Key message

In savin juniper, age and season can affect photosynthesis, chlorophyll fluorescence and photoprotective pigments. In spring, 2-year-old plants had more lutein than 5-year-olds, but the reverse occurred during summer and autumn.

Abstract

Savin juniper is an endemic evergreen shrub in the Mu Us Desert, where it establishes only with the protection of larger plants. Ultimately, established plants emerge into full sunlight as they grow. To explore how photoprotection responses change during this transition, a pot study was established under field conditions with three sunlight regimes (10%, 50% and 100% light transmittance) and two age cohorts (1- and 4-year-old rooted scions). To avoid potentially confounding effects of differences in leaf form, after one year we measured photosynthesis, chlorophyll fluorescence and foliar pigments of 2- and 5-year-old savin juniper on a monthly basis from April to October. For gas exchange and fluorescence variables, there were no interactions between cohort and sunlight except for intrinsic water-use efficiency in June; however, there were many interactions regarding pigment concentrations and ratios. Generally, 5-year-old plants had higher mean chlorophyll, total carotenoids, and chlorophyll a/b ratios than 2-year-old plants, but lower mean β-carotene/α-carotene ratio, zeaxanthin and lutein. Plants under brighter light had lower mean lutein. There were obvious changes in β-carotene/α-carotene, zeaxanthin and lutein in June, July and August, respectively. Under 100% sunlight, lutein concentration was higher in 2-year-old than 5-year-old plants from April to June, but this pattern reversed from July to October. The effects of age and season, in addition to the prevailing light regime, need to be considered when investigating the role of carotenoids in photoprotection.

中文翻译：

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遮荫和阳光下不同陈年杜松植物的光保护反应的季节性进程

关键信息

在杜松子酒中，年龄和季节会影响光合作用，叶绿素荧光和光防护色素。在春季，2年生植物的叶黄素含量高于5年生植物，但相反的情况发生在夏季和秋季。

抽象的

Savin杜松是Mu Us沙漠中的一种地方性常绿灌木，只有在保护较大植物的情况下才能建立。最终，成熟的植物会随着生长而充满阳光。为了探索在此过渡过程中光保护反应的变化，在三个阳光条件下（透光率分别为10％，50％和100％）和两个年龄组（一岁和四岁的接穗子）在田间条件下进行了盆栽研究。 。为了避免叶形差异的潜在混淆影响，一年后，我们从4月到10月每月测量2岁和5岁沙文杜松的光合作用，叶绿素荧光和叶色素。对于气体交换和荧光变量，除了六月份的内在用水效率外，队列与阳光之间没有相互作用。然而，关于颜料浓度和比例有许多相互作用。通常，5岁植物的平均叶绿素，总类胡萝卜素和叶绿素均较高。a / b的比例比2岁的植物高，但平均β-胡萝卜素/α-胡萝卜素，玉米黄质和叶黄素的平均含量较低。光照条件下的植物平均叶黄素含量较低。β-胡萝卜素/α-胡萝卜素，玉米黄质和叶黄素分别在6月，7月和8月发生明显变化。在100％的阳光下，从4月到6月，2岁植物的叶黄素浓度高于5岁植物，但是从7月到10月，这种模式发生了逆转。在调查类胡萝卜素在光保护中的作用时，除了普遍使用的光照方案外，还应考虑年龄和季节的影响。