Rhizobacterial Isolates from the Native Plant Ceanothus velutinus Promote Growth in Two Genotypes of Tall Fescue

Global warming-induced climate change haunts the world, posing a critical threat to plant health and crop production. Overusing chemical fertilizers and pesticides poses a significant threat to soil health. Ceanothus velutinus (snowbrush) is a drought-tolerant, actinorhizal native plant found in the Intermountain West region of the US that harbors many plant growth-promoting rhizobacteria (PGPR). In this study, we evaluated the effects of PGPR CK-06, CK-22, CK-44, and CK-50 from C. velutinus on the growth and development of two tall fescue genotypes: (i) a lawn-type tall fescue blend and (ii) an endophyte-free forage-type tall fescue known as Armory. Tall fescue plants were grown in field soil and sand mix in pots and treated twice with 5 mL of bacterial inoculum. Two isolates, CK-06 and CK-22, significantly increased tiller numbers (p < 0.05) in the lawn-type tall fescue blend, and all isolates showed a significant increase in fresh and dry weight compared to the control. Isolate CK-22 significantly increased the tiller number and fresh and dry weight of the forage-type tall fescue Armory compared to the control. Isolates CK-44 and CK-50 tested positive for sulfur-oxidizing properties, and CK-44 was able to restore the sulfur content in sulfur-deficient soil compared to the control.