Effect of arbuscular mycorrhizas Glomus intraradices and Glomus mosseae on ‎pistachio root rot caused by Phytophthora under salinity stress

The effect of Glomus intraradices and G. mosseae (Gm+Gi) as Arbuscular mycorrhizal fungi (AMF) was investigated on Phytophthora root rot of pistachio seedlings caused by Phytophthora drechsleri (Pd) in salinity level of 1400 and 3200 mg NaCl per gram of soil. Two month old pistachio seedlings cultivar Badami-Zarand were inoculated by 200 propagules gr-1 of Gm+Gi mycorrhizae and after 50 days, salinity treatments with different concentration of NaCl were added to seedling pots through irrigation during 15 days. After two weeks, seedling roots were inoculated by P. drechsleri. The results showed that seedlings inoculation by mycorrhizae, significantly increased the shoot and root dry weight, leaf area, seedling height, chlorophyll and soluble sugars concentration in all salinity levels as well as non-saline treatments. But proline concentration as well as Na and Cl ions were reduced in shoot and root of mycorrhizal seedlings. P. drechsleri inoculation could have no significant effects on root colonization by AMF whereas in myorrhizal seedlings, the colonization of pathogen was significantly decreased in all salinity treatments. The results of the interaction treatment of AM fungi and P. drechsleri showed that the shoot and root dry weight, leaf area, seedling height, chlorophyll and soluble sugars concentration were significantly increased in all salinity levels compared to P. drechsleri inoculated seedlings whereas the concentration of Na and Cl ions in shoot and root was significantly lower. In conclusion, the presence of AM fungicould reduce the destructive effects of salinity and Phytophthora root rot of pistachio.