Diversity of structural and functional parameters of the photosynthetic apparatus among hydrophilic plants of the Maksimikha River (Republic of Buryatia, Russia)

Abstract

Structural and functional parameters of leaves were studied in 21 dominant and abundant species growing in shallow waters and excessively moistened banks at the mouth of the Maksimikha River (Barguzinsky district, Republic of Buryatia). The analysis of the variation coefficients revealed that in hydrophilic plants, the most variable were indicators associated with the size of the leaf blade - the area and thickness of the leaf (170 and 130 %, respectively). The parameters associated with the leaf structure, leaf density and dry matter content (DMC), depended on the degree of plant hydrophilicity. On average, the leaves of hygrophytes had denser leaves (by 41 %) with a higher DMC (by 38 %) compared to helophytes. The functional photosynthetic apparatus indicators of wetland plants, such as the content of chlorophylls per unit mass and leaf area, as well as the rate of CO2 uptake, were the most stable among the studied parameters (variation coefficients were 37, 33, and 29 %, respectively). On average, hygrophyte leaves had a 38 % lower transpiration rate and 29 % higher water use efficiency compared to helophytes. It was concluded that with a decrease in the degree of hydrophilicity of plants in the series helophytes - hygrophytes, the structural rearrangement of the leaf occurs in the direction of increasing its density and dry matter content, which is accompanied by a decrease in the transpiration rate and an increase in the water use efficiency.