The Effects of Seed Inoculation with Bacterial Biofilm on the Growth and Elemental Composition of Tomato (<i>Solanum lycopersicum</i> L.) Cultivated on a Zinc-Contaminated Substrate

Abstract

Biofilm obtained from Bacillus subtilis subsp. spizizenii inoculated on vegetable seeds has been shown to have plant growth-promoting capacity. Seed inoculation with biofilm produced by this strain could also reduce the adverse effects on plant growth caused by soil or substrate heavy metal overabundance. Therefore, the objective of this work was to evaluate the impact of biofilm inoculated on tomato (Solanum lycopersicum L.) seeds, which were planted on a substrate with artificially added zinc. First, seeds of the Río Grande tomato variety were exposed to increasing zinc concentrations, namely: 50, 100, 200, and 400 ppm, with and without bacterial biofilm inoculation. Zinc addition and seed inoculation affected germination parameters. For example, an extra 200 and 400 ppm of zinc led to high toxicity. Biofilm inoculation, however, reduced the noxious effects of excess zinc, bringing acute toxicity down to moderate. Then, tomato plants growing from inoculated and non-inoculated seeds were cropped for 4 months in both substrates with 400 ppm zinc and without added zinc. Extra zinc addition significantly (p p B. subtilis proved to be effective as a bioinoculant to alleviate negative effects on tomatoes cropped in a substrate with excess zinc.

Keywords

• <i>Bacillus subtilis</i>
• biofilm inoculation
• zinc excess
• toxicity alleviation
• urban agriculture