DETERMINATION OF THE ENDOMYCORRHIZOGENIC POTENTIAL OF PHOSPHATE LAUNDERED SLUDGE BY USING THE MYCORRHIZAL INFECTIOUS METHOD (PIM)

Mycorrhizae are symbiotic associations between soil fungi and the roots of most plants. They promote their growth and resistance to many biotic and abiotic stresses. The use of arbuscular mycorrhizal fungi in agriculture limits the use of several chemical inputs. To manage the diversity of endomycorrhizae, it is necessary to know their abundance in the soil and to evaluate their mycorrhizogenic infectious potential (MIP). In this study, this mycorrhizogenic infectious potential of soil amended with phosphate sludge soil was evaluated by a bioassay test that measures the ability of endomycorrhizae in phosphate sludge to colonize the roots of a trap plant, for example sorghum. The results obtained showed that the mycorrhizogenic infectious potential of the phosphate sludge from basins B, C, D, and the rhizospheric soils of olive and Tamarix have the highest infectious potential and the lowest IPM50, respectively in the order of 3.33; 2.18; 0.04; 1.34; and 2.3 units/100 g soil. On the other hand, sludge from basins A and F showed the lowest infectious potential and the highest PIM50 (79; 24.89; /100 g soil). At a concentration of 100% sludge, the number of spores in soil samples from basin A and F were 35 and 13 spores/100 g of soil respectively. The average frequency of mycorrhization of sorghum roots and mcorrhization intensity (42%) were highest (100%) in the sludge from basin D compared to sludge A with a rate of 69% and 23% respectively. Similarly, the highest arbuscular content was found in sludge C (37%), and the lowest in sludge A (15%).

It seems, therefore, that the phosphate sludge from the various basins studied contains endomycorrhizae, able to form mycorrhizal associations with different mycotrophic plant species.