In modern agriculture, fertilizers are commonly used to increase crop yields; however, their negligent use can lead to environmental pollution and the waste of essential nutrients such as inorganic phosphate (Pi). Encapsulated fertilizers are a feasible alternative that could prevent these issues, as they can protect Pi from leaching and extend the interval between applications. In this study, we developed and tested innovative fertilizers (IFs) manufactured with KH₂PO₄, encapsulated with chitosan modified via high-frequency ultrasound treatment. The characterization of these fertilizers consisted of Fourier-transform infrared spectroscopy analysis and scanning transmission electron microscopy to determine their sizes and forms. In addition, we evaluated the phosphate release profile using electrical conductivity. The IFs were spheroidal microcapsules with an average diameter of 0.5–2 μM and showed slow-release behavior. Their efficacy was assessed via in vivo and in vitro assays, using Arabidopsis thaliana as a study model. As expected, the IFs promoted the growth of seedlings. One of the IFs showed enhanced growth promotion, contrasting with the control. This phenotype was likely promoted by this fertilizer due to the synergistic effect of Pi and the modified chitosan used as an encapsulant matrix. Our results highlight the potential of these formulations, which have unique properties and could be used on a large scale.

Nowadays, agricultural research has not been only focused on studying the effect of different treatments on plant development and yield, but it has also been involved on study their effect on the postharvest quality of products. This study was conducted to determine the treatment effect based on plant growth-promoting rhizobacteria (Azotobacter chroococcum), alone or combined with different oligosaccharins of pectic origin (Pectimorf®) or derivatives of chitosan (Quitomax®), on the postharvest quality of zucchini fruits (Cucurbita pepo L.) var. 'Grey Zucchini'. Physical characteristics (polar and equatorial diameter, weight, dry biomass, f irmness, and color) and chemical characteristics (pH, total soluble solids, treatable acidity and vitamin C), proteins, antioxidant enzymatic activities (superoxide dismutase, catalase and total peroxidase), polyphenol oxidase activity, and antioxidant content (phenolic compounds and antioxidant capacity) were evaluated. Results showed significant differences (P ≤ 0.05) between control and treatments in most of the parameters evaluated, such as: color, length (up to 15.88%), width (up to 16.25%), weight (up to 57.31%), dry biomass (up to 34.43%), pH (down to 9.72%), vitamin C (up to 162.6%) and protein content (up to 22.38%), and total antioxidant capacity (down to 18.72%). Therefore, plant treatments improved the quality and composition of postharvest fruits, which accentuates the importance of organic treatments during the development of plants to obtain fruits with better organoleptic characteristics.