Comparison of air pollution tolerance index in two species of Haloxylon aphyllum and Nitraria schoberi under dust conditions

Identifying suitable plant species to create green belts around cities in arid and desert areas, in order to reduce air pollution is very important. Air pollution tolerance index is one of the known indicators to determine the tolerance of plant species to air pollution. The aim of this study was to investigate the effect of dust on the physiological and biochemical characteristics of two halophyte species of Haloxylon aphyllum and Nitraria schoberi and to determine the appropriate species for green belt. The experiment was done in a factorial experiment in a completely randomized design, with two treatments (no dust and dust) in three replications for 5 months in greenhouse conditions. In order to investigate the effect of dust, dusting was performed on the samples with a time interval of one week (1.5 g/m2/month) using a dust simulator. Finally, the parameters of ascorbic acid, total chlorophyll, relative water content and pH of leaf extract and finally the air pollution tolerance index of the two species were measured. The results showed that the total chlorophyll parameter of H. aphyllum and N. schoberi decreased by 8 and 19%, respectively, compared to the control, while relative water content increased by 3 and 8%, respectively. The pH of N. schoberi leaf extract increased by 29% compared to the control. The highest APTI value of 8.15 was related to H. aphyllum and the lowest APTI value of 7.41 was related to N. schoberi species. According to the obtained results, despite the small differences between the air pollution tolerance index of the two species, H. aphyllum species can be a suitable option for planting a green belt to reduce air pollution due to its higher tolerance index and plant height than N. schoberi.