The effect of growth-promoting bacteria on the quantitative and qualitative agricultural traits of various cultivars of Solanum tuberosum under drought stress in the greenhouse and garden conditions

Potato (Solanum tuberosum L) is one of the tuberous products that plays an important role in the nutrition of the world's people, therefore, in order to investigate the effect of growth-promoting bacteria on the agronomic and qualitative traits of different potato cultivars, an experiment was carried out.  The conducted research in 2018 examined the effect of growth-promoting bacteria on the quantitative and qualitative agricultural traits of various cultivars of Solanum tuberosum under drought stress in greenhouse and garden conditions.  In the garden part, the hybrid of Enterobacter cloacae bacterium × 100% water requirements × Jelly cultivar with means of 48.53 ton/ha and 7.87 kg/m3 had the maximum tuber yield and water productivity, and the hybrid of no bacteria × 60% water requirements × Milva cultivar with means of 23.40 ton/ha and 3.8 kg/ha had the minimum tuber yield and water productivity among the treatments. Actually, using Enterobacter cloacae bacterium in addition to 100% water requirement increased tuber yield and water productivity up to 51.78 and 51.72%, respectively, compared to the no growth-promotion bacterium × 60% water requirements.  The indexes of tolerance (TOL) and sensitivity to water scarcity stress in the garden showed that Jelly cultivar in mild stress condition, Agria cultivar in severe stress condition in control treatment had minimum TOL than the other conditions according to TOL index. In addition, Jelly cultivar, when Enterobacter cloacae is used as a growth-promoting bacterium, was superior to the control treatment and use of Azospirillum bacteria according to YP, MP, and GMP indexes. It showed tolerance against the made stress and had a higher tolerance than the two other treatments in mild stress conditions.  In general, in laboratory, greenhouse and field conditions, water deficit stress caused the reduction of the evaluated traits. The use of Interbacterculase bacteria was effective in improving the proposed traits compared to its non-use bacteria and caused increasing in most of the proposed traits.