Effect of Endophytic Microorganisms on Growth Rate of Crops

Abstract

Increasing the yield of wheat, barley, and oats is a pressing issue. It largely depends on soil fertility. Mineral fertilizers, however, may be ineffective and unsustainable. As a result, microorganisms seem to be a promising alternative. The authors isolated endophytic microorganisms with growth-stimulating properties and assessed their effect on the growth rate of wheat, barley, and oats in laboratory conditions. The research involved spring soft wheat of the Sibirsky Alyans variety, spring oats of the Maruchak variety, spring barley of the Nikita variety, and standard bacterial strains (Azospirillum brasilense B-11094, Azotobacter chrococcum B-8739). The isolated bacteria were identified using a Vitex 2 Compact automatic microbiological analyzer. The production potential for indole-3-acetic and gibberellic acids was assessed spectrophotometrically. The nitrogen fixation potential was determined using a Rapid N Cube. The phosphate-solubilizing potential was tested on a calcium phosphate medium. The effect of the most promising strains on the growth rate was assessed in laboratory conditions. Seven isolates of endophytic microorganisms were identified as Pantoea allii Tri, Bacillus subtilis Tri 2, Bacillus subtilis Ave 1, Pantoea allii Ave 2, Bacillus subtilis Hor 1, Bacillus subtilis Hor 2, and Bacillus subtilis Hor 3. The most promising growth promoters ranged as follows. Bacillus subtilis Ave 1 fixed 790 μg/mL nitrogen, solubilized phosphates with index 1.60, and produced 7100 μg/mL indolyl-3-acetic acid and 343 μg/mL gibberellic acid. Bacillus subtilis Hor 1 fixed 760 μg/mL nitrogen, solubilized phosphates with index 1.44, and synthesized 4490 μg/mL indolyl-3-acetic acid and 409 μg/mL gibberellic acid. Bacillus subtilis Ave 1 demonstrated the greatest growth-stimulating activity. Bacillus subtilis Ave 1 could synthesize phytohormones, fix atmospheric nitrogen, and solubilize phosphates, which indicated good agricultural prospects. The strain increased the length of shoots and roots in wheat and barley, as well as boosted germination and shoot length in oats.