油蒿(Artemisia ordosica)光化学量子效率和非光化学淬灭的动态及其影响因子

Temporal variation and controlling factors of photochemical efficiency and non-photo-chemical quenching in Artemisia ordosica

叶绿素荧光的测定是探究干旱半干旱区沙生植物对环境变化响应的重要手段,叶绿素荧光的动力学研究对认识植物适应环境胁迫的生理生态过程与机制具有重要意义。本文于2012年6-10月研究了宁夏盐池油蒿（Artemisia ordosica）的光化学量子效率（Φ）和非光化学淬灭（NPQ）的季节变化和日变化,及其与光合有效辐射（PAR）、相对湿度（RH）和空气温度（Ta）的关系。结果表明：在观测期内,油蒿的Φ随PAR和Ta升高而降低,随RH的升高而升高,NPQ的变化与Φ相反;在日变化尺度,油蒿的Φ（R2〉0.92）和NPQ（R2〉0.90）与PAR紧密相关,而与空气温度（Ta）和相对湿度（RH）的日变化存在3-4 h的滞后;此外,在相同PAR下,生长季前期的Φ大于后期,生长季旺期的NPQ大于末期;因此,PAR、Ta和RH对Φ和NPQ均有影响。

Knowledge on the dynamics and environmental controls of leaf chlorophyll fluorescenceis important in understanding how plant physiological processes respond to abiotie stresses such asdrought, strong radiation and extreme temperature in arid and semiarid ecosystems. Therefore,chlorophyll fluorescence measurements are an effective tool for exploring plant adaptive strategies.We conducted in situ field measurements of chlorophyll fluorescence on Artemisia ordosica inYanchi, Northwest China from June to October in 2012. The objectives were to explore seasonaland diurnal variations of chlorophyll fluorescence parameters, and to examine the relationshipsbetween chlorophyll fluorescence parameters and environmental factors. The results showed thatthe photochemical efficiency （Φ） decreased with increasing photosynthetically active radiation（PAR） and air temperature （Ta）, but increased with relative humidity （RH）. Therefore, PARwas likely the primary factor driving the changes in chlorophyll fluorescence parameters. Both qband the non-photochemical quenching （NPQ） of A. ordosica varied with PAR on a diurnal basis.The diurnal trends of both Ta and RH, however, lagged the chlorophyll fluorescence parametersby 3-4 h. Given the same PAR, Φ5 in the early growing season was greater than that in the lategrowing season, and NPQ was higher in the mid-growing season period than at the late stage ofthe growing season.