Ameliorative Effects of PGPB on Yield, Physiological Parameters, and Nutrient Transporter Genes Expression in Barattiere (Cucumis melo L.)

The intensive application of chemical fertilizers to overcome deficiency of nutrients and achieve maximum agricultural productivity has led to environmental impacts. A significant strategy for sustainable management, by decreasing the use of chemical fertilizers, can consist in the technology based on suitable levels of fertilization in combination with plant growth-promoting bacteria (PGPB) inoculation. This work aimed to test in vivo a consortium of three PGPB, previously isolated and characterized in vitro, on Barattiere plants (Cucumis melo L.). Plants were grown in a soilless system at the commercial dose of mineral fertilizer and at half dose, in order to evaluate the effects of these microorganisms on plant physiology, yield, and the transcriptional expression of four genes involved in NH4+ (AMT2), Fe (FRO, IRT1), and Pi (PHT1) transport and uptake by plant. Our results indicate that even in a soilless pot experiment, where a mineral nutrition solution is used, the bacterial consortium of PGPB improves fruit yield and early maturity, some physiological parameters, and upregulates the expression of some key genes related to N, Fe, and Pi plant nutrition, remarking the environmental and economic gains deriving from the use of half dose of mineral fertilizer.