瞬时热胁迫对秋季3种植物叶片光系统Ⅱ活性和色素含量的影响

Effects of Transient Thermal Stress on Chlorophyll Fluorescence Parameters and Pigments Content in Leaves of Three Plants in Autumn

为研究秋季瞬时热胁迫对3种植物叶片光系统Ⅱ(PSⅡ)性能的影响,以日本晚樱、日本樱花、紫叶矮樱为试验材料,通过设置不同温度(25、30、33、36、39、42、45、48和51℃)及时间(5、25和45 min)组合处理,测定热胁迫后3种植物叶绿素荧光参数和色素含量。结果显示:同一温度下,随热胁迫时间的延长,3种植物初始荧光(F_(o))升高,最大荧光(F_(m))和PSⅡ最大光化学效率(F_(v)/F_(m))降低,单位反应中心吸收的光能(ABS/RC)、热耗散的光能(DI_(o)/RC)、捕获的用于还原Q_(A)的光能(TR_(o)/RC)增加,用于电子传递的能量(ET_(o)/RC)和用于电子传递的量子产额(φE_(o))等降低,用于热耗散的量子比率(φD_(o))增加。同一时间处理下,当热胁迫温度达到42~48℃,各荧光参数的变化情况与上述规律一致;温度和时间交叉处理下,各荧光参数随胁迫程度的增加呈现相同的规律;紫叶矮樱各项指标的变幅均显著小于日本晚樱和日本樱花,且ABS/RC、ET_(o)/RC、TR_(o)/RC和DI_(o)/RC的值最低、PSⅡ最大光化学效率最高,表明其受热胁迫的影响较小。随热胁迫程度增加,3种植物叶绿素总含量、花色素苷含量下降,叶绿素a/b增加,其中紫叶矮樱的变化幅度最小。因此,紫叶矮樱叶片的耐高温能力优于日本晚樱和日本樱花,其对热胁迫伤害的协调保护机制可能与花色素苷含量有关。

A plot experiment was conducted to examine the effects of transient thermal stress of different temperatures(25,30,33,36,39,42,45,48 and 51℃)and durations(5,25 and 45 min)on PSⅡperformance in autumn,and Cerasus serrulata,C.yedoensis and Prunus×cistena were used as experimental materials.The fluorescence characteristics,pigments content and physiological indexes of the three plants were determined after heat stress.The results showed that when the temperatures are same,with the increase of stress time,the initial fluorescence(F_(o))of three plants increased,the maximum fluorescence(F_(m))and PSⅡphotochemical efficiency(Fv/Fm)were reduced,the unit response center to absorb the light energy(ABS/RC),heat dissipation of light energy(DI_(o)/RC),which is used in the capture of the light energy reduction Q_(A)(TR_(o)/RC)increased,for the energy of the electron transfer(ET_(o)/RC)reduced.The quantum yield for electron transport(φE_(o))and_(o)thers were reduced,and the quantum ratio(φD_(o))for heat dissipation was increased.At the same time,when the temperature of heat stress reached 42~48℃,the fluorescence parameters changed in accordance with the above laws.Under the cross-treatment of temperature and time,the fluorescence parameters showed the same law with the increase of stress degree.The index variation of P.×cistena with rich anthocyanin was significantly lower than that of C.serrulata and C.yedoensis.P.×cistena was significantly lower in ABS/RC,ET_(o)/RC,TR_(o)/RC and DI_(o)/RC,and was highest in the maximum photochemical efficiency of PSⅡ,which indicated that the effect of heat stress_(o)n P.×cistena’s chlorophyll fluorescencecharacteristics of PSⅡwas less than that of C.serrulata and C.yedoensis.The concentration of chlorophyll and anthocyanin of the three plants decreased gradually with the increase of heat stress degree.While the ratio of chlorophyll a/b increased,and the variation of P.×cistena was the least.In summary,the capacity of high temperature tolerance of P.×cistena leaves is higher than that of C.serrulata and C.yedoensis,indicates the coordination protection mechanism of the P.×cistena against heat stress injury is related to the concentration of anthocyanin.