Phytoremediation of nitrogen-contaminated soil by Atriplex lentiformis, Atriplex canescens and Atriplex leucoclada

In this study, the ability of three rangeland species Atriplex halimus, A. canescens and A. lentiformis to remove nitrate from soil in vitro (greenhouse) in a completely randomized design was investigated. For this purpose, potassium nitrate salt (KNO3) was used in four treatments control, 6.3 ppm, 9.5 ppm and 14.5 ppm in three repetitions. Plant species used in this study with an approximate age of 6 months were prepared from the village of Chaparquimeh, Gonbad Kavous city in Golestan province. Selected species were cultivated in nitrate-contaminated soils with the concentrations mentioned and after a period of three and six months, the amount of dry weight and nitrogen of aerial and underground organs of the species and the amount of nitrate in the soil were measured. With increasing salt concentration from 6.3 ppm to 14.5 ppm, the amount of dry weight of aerial parts in A. canescens  has decreased from 28.31 ppm to 14.05 ppm, in A. halimus from 28.83 ppm to 11.75 ppm and in A. lentiformis from 39.17 ppm to 16.05 ppm . A downward trend was observed in the amount of dry weight of underground organs in the studied species, so that by increasing the salt concentration from 6.3 ppm to 14.5 ppm, the amount of underground dry weight in A. canescens  from 8.31 ppm to 5.05 ppm, in A. halimus from 6.83 ppm to 4.75 ppm and in A. lentiformis decreased from 10.17 ppm to 6.47 ppm. The results of study showed that the level of soil nitrate removal at different concentrations decreased in all three species. The percentage of soil nitrate removal efficiency by A. canescens at concentrations of 6.3 ppm, 9.5 ppm and 14.5 ppm is 71%, 52% and 37%, respectively, by A. halimus are reported to be 62%, 45% and 38%, respectively. However, A. lentiformis removed nitrate at a higher level than the other two species with 80%, 64% and 47%, respectively. The results showed that with increasing the concentration of this contamination in the soil, the phytoremediation capacity of the studied species decreased and A. lentiformis with high nitrogen storage in its tissues has an effective role in clearing nitrate-contaminated soils.