低温弱光下辣椒幼苗叶绿素荧光特性及其与品种耐性的关系

Chlorophyll Fluorescence Characteristics of Pepper Seedlings Under Low Temperature and Weak Light and Their Relationship to Varieties Tolerance

选取4份耐低温弱光性不同的辣椒品种,以耐低温弱光指数作为品种耐性鉴定的依据,研究了四叶一心期,昼/夜温度10℃/5℃,光照70μmol·m-2·s-1的低温弱光下叶片叶绿素荧光特性,分析了其与耐低温弱光指数的关系。结果表明,低温弱光处理后,辣椒叶片的初始荧光(Fo)、最大荧光(Fm)、光合系统Ⅱ(PSⅡ)最大光化学量子产量(Fv/Fm)和光化学淬灭系数(qP)呈降低趋势;非光化学淬灭系数(q N)在处理3和5 d显著上升,处理7 d,非耐性品种qN显著下降,耐性品种qN显著上升或无显著变化;最大相对电子传递速率(rETRmax)和快速光响应曲线初始斜率(α)呈下降趋势;半饱和光强(Ik)在非耐性品种中呈下降趋势,但在耐性品种中呈上升趋势;随着光照强度不断增强,qP不断下降,但耐性品种发生完全光抑制的光强显著大于非耐性品种。Fo、Fm、qP、qN、Fv/Fm、rETRmax、α、Ik等叶绿素荧光参数与耐低温弱光指数显著相关,其中r ETRmax最稳定灵敏。qP光响应曲线和r ETRmax可作为实际生产中辣椒耐低温弱光的主要筛选指标。

Effects of low temperature（10 ℃/ 5 ℃）and weak light（70 μmol · m-2 · s-1）on chlorophyll fluorescence characteristics of four pepper varieties at seedling stage were studied,and moreover,correlations between the chlorophyll fluorescence characteristics and chilling and weak-light resistance indexes were analyzed. The results indicated that minimal fluorescence（Fo）,maximum fluorescence（Fm）,maximum quantum yield of photosystem Ⅱ photochemistry（Fv/Fm）and photochemical quenching（qP）decreased after treatment. Non photochemical quenching（qN）significantly increased after 3 and 5 days treatment. After 7 days treatment,the qN significantly decreased in the sensitive varieties but significantly increased or didn＇t changed significantly in the resistant varieties. Maximum electron transport rate（r ETRmax）and initial slope（α）decreased in all varieties. The minimum saturating irradiance（Ik）declined in the sensitive varieties but increased in the resistant varieties. The qP continuously decreased along with increased light intensity,however,the light intensities of complete light inhibition of the resistant varieties were significantly higher than that of sensitive varieties. Significant correlations between Fo,Fm,Fv/Fm,qN,qP,r ETRmax,α,Ik and the chilling and weak-light resistance indexes were observed,and among these parameters,r ETRmax was the most stable and sensitive one. In practice,r ETRmax and the light responsive curve of qP could be used as primary tools for identification and screening chilling and weak-light tolerant pepper varieties.