The impact of floating dust on net photosynthetic rate of Populus euphratica in early spring, at Zepu, northwestern China

Abstract

Floating dust weather is an annual natural phenomenon in early spring in south of Xinjiang UygurAutonomous Region, northwestern China. Floating dust in air can influence human health and plant growth. Populus euphratica is a rare tree species which can grow in hot and dry conditions. Some investigations have evaluated the effect of floating dust on plants by means of artificial dust to which simulates the natural sand and dust, but the mechanism by which plants respond to sand is poorly understood. The investigation presented in this paper focused on a comparison of the variation in net photosynthetic rate (P n ) before and during floating dust weather, to elucidate the mechanisms involved.Stomatal conductance (g s ) and P n appeared to increase during floating dust weather;in contrast, stomatal limitation (L s ) and non-stomatal limitation (L ns ) decreased with photosynthetic active radiation in the range 500 to 2000 μmol m −2 s −1 ,which is optimum for plant growth. Aerosol ions, including potassium, dissolved in water collected by foliar structures or tender stems, may come into contact with intercellular stroma and improve chloroplast activity or ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) levels, such as potassium, thereby influencing L s and L ns . Moreover, potassium, phosphorus, nitrogen and sodium in aerosols appeared to increase P n , and this may be due to nutrient compounds in aerosols, which may have a similar effect to spraying fertilizer on leaves. In addition, the high relative humidity and carbon dioxide concentration in air during floating dust weather may facilitate an increase in P n . AbstractFloating dust weather is an annual natural phenomenon in early spring in south of Xinjiang Uygur Autonomous Region, northwestern China. Floating dust in air can influence human health and plant growth. Populus euphratica is a rare tree species which can grow in hot and dry conditions. Some investigations have evaluated the effect of floating dust on plants by means of artificial dust to which simulates the natural sand and dust, but the mechanism by which plants respond to sand is poorly understood. The investigation presented in this paper focused on a comparison of the variation in net photosynthetic rate (Pn) before and during floating dust weather, to elucidate the mechanisms involved. Stomatal conductance (gs) and Pn appeared to increase during floating dust weather; in contrast, stomatal limitation (Ls) and non-stomatal limitation (Lns) decreased with photosynthetic active radiation in the range 500 to 2000 μmol m −2 s −1 ,which is optimum for plant growth. Aerosol ions, including potassium, dissolved in water collected by foliar structures or tender stems, may come into contact with intercellular stroma and improve chloroplast activity or ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) levels, such as potassium, thereby influencing Ls and Lns. Moreover, potassium, phosphorus, nitrogen and sodium in aerosols appeared to increase Pn, and this may be due to nutrient compo...