Investigating the role of periphyton types in the release and uptake of insoluble phosphorus in an in vitro experiment

Periphyton is a biological layer that is widely present in flood plains such as paddy fields and plays an important role in the nutrient cycle in such ecosystems. The role of this biological layer in dissolving and absorbing insoluble phosphorus in the country's paddy fields has not been recognized so far. This study was performed in the research laboratory of the department of soil science and engineering, university of Tehran in 2020 to investigate the role of periphyton grown in paddy fields of Guilan province in the release and absorption of phosphorus. For this purpose, 20 paddy fields in Guilan province were sampled from epipelon (LON) and epiphyton (TON). The results showed that about 68% of the population of autotrophic components in epipelon and epiphyton samples belonged to Chlorella and Chlorococcum. The genera Lyngbya, Scenedesmus, Nostoc and Navicula were the most abundant in the next ranks. The results of phosphate dissolution showed that samples of LON 6 and 13 and TON 8 have the highest solubility of phosphorus. Phosphorus uptake capacity was also very high in LON 6 and 13 samples and increased by 1840 and 2000% compared to the initial biomass, respectively. This amount was 825 percent in the TON 8. The results also showed that epipelon samples showed a higher ability than epiphyton samples in terms of phosphorus absorption and retention. In general, the results of this study showed that the periphytic biofilm has a high ability to absorb phosphorus, which reduces the waste of fertilizer used and therefore helps to increase its efficiency, and thus reduces non-point pollution.