高温干旱胁迫对白及光合特性及叶绿素荧光参数的影响

摘要

In order to study the effects of heat and drought stress on the photosynthesisof Bletillastriata,two-year-old Bletilla was used as a basic material.The plants were grew in a growth chamber.Four treatments of heat,drought,combination of high temperature and drought,and control.The changes of photosynthesis and chlorophyll fluorescence characteristics in the leaves were measured after 0 d,7 d,14 d and 21 d treatments.The results showed that high temperature and drought stress inhibited the growth and photosynthesis of Bletilla.Under the three kinds of stress,the photosynthetic parameters of Bletilla,the net photosynthetic rate,stomatal conductance and transpiration rate of the treatments were significantly decreased.Photochemical efficiency (Fv/Fm),maximum quantum yield (Yield),and apparent photosynthetic electron transport rate (ETR) of photosystemⅡ (PSⅡ) were decreased gradually as longer time of treatment,but the initial fluorescence (Fo) and NPQ were increased.The decrease of photosynthetic parameters was much higher than those of chlorophyll fluorescence parameters under stress,which indicated that high temperature (36℃) and longer drought period (21 d) affected the photosynthesis of the leaves of Btetilla,it did not damage the light reaction system did not bring irreversibly.%为研究高温和干旱胁迫对白及光合作用的影响,以2a生白及为试材,利用人工气候培养箱设置高温、干旱、高温干旱和对照4个处理,于处理的0、7、14和21d分别测定各处理白及叶片光合和叶绿素荧光特性的变化情况.结果表明:高温、干旱和高温干旱复合胁迫均抑制白及的生长和光合作用.在3种胁迫下,白及叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)等光合参数降低明显;光系统Ⅱ(PSⅡ)光化学效率(Fv/Fm)、最大量子产额(Yield)、表观光合电子传递速率(ETR)等叶绿素荧光参数在试验处理的过程中随着试验的进行逐渐降低,初始荧光(Fo)和NPQ则有所增加.虽然光合参数和叶绿素荧光参数在胁迫下都呈现下降趋势,但光合参数的降低远大于叶绿素荧光参数的降低程度,这表明高温、干旱和高温干旱复合胁迫只影响了白及叶片的光合参数,而对光反应系统并没有造成不可逆的破坏.