水杨酸对温度胁迫下紫御谷幼苗生长及光合特性的影响

以紫御谷为材料,研究了水杨酸对温度胁迫(高温和低温)下紫御谷幼苗生长及光合特性的影响,结果表明:①高温和低温胁迫显著降低了紫御谷幼苗的根冠比、根系活力、总根长和平均根直径,使根系生长受到抑制,而水杨酸处理则提高了其根冠比、根鲜物质量、茎鲜物质量和根系活力;②高温胁迫显著降低了紫御谷叶片的叶绿素a、总叶绿素质量分数和净光合速率,而水杨酸处理显著提高了紫御谷叶片的净光合速率.低温胁迫使紫御谷幼苗叶片的净光合速率、气孔导度和蒸腾速率均显著低于常温对照,而水杨酸处理后,叶片的净光合速率、气孔导度和蒸腾速率均有所升高.③高温胁迫下,紫御谷幼苗的初始荧光(Fo)、光化学量子效率(Fv/Fm)和光下PSⅡ实际光化学效率(ΦPSⅡ)与常温对照相比差异不显著,而低温胁迫下的Fv/F和ΦPSⅡ则显著低于常温对照,喷施水杨酸后Fv/Fm和ΦPSⅡ均低于低温处理组,且Fv/Fm差异显著,由此推断低温胁迫可能使PSⅡ反应中心受到不可逆的损害.

Effects of Salicylic Acid on the Growth and Photosynthesis Characters of Purple Majesty (Pennisetum glaucum) During Temperature Stress

The effects of salicylic acid on the growth and photosynthesis of Purple Majesty(Pennisetum glaucum) grown under high temperature stress and low temperature stress were studied.Both high and low temperature stress resulted in significant reduction in root/shoot ratio,root activity,total length of the root and average diameter of the root,while salicylic acid increased root/shoot ratio,root fresh weight,stem-leaf fresh weight and the activity of root.High temperature stress reduced the contents of chlorophyll a and total chlorophyll and net photosynthesis rate,while the salicylic acid treatment significantly increased net photosynthesis rate.Compared with the normal temperature control group,low-temperature stress significantly decreased net photosynthesis rate,stomatal conductance and transpiration rate,and the salicylic acid treatment increased these indicators slightly.Compared with the normal temperature control group,high temperature stress generated little effect on Fo,Fv/Fm and ΦPSⅡ of the seedlings.Low temperature stress significantly reduced the Fv/Fm and ΦPSⅡ.Spray of salicylic acid on the plants under the low-temperature,we found the Fv/Fm and ΦPSⅡ still reduced and inferred that the ΦPSⅡ may be irreversibly damaged under the low-temperature stress.