15℃; (3) 390 μL/L CO₂ + 25℃;and (4) 700 μL/L CO₂ + 25℃.After cultured for 10 d, the growth, chlorophyll fluorescence and biochemical compositions were examined.[Results] The results showed that elevated CO₂ enhanced the growth of U.lactuca.The effects of CO₂ on soluble protein (SP), soluble carbohydrate (SC), chlorophyll a (Chl a) and carotenoid (Car) were temperature-dependent.After exposed to 10℃ for 6 h, photoinhibition occurred in U.lactuca.After exposed to 35℃ for 6 h, 25℃ and normal air-grown algae displayed highest optimal photochemical quantum yield (Fv/Fm), photosynthetic light use efficiency (α) and non-photochemical quenching (NPQ);while 25℃ and high CO₂-grown algae exhibited highest maximum relative electron transport rate (rETR_max) and light saturation point (Ek).After exposed to 40℃ for 6 h, photosynthetic apparatus of 15℃-grown algae were seriously destroyed; For 25℃ growth condition, high CO₂-grown algae displayed lower decline degree in Fv/Fm, a, NPQ and photochemical quenching (qP) compared to normal air-grown.[Conclusion] Our results suggested that elevated CO₂ improved heat endurance in U.lactuca.