Content of Photosynthetic Pigments in Sedum album L. and Sedum reflexum L. in Dry Weather Conditions of the Steppe Zone of Ukraine

The climate changes in the steppe zone of Ukraine are associated with the rise in temperature and prolonged droughts, and the consequences of their stressful action depend on the stage of plant development, as well as duration and severity of stress. Species of the genus Sedum L. have long been cultivated; however, these unpretentious multifunctional perennials are of limited use in artificial cenoses of the region. The purpose of this study was to determine the content of photosynthetic pigments during the growing season in S. album and S. reflexum in dry weather conditions of the steppe zone of Ukraine. It was found that the content of basic photosynthetic pigments (1.1‒3.5 mg/g of raw materials) was higher in the leaves of S. reflexum plants, with the predominance of Chl а in the total pigment amount at all phases of development. During flowering, the content of Chl b and of secondary peroxidation products in S. album increased significantly. In addition, the medium-strength direct correlation between the level of precipitation and the content of Chl а (r = +0.58) was found in S. album. In S. reflexum, the content of carotenoids increased during flowering, and correlation coefficients at the phase of completion of the vegetative growth indicated the strong inverse relationship (r = −0.95) of the content of all pigment forms with the air temperature. The study results revealed that the content of photosynthetic pigments and variation in their quantities in the leaves of S. album and S. reflexum were species specific, and these changes contributed to an increase in the protective mechanisms of the pigment system associated with the resistance to stress.