Dear Ebrahim;

I guess high air and soil temperature during summer, as well as  low soil water content caused by high evapotranspiration, may prevent cell division and growth of mycorhiza.

Regards

Please contact Prof Ghazi,

https://www.researchgate.net/profile/Ghazi_Al-Karaki

Dear Ebrahim

It has been demonstrated that seasonal water fluctuations affect mycorrhizae dynamics (Guadarrama, & Álvarez Sánchez, 1999; Lugo & Cabello, 2002). Many studies have been performed on the seasonal fungal community abundance patterns and, more specifically, on the variation of AMF formation of spores (Cuenca, & Lovera, 2010).

However the results about the colonization levels with the season are not consistent in the literature. In western Cuba for example we have found in general, greater mycorrhizal colonization in the wet periods. Apple et al. (2005) and Cuenca and Lovera (2010) also reported higher mycorrhizal colonization of plant roots in the rainy period in other tropical and desert environments. Lugo and Cabello (2002) found the highest spore density in the dry seasons (autumn and WINTER) coincident with the lack of flowering and fruting, and the end of the growth season, therefore physiological mechanisms related with the plant development are also involved in that response.

• Cuenca, G., & Lovera, M. (2010). Seasonal variation and distribution at different soil depths of arbuscular mycorrhizal fungi spores in a tropical Sclerophyllous shrubland. Botany, 88, 54-64.

• Guadarrama, P., & Álvarez-Sánchez, F. J. (1999). Abundance of arbuscular mycorrhizal fungi spores in different environments in a tropical rain forest, Veracruz, Mexico. Mycorrhiza, 8(5), 267-270.

• Lugo, M. A., & Cabello, M. N. (2002). Native arbuscular mycorrhizal fungi (AMF) from mountain grassland (Córdoba, Argentina) I. Seasonal variation of fungal spore diversity. Mycologia, 94(4), 579-586.

Dear Edurado

thank you very much for valuable answer and suggestion.

 best regrades

 Ebrahim