Evaluation of air pollution (dust) tolerance index of three desert species Seidlitzia rosmarinus, Haloxylon aphyllum, and Nitraria schoberi under salinity stress.

Dust causes adverse effects on the physiological and biochemical properties of plants, and under soil salinity conditions, these effects seem to be intensified, which limits their use in the development of the green belt around or within cities. In the research, the effect of salt (0, 30, and 60 dS m) on air pollution (dust, 0 and 1.5 g m 30 days) tolerance index (APTI), peroxidase activity, and protein content of three desert species Seidlitzia rosmarinus, Haloxylon aphyllum, and Nitraria schoberi was investigated. The results indicated that the use of dust alone did not change the concentration of total chlorophyll in H. aphyllum, while it decreased the concentration of total chlorophyll by 18% in N. schoberi and 21% in S. rosmarinus. Under salt stress conditions, before and after applying dust, the concentration of total chlorophyll decreased in S. rosmarinus and N. schoberi plants, but there was no change in H. aphyllum. The amount of ascorbic acid, peroxide activity, and pH increased significantly with increasing salinity level before and after applying dust. Applying dust alone increased pH value only in N. schoberi and the amount of ascorbic acid and peroxidase in all three plants. Applying dust alone reduced relative water content and APTI only in N. schoberi plant and the amount of protein in all three plants. At salinity level of 60 dS m and with application of dust treatment, APTI was decreased by 10, 15, and 9% compared to its control before application of dust, respectively, in H. aphyllum, N. schoberi, and S. rosmarinus plants. Therefore, it was found that N. schoberi, which may be used as a bioindicator of air quality, has a lower APTI than S. rosmarinus and H. aphyllum, which may be served as suitable sinks to survive the air pollution (the development of a design on green belt around or within the city), under conditions of simultaneous application of dust and salt.