INFLUENCE OF STRESS-TOLERANT BACTERIA ON THE MORPHOMETRIC AND BIOCHEMICAL PARAMETERS OF SPRING WHEAT GROWN IN SOIL WITH COPPER(II) CHLORIDE

Abstract

This study examines the influence of inoculating spring wheat (Triticum aestivum L., cv. Tybalt) seeds with stress-tolerant bacterial strains isolated from Antarctic substrates, Lviv municipal solid waste landfill leachates, and war-affected soils on seedling growth under exposure to copper(II) chloride (300 mg/kg). Copper toxicity was shown to cause a 4.5-fold reduction in root length, a 15% decrease in the chl a/chl b ratio, and an accumulation of flavonoids and proline in the leaves of non-bacterized seedlings. Inoculation of wheat seeds with the strains Ochrobactrum sp. K3, Microbacterium sp. EO1, Rhodococcus sp. 37, Bacillus sp. S304, Pseudomonas sp. EO2, and Paenibacillus sp. 5A-101 stimulated root growth of 14-day-old seedlings. Inoculation of seeds with all studied bacterial strains mitigated adverse effects in wheat seedling leaves: the chl a/chl b ratio and proline levels were restored to those of the metal-free control, whereas flavonoid content decreased compared with non-bacterized plants grown under copper(II) chloride influence. These results confirm the potential of using stress-tolerant plant growth-promoting bacteria to enhance wheat tolerance to copper-induced stress. Keywords: chlorophyll, flavonoids, plant growth-promoting bacteria, proline, Triticum aestivum L.