不同温度和胁迫时长下蓝云杉的光合响应

Thermal Stress Photosynthetic Response of Picea pungens

[目的]全球气候持续变暖将不利于蓝云杉生长,研究蓝云杉在高温胁迫下的生长、光合响应机制,为蓝云杉引种栽培提供参考。[方法]以五年生蓝云杉苗为试验材料,设定45、50、55℃3种温度,处理6 h;其中45℃处理还有12、18、和24 h不同时长,常温(25℃)作为对照。研究处理后、恢复7和28 d的生长表型、针叶含水量和叶绿素荧光参数,分析高温、胁迫时长对蓝云杉生长和光合作用的影响。[结果]45℃处理6 h蓝云杉基本可以恢复正常生长,而50℃和55℃处理的蓝云杉整株针叶都变黄,干枯掉落,伴随着相对含水量的降低,且光系统Ⅰ(PSⅠ)有效量子产量实际光化学效率(Y(Ⅰ))、PSⅠ相对电子传递速率(ETR(Ⅰ))、由供体侧限制引起的PSI处非光化学能量耗散的量子产量(Y(ND))、受体侧非光化学能量耗散产生的量子产量(Y(NA))、光系统Ⅱ(PSⅡ)有效量子产量实际光化学效率(Y(Ⅱ))、PSⅡ相对电子传递速率(ETR(Ⅱ))、PSⅡ的最大光化学效率(F_(v)/F_(m))和用于电子传递的量子产额(φE_(o))均显著低于45℃处理和对照。尽管45℃处理6、12、18、24 h后从表型上看不出蓝云杉的形态发生明显变化,但是恢复期发现12、18 h针叶继续失水、变黄,24 h处理整株针叶都变黄,基本干枯掉落,针叶相对含水量降至最低。恢复28 d时,18、24 h的荧光参数φE_(o)几乎为0,电子传递受到了抑制。[结论]胁迫时长为6 h,蓝云杉可以耐45℃高温处理,不耐50、55℃高温。45℃高温处理时长超过12 h苗木失水严重,针叶干枯,对光合特性产生了显著影响,难恢复正常生长。

[Objective]The continuous global warming will be detrimental to the growth of Picea pungens.Studying the growth and photosynthetic response mechanism under high temperature stress would provide a reference for the introduction and cultivation of P.pungens.[Methods]Three temperatures were set at 45,50 and 55℃,and treated for 6 hours using P.pungens seedlings.Among them,three different durations of 12,18 and 24 hours were also set under 45℃ treatment,and room temperature was used as a control.The growth phenotype,relative water content and chlorophyll fluorescence parameters of P.pungens seedlings after treatment,7 and 28 days of recovery were studied,and the effects of high temperature and stress duration on the growth and photosynthesis of P.pungens were analyzed.[Result]The growth of P.pungens could basically be restored after 6 hours treatment at 45℃,while those treated at 50 and 55℃,their needles turned yellow,withers and falls,accompanied by the decrease of relative water content.The fluorescence parameters photochemical efficiency for photosystem Ⅰ(Y(Ⅰ)),relative electron transfer rate of photosystem Ⅰ(ETR(Ⅰ)),non-photochemical energy dissipation due to donor-side restriction(Y(ND)),non-photochemical energy dissipation due to receptor-side restriction(Y(NA)),photochemical efficiency for photosystem Ⅱ(Y(Ⅱ)),the relative electron transfer rate of photosystem Ⅱ(ETR(Ⅱ)),PSⅡ maximum light energy conversion efficiency(Fv/Fm)and the maximum quantum yield of electron transport between PSⅡ and PSI(φE_(O))were significantly lower than those treated and controlled at 45℃.Although the phenotypic change could not be seen after treatment at 45℃ for 6,12,18 and 24 hours,it was found that the needles continued to lose water and turn yellow at 12 hours and 18 hours during the recovery period,and the whole needles turned yellow after 24 hours treatment,basically dried up and fell off,and the relative water content of the needles was the lowest.When recovering for 28 days,φE_(o) at 18 and 24 hours was almost 0.[Conclusion]P.pungens can withstand high temperature treatment at 45℃ for 6 h,but it is not resistant to high temperature of 50℃ and 55℃.The seedlings with a high temperature treatment time of 45℃ for more than 12 hours will suffer severe water loss and dry needles,which will have a significant impact on the photosynthetic characteristics and make it difficult to resume normal growth.