The indiscriminate use of synthetic fungicides has led to negative impact to human health and to the environment. Thus, we investigated the effects of postharvest biocontrol treatment with Debaryomyces hansenii, Stenotrophomonas rhizophila, and a polysaccharide ulvan on fruit rot disease, storability, and antioxidant enzyme activity in muskmelon (Cucumis melo L. var. reticulatus). Each fruit was treated with (1) 1 × 10⁶ cells mL⁻¹ of D. hansenii, (2) 1 × 10⁸ CFU mL⁻¹ of S. rhizophila, (3) 5 g L⁻¹ of ulvan, (4) 1 × 10⁶ cells mL⁻¹ of D. hansenii + 1 × 10⁸ CFU mL⁻¹ of S. rhizophila, (5) 1 × 10⁸ CFU mL⁻¹ of S. rhizophila + 5 g L⁻¹ of ulvan, (6) 1 × 10⁶ cells mL⁻¹ of D. hansenii + 1 × 10⁸ CFU mL⁻¹ of S. rhizophila + 5 g L⁻¹ of ulvan, (7) 1000 ppm of benomyl or sterile water (control). The fruits were air-dried for 2 h, and stored at 27 °C ± 1 °C and 85–90% relative humidity. The fruit rot disease was determined by estimating the disease incidence (%) and lesion diameter (mm), and the adhesion capacity of the biocontrol agents was observed via electron microscopy. Phytopathogen inoculation time before and after adding biocontrol agents were also recorded. Furthermore, the storability quality, weight loss (%), firmness (N), total soluble solids (%), and pH were quantified. The antioxidant enzymes including catalase, peroxidase, superoxide dismutase, and phenylalanine ammonium lyase were determined. In conclusion, the mixed treatment containing D. hansenii, S. rhizophila, and ulvan delayed fruit rot disease, preserved fruit quality, and increased antioxidant activity. The combined treatment is a promising and effective biological control method to promote the shelf life of harvested muskmelon.

Cucumis sativus L. plants are subjected to stress during production, affecting their growth, development, and fruit quality due to abiotic factors. Thus, the aim of this research is to evaluate Pseudomonas paralactis, Sinorhizobium meliloti, and Acinetobacter radioresistens plant growth promoting rhizobacteria (PGPR) effect on C. sativus plants under three substrate moisture levels (100, 75, and 50%). A randomized complete block design (RCBD) was used with an A x B arrangement: (1) factor A (inoculant) with four levels; (2) PGPR and control (without bacterium); (3) factor B (substrate moisture content) with three levels. Plant height, root length, and fresh weight increased by inoculating PGPR (121%, 135%, and 134%, respectively); likewise, these variables increased with higher moisture content (177%, 204%, and 234%, respectively), while the effect of the interactions of the PGPR and the moisture content in the substrate showed statistical differences in plant height increasing of 197% and root length of 267%. On the other hand, the content of phenols, flavonoids, and antioxidant capacity was statistically different (p ≤ 0.05) in inoculated plants, with PGPR increasing by 117%, 126%, and 150% respectively. In the moisture content of the substrate, statistical differences were observed, with an increase in the flavonoid content (114%) and antioxidant capacity (116%). The assimilation of nitrogen was higher by 274% and phosphorus by 124% with the PGPR inoculation, the moisture content increased the nitrogen content in the plant (257%) and the phosphorus content in plant (135%), showing significant differences (p ≤ 0.05). However, the interaction of PGPR and moisture content only presented statistical differences in nitrogen assimilation. PGPR can be considered as an alternative to obtain vigorous cucumber seedlings.

The soils of agricultural crops begin to suffer from arvenses and pathogens that are harmful to new crops after going through several production cycles. The chemical control of these pathogens is carried out through fumigants, which are applied at doses necessary to reduce the infectious potential at levels acceptable for crops. However, this may affect the biological, physical and chemical environment of the soil and, at the same time, the crops due to the toxic residues of these fumigants. In this work, the analysis of the pasteurization process of greenhouse soils sown with saladette tomato (Solamun lycopersicum) and cucumber (Cucumis sativus L.) was carried out, using water vapor for the pasteurization process at a temperature of 120 °C, obtained from a parabolic cylindrical solar concentrator (PCC), eliminating the use of boilers that conventionally require this method and use a lot of electrical energy, which increases the cost of the procedure and also causes the pollution of the environment. An experimental design was built for which tests were carried out at different steam emission times for each tomato and cucumber test soil. For each emission, it was necessary to reach 80 psi of pressure, with a steam exit time of a maximum of 160 s. Once this disinfection technique was applied, the presence of microorganisms such as Cladosporium sp, bacteria, pathogens and fungi was determined by various culture media. By means of this, the pathogens eliminated were verified, which were promoted by the process with respect to the test soil.