Photosynthetic Pigments in Silver Birch Leaves (Betula pendula Roth.) with Technogenic Load

Abstract

The content of photosynthetic pigments in silver birch leaves (Betula pendula Roth.) is studied in areas with technogenic load and in baseline conditions. The research is performed in a forb type of birch forest in the suburbs of Krasnoyarsk. The wood stands exposed to a high level of technogenic pressure are located to the east of the city in the prevailing direction of air mass movement. The reference stands are under the least technogenic pollution and grow in western and northern areas of the city. The photosynthetic pigments are determined in ethanol extracts, calculated per 1 g of absolute dry mass (a.d.m.) of the leaves. A level of dust deposition on leaf surfaces is evaluated according to the method of J. Detrie (1973). The amounts of zinc, lead, aluminum, and fluorine ions are estimated in the washed leaves. It is found that the content of chlorophyll a inside the birch leaves from a relatively clean environment is slightly lower compared to the concentration in the leaves with the technogenic load. The chlorophyll b concentration is 2.5–3 times less than chlorophyll a and is close to the amount of carotenoids. The total chlorophyll content in birch leaves from different locations ranges from 5.4 to 7.3 mg/g a.d.m., the ratio of chlorophyll forms varies from 2.5 to 3, the proportion of net chlorophyll to carotenoids is between 3.4 and 3.8. As the level of dust increases, the content of the total photosynthetic pigments also rises. The accumulation of zinc ions in the birch leaf cells has a negative effect on pigment content, especially chlorophyll a, but doesn’t correlate with the ratio of the pigments. There has not been any correlation found between the lead and the photosynthetic pigments. It is noted that the rise in the concentration of aluminum significantly affects the contents of the chlorophylls and the carotenoids, while no relationship has been discovered between the concentration of aluminum and the proportion of the pigments. The relationship between fluorine and different forms of chlorophyll is absent as well. The results indicate the adaptive response of the photosynthetic system to the presence of pollutants in concentrations below the threshold values that are indicated in the literature. For citation: Stasova V.V., Skripal’shchikova L.N., Astrakhantseva N.V., Barchenkov A.P. Photosynthetic Pigments in Silver Birch Leaves (Betula pendula Roth.) with Technogenic Load. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 35–47. (In Russ.). https:// doi.org/10.37482/0536-1036-2023-3-35-47