Effects of atmospheric dust deposition on leaf chlorophyll fluorescence parameters of cow-tail shrubs (Smirnovia iranica) in the desert regions of Kashan, Iran

Abstract

Smirnovia iranica, a native valuable woody species from Fabaceae, is an adaptable plant
from the central sandy areas of Iran. Changes in chlorophyll fluorescence and
photosynthetic pigment characteristics were analysed in the course of dust accumulation
during April (Ap); April and May (AM); and April, May and June (AMJ) periods,
respectively. The results obtained from the analysis of variance indicated that there was a
significant difference among different dust-loading periods of S. iranica in terms of the
characteristics mentioned. Extending dust accumulation resulted in a significant reduction
in the Fv /Fm ratio in AM and AMJ. A significant effect of dust deposition on thermal
dissipation of the light energy (D) value was observed in AM and reached the highest value
in AMJ. In all evaluated plants, during the course of dust accumulation, there was a
decrease in the photochemical efficiency of photosystem II (ΦPSII), and from AM. A
similar influence of the extending dust accumulation periods on ΦPSII was observed for the
electron transport rate (ETR). Our results proved that dust deposition decreased overall
plant performance through its severe effect on pigment content and resulted in a significant
inhibition of PSII efficiency throughout this study period.