脱落酸对低温下雷公藤幼苗光合作用及叶绿素荧光的影响

Effects of exogenous abscisic acid(ABA) on the photosynthesis and chlorophyll fluorescence parameters of Tripterygium wilfordii seedlings exposed to low temperature.

以1年生雷公藤扦插苗为试材,研究低温胁迫下不同浓度外源脱落酸(ABA,0、5、10、15、20、25mg.L-1)叶面喷施处理对雷公藤叶片光合作用及叶绿素荧光参数的影响.结果表明:喷施20mg.L-1的ABA能显著提高雷公藤幼苗的抗冷性,减缓低温下雷公藤叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(gs)、胞间CO2浓度(Ci)的下降幅度,提高幼苗叶片的光合能力.低温处理6d后,随着ABA浓度上升,雷公藤叶片的初始荧光(Fo)下降,最大荧光(Fm)和PSII最大光化学效率(Fv/Fm)上升,PSII实际光化学量子产量(ΦPSⅡ)、光化学猝灭系数(qP)先下降后上升,而非光化学猝灭系数(qN)呈下降-上升-下降趋势.Pn、gs、qP、Fm和Fv/Fm均在20mg.L-1ABA处理时达到峰值.不同浓度ABA的相对电子传递速率(rETR)随着光化光强度增加呈先上升后下降的趋势,当光化光强度(PAR)达到395μmol.m-2s-1时,各处理的rETR达到最高值,其中25mg.L-1和20mg.L-1ABA处理分别比对照高17.1%和5.2%.雷公藤叶片ΦPSⅡ的光响应曲线均随光化光强度升高而下降,qN的光响应曲线则呈相反趋势.

Taking one year-old Tripterygium wilfordii cutting seedlings as test materials,this paper studied the effects of foliar spraying 0,5,10,15,20,and 25 mg·L-1 of abscisic acid（ABA） on the leaf photosynthesis and chlorophyll fluorescence characteristics of the seedlings under low temperature stress.Spraying 20 mg·L-1 of ABA increased the cold-resistance of the seedlings significantly,manifesting in the slowing down of the decrease amplitudes of leaf net photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（gs）,and intercellular CO2 concentration（Ci） and the increase of photosynthetic capacity.After 6 days exposure to low temperature,the initial fluorescence（Fo） decreased with increasing concentration of applied ABA,the maximum fluorescence（Fm） and maximal photochemical yield（Fv/Fm） increased,the actual photochemical efficiency of system Ⅱ（ΦPSⅡ） and photochemical quenching coefficient（qP） increased after an initial decrease,and the non-photochemical quenching coefficient（qN） showed a ＇decreasing-increasing-decreasing＇ trend.The Pn,gs,qP,Fm,and Fv/Fm reached their peak values at 20 mg·L-1 of ABA.In all treatments,with the increase of photosynthetically active radiation（PAR）,the relative electron transport rate（rETR） increased first and decreased then,reached the peak when the PAR was 395 μmol·m-2·s-1,and the peak value of the rETR in treatments 25 and 20 mg·L-1of ABA was 17.1% and 5.2% higher than that of the control,respectively.The light response curves of the ΦPSⅡ decreased with increasing PAR,whereas those of qN performed in adverse.