Biostimulants in organic vegetable nurseries: Study case in lettuce

In order to create better conditions to achieve food safety and sovereignty, agroecology, as a science, looks for solutions for several steps of the technical itineraries of the crops. Crop nutrition and protection are two main crop itinerary components that have been in the center of farmers challenges and consumers concerns, and biopreparations, which have been prepared using natural substances, have been used in agroecological systems, most times based on farmers empirical knowledge. Six biopreparations—purslane vinegar, prickly pear vinegar, orange fermented fruit juice, garlic extract, nettle infusion, and horsetail decoction—were used in this study, for physicochemical analyses and field tests in two different locations (Viseu and Castelo Branco, Portugal) in nurseries of Lactuca sativa L. (lettuce), and aimed to validate its results and uses. The nettle infusion presented the best stimulating results for the length of aerial part and the garlic extract presented the best results for the length of root, though there weren't significant differences and effects when compared with the control. The results indicate that the biopreparations used did not exert a biostimulant action in relation to the application of water in lettuce nurseries and that more research is needed to confirm the results observed by farmers.