Enhancing sustainability of tomato, pepper and melon nursery production systems by using compost tea spray applications

Compost teas (CTs) are liquid organic formulates obtained by prolonged extraction, with or without aeration, of a quality compost into an aqueous medium. They can significantly improve plant growth and development likely through nutritive and/or biostimulant mechanisms. In nursery production chain of tomato, pepper and melon, the use of seven CTs was evaluated in order to substitute, totally or partially, chemical treatments with propamocarb-hydrochloride (47.3%) and fosetyl-Al (27.7%), a fungicide for the pathogenic oomycetes control. In general, CTs increased plant growth parameters, as suggested by measurements of root length (+9.1% and +8.1%, on average, on tomato and pepper, respectively), stem diameter (+12% on average, on tomato), number of leaves (+2.6% on average, on melon), and fresh biomass (+8.2% on average, on melon) in comparison with the chemical control. CT from artichoke and fennel composted residues have had the major impact on nursery performances of tomato, pepper and melon. After the first treatment of the polystyrene trays with the fungicide at sowing, our results indicated that CT may replace it in the following seedling production cycle, securing vegetative characteristics of nursery plants similar to the chemical control, that may incite fast starting of transplants in the field stage.