低温胁迫对西洋杜鹃叶片叶绿素荧光参数的影响

Effects of Low Temperature Stress on Chlorophyll Fluorescence Parameters of Rhododendron hybridum

低温伤害是限制西洋杜鹃产量和品质的主要因素之一,以其4个品种(系)‘五彩’、‘粉红’、‘梅红’、‘普红’的扦插苗为试验材料,分别在0、3、5、10℃中进行胁迫处理,研究不同低温下,西洋杜鹃叶绿素荧光动力学参数的变化。结果表明:低温胁迫下,西洋杜鹃幼苗叶片最大光能转换效率(F v/F m)显著下降、PSⅡ光下实际光化学效率(Yield)、光化学淬灭系数(qP)均同时下降;而非光化学猝灭系数(qN)则呈现上升趋势。从4个品种叶绿素荧光参数测定值看,‘普红’品种受害最严重,‘梅红’和‘五彩’次之,‘粉红’受冻害影响最小;西洋杜鹃幼苗对低温较敏感,低温伤害了光合机构,使其对光能的吸收、转换与光合电子传递均受到较显著的影响。

Chilling injury is one of major factors limiting the yield and quality of Rhododendron hybridum.The change in chlorophyll fluorescence kinetic parameters of four R.hybridum cultivars,i.e.,‘Wucai’,‘Fenhong’,‘Meihong’and ‘Puhong’was studied under low temperature stress gradient (0℃,3℃,5℃ and 10℃).The data obtained in this experiment showed that the maximum photochemical efficiency of PSⅡ (Fv /Fm ),the actual photo-chemical efficiency of PSⅡ(Yield),and the photochemical quenching coefficient (qP)all decreased simultane-ously under the low temperature stress,whereas the non-photochemical quenching coefficient (qN)showed a rising trend.It was indicated by the values of chlorophyll fluorescence parameters of the four R.hybridum cultivars that‘Puhong’was most affected,followed by ‘Meihong’and ‘Wucai’,and ‘Fenhong’was the least affected by freezing.These results indicated that R.hybridum was very sensitive to low temperature stress that could damage the photosynthesis apparatus,resulting in reduction in the light energy absorption,efficiency of light energy conver-sion and photosynthetic electron transport efficiency.