Evaluation the Effect of Mycorrhizal Inoculums on Plant Growth Regulator Levels and Quality of Minituber Production in Potato Plantlets

Microplants derived from tissue culture of two potato cultivars (Agria and Sante) were inoculated with two species of mycorrhizal fungi. Inoculation was being done when microplants transferred in to the greenhouse. A pot experiment was conducted using a factorial based on randomized complete blocks design with four replications. The factors were mycorrizal inoculation (non-inoculated and inoculated with Glomus mosseae، Glomus etunicatum and mixture of them) and two cultivars of potato. Eight weeks after inoculation، colonization percentage was assayed. In addition، plant growth regulators including Auxin، Cytokinin and Gibberellin were measured. After harvesting، minitubers were separated and total yield was estimated. In addition، dry matter of minituber was determined. Results showed that inoculants of mycorrhizae had significant effect (p≤0. 05) on colonization، minituber production and level of all plant growth regulators. Interaction effect of cultivar and inoculants in minituber size and weight was significant by probability of α= 0. 01 but was significant by probability of α= 0. 05 in Gibberellins levels and colonization percentage. By mean comparisons، it was demonstrated that inoculation with G. etanicatum and mixed inoculants had more positively effect on colonization severity، minituber production، and level of all plant growth regulators comparison with G. mosseae. The highest amount of minituber (13. 81 No and 40. 59 gr in mean weight per plantlet) was achieved in mixed inoculants that significantly (p≤0. 05) was different with two separated inoculants and control treatment. Dry matter of minituber was increased significantly (p≤0. 05) by application of mixed inoculant and separately mycorrhizal inoculants comparison with control treatment in two cultivars.