Beneficial effects of plant growth-promoting yeasts (PGPYs) on the early stage of growth of zucchini plants

The use of microbes capable of beneficially interacting with plants is essential for advancing climate-smart agriculture. This approach aims to reduce chemical use while simultaneously enhancing crop productivity. This implies efforts to optimize the criteria for selecting potential plant growth promoters (PGPs), focusing also on yeasts, only recently investigated for their PGP potential. The present study employed a set of Ascomycetes and Basidiomycetes yeasts to test their PGP properties on zucchini (Cucurbita pepo L.), chosen as a fast-growing plant with a vast economical interest. Yeasts were tested alone and as consortium. Seed inoculation with yeasts boosted the early phase of growth of the zucchini plants, primarily affecting the root development. Three strains belonging to the species Schwanniomyces etchellsii, Zygotorulaspora florentina and Holtermanniella festucosa induced a strong and significant enhancement of weight and length of both epi- and hypogeal parts of the plant. Furthermore, the presence of yeasts induced strain-specific modulations in the biochemical profiles of soil, primarily detected in the rhizosphere. This suggests an active interaction between the roots and the inoculated yeast cultures.