Primary screening of growth-stimulating properties of rhizosphere microorganisms in relation to tomato seeds

The ability of bacterial isolates isolated from the rhizosphere of cultivated and wild plants of arid ecosystems of the Astrakhan region, which have the ability to tryptophan-induced synthesis of indolyl-3-acetic acid, to stimulate the germination of tomato seeds of the varieties “Sanka”, “Volgogradsky”, “Cosmonaut Volkov”, was studied. “Newbie” Experimental studies were carried out through laboratory experiments by incubating seeds in humid chambers; laboratory germination and morphometric parameters of seedlings were assessed. It was revealed that most of the studied suspensions of isolates have a stimulating effect on tomato seeds. High germination (90% or more) of seeds of the “Sanka” variety was observed when 12 isolates were treated with suspensions; variety “Volgogradsky” – suspensions of 9 isolates; variety “Cosmonaut Volkov” – suspensions of 2 isolates; variety “Novichok” – suspensions of 3 isolates. Suspensions of isolates 16/19 and 31/20 contributed to high germination of seeds of all varieties: up to 86.6–100% and 90–100%, respectively, and isolate 9/19 significantly reduced the germination of seeds of the varieties “Volgogradsky”, “Cosmonaut Volkov” and “Novichok” by 66.6–56.7%. When assessing the morphometric parameters of seedlings in the experiment, it was noted that the suspension of isolate 16/19 helps to increase the biomass of the varieties “Sanka”, “Volgogradsky” and “Cosmonaut Volkov” up to 273–449%. Suspension of isolate 31/20 has a stimulating effect on the morphometric parameters of seedlings of all varieties: it stimulates root development by 73.3–183.3%, stem development by 46.8–100.5%. The isolate 9/19 suspension not only inhibits seed germination, but also causes a reduced accumulation of seedling biomass, inhibits the development of roots and stems of seedlings of the varieties “Volgogradsky”, “Cosmonaut Volkov” and “Novichok”. Thus, during experimental studies, isolates (16/19 and 31/20) of rhizosphere bacteria were identified that have a stimulating effect on both the germination of tomato seeds and the morphometric parameters of seedlings.