Effect of salinity and different Mg/Ca ratios on mycorrhiza colonization and vegetative traits of Sorghum bicolor

Mycorrhizal fungi are capable of symbiosis with plants. They improve plant growth by increasing absorption of nutrient elements and decreasing salinity and toxicity of some elements. In the present research، the effect of different salinity levels and Mg/Ca ratios on mycorrhiza colonization of Glomus sp. and vegetative traits of Sorghum bicolor was studied in a factorial greenhouse experiment، based on a completely randomized design with 3 replications. The factors were two mycorrhiza levels (control and inoculated with mycorrhiza)، three salinity levels (2، 5 and 10 dS/m) and four Mg/Ca ratios (0. 5، 1، 2 and 4). Results showed that shoot and root weight (dry and wet) and shoot length decreased with increased salinity، but the decrease in the traits of inoculated treatments with mycorrhiza was significantly lower than non-treated samples (P<0. 05). Colonization percentage in salinity level of 10 dS/m decreased from 62. 17% (control) to 30. 67%. Both dry and wet weight of root and shoot and colonization percentage increased as Mg/Ca ratio increased، and inoculated plants showed more increase in wet and dry weight. Comparison of interaction effects of Mg/Ca ratio and mycorrhiza clearly showed that colonization percentage was significantly increased. It seems that inoculation has an important role in increasing growth parameters and decreasing negative effects of salinity and magnesium in sorghum plant.