Efficiency of plant growth-promoting rhizobacteria and fungi on enhancement of growth and minituber production of tissue-cultured potato cultivars (Solanum tuberosum)

The effect of plant growth promoting rhizobacteria (PGPR) and arbucular mychorizal fungi (AMF) on the growth and minituber yield of micropropagated potato cultivars (Agria, Arinda and Marfona) were investigated under organic conditions. The experiment design was completely randomized design with 5 replicates. Three PGPR strains (Pseudomonas CHAO-4, Azotobacter DSM-281 and Bacillus PTCC-1020) and AFM (Glomus intraradice) as a commercial fertilizer were tested alone or in combination on organically grown potato cultivars in term of growth and minituber yield. The results showed that all of the biological treatments stimulated plant growth and resulted in significant yield increase. Among different groups of inoculation, treatment of plants with triad inoculation in general and combination of Azotobacter + Pseudomonas + Glomus in particular produced the highest plant height and shoot dry weight in all cultivars. In addition, the highest minituber yield in all cultivars was observed in plants treated with Azotobacter + Bacillus + Glomus. Furthermore, the results of path analysis indicated that minituber size and number of minitubers had positive and high direct effects on minituber yield of potato cultivars. The results of this study suggest that PGPR and AMF have the potential to increase growth and minituber yield of potato cultivars under organic growing conditions.