Plant-mycorrhiza symbiosis significantly affects plant community dynamic and composition in dry grasslands. On the other hand, fire is a natural component of many dry grasslands worldwide. Prescribed fire, as a restoration technique, may alter the plant-mycorrhiza relationships. However, its effects may vary on different plant species, and depending on the time of burning. Two prescribed fires were applied on spring (20th April) and autumn (30th October) 2015, in a dry grassland, Dehbar, Torghabeh, Northeast Iran. Soil sampling and mycorrhiza studies were conducted three times; i.e. 15th May 2015 (T1) and 15th May 2016 (T2) for spring burning (SB) also 15th of May 2016 (T3) for autumn burning (AB). Spring time burning (SB) initially (T1) increased (55%) mycorrhiza spore density in the burnt plots, but its effects were diminished after one year (T2). Mycorrhiza colonisation rate was also increased after SB, but it was higher in T1 (50%) than T2 (26%). Autumn burning increased both mycorrhiza spore density (33.3%) and inoculations (11.3%). In terms of plant species comparisons, the prescribed fires (SB & AB) increased mycorrhiza symbiosis (spore density and colonisation rate) with perennial shrubs (Astragalus gossypinus and Artemisia aucheri) and a rhizomatous grass (Agropyron trichophorum), but decreased symbiosis with ephemeral geophyte grass Poa bulbosa. Prescribed burning increased the mycorrhiza symbiosis with the bunchgrass Stipa arabica in the short term (T1) but reduced it after the relatively longer times in T2 and T3. In conclusions, prescribed burning may be beneficial for plant-mycorrhiza relationships in dry grasslands. Prescribed spring fire is more preferred, as it causes more positive effects on mycorrhiza symbiosis with perennial shrubs and grasses but negatively reduces symbiosis with the invasive and ephemeral species such as Poa bulbosa.

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