Growth, Health, Quality, and Production of Onions (Allium cepa L.) Inoculated with Systemic Biological Products

The efficiency and consistency of biologicals in the field remain a drawback of current conventional products. The development of systemic biological products has opened a new avenue for microbiological and agricultural research. In this study, we evaluated over a two-year period (2022 and 2023) the functioning of two systemic products, a biofertilizer and biofungicide, on the performance of the onion. The first indicator of proper functioning of these products in onions was reflected in increased chlorophyll accumulation. At the end of both years, the inoculated plants were taller, heavier, and developed more leaves than their control counterparts (p < 0.5). Inoculated onion bulbs collected at harvest time were significantly heavier (45.1% in 2022 and 56.2% in 2023) than their non-inoculated counterparts (p < 0.5). Onion quality, expressed in terms of total soluble solids and pyruvic acid content, was also significantly improved in plants inoculated with the biological products; the two-year average values for these quality variables were 10.2 vs. 14.4°Brix and 2.3 vs. 4.0 µmol∙g^-1 for control and biologically treated plants, respectively. The two-year average fungal incidence was 1.9 times greater in the control group than in the inoculated plants, while the average onion yield for this period was 44.7% higher (p < 0.5) in the biologically treated plot (54.7 t∙ha^-1) than in the control one (37.8 t∙ha^-1). Based on comparisons with previous studies employing conventional biologicals, our results demonstrate the superior effectiveness of the systemic biologicas in improving onion performance.