Effect of the simulated dust storm stress on the chlorophyll a fluorescence, Chlorophyll content, Flavonoids and phenol compounds in medicinal plant Thymus vulgaris L.

One of the major problems in recent years is the more dust storms occurrence in west regions of Iran in order to rising of the temperature and drought in the neighbored country (Iraq). In present investigation، effect of simulated dust storm on chlorophyll a fluorescence، chlorophyll content and phenol compounds surveyed in vitro in medicinal plan Thymus vulgaris. T. vulgaris is the aromatic medicinal plant with high economic value. This plant was stressed for a period of 2 months in the dust chamber as 0. 5، 1 and 1. 5 grams/m3 amount with four day intervals. After this period، results showed reverse relationship between dust amount and plant chlorophyll content and chlorophyll a fluorescence. Chlorophyll a and b content decreased with increase of the stress. Photosynthesis yield (ΔF/Fm´) had not significant reduction in first treatment (2%) and second treatment (21%)، while it illustrated significant reduction in third treatment (28%). Electron transport rate (ETR) had significant decrease in T2 and T3 by 24% and 39% respectively. Also، there was increasing in treatments than to control in flavonoids and Anthocyanin. In the base of results in this investigation، high amount of the dust can has reduced effect on the photosynthesis performance.