New tools for organic plant nutrition: microbial and aminoacid treatments for organic seed production of broccoli (Brassica oleracea var. italica Plenk.)

The amount and quality of organic seeds are the limiting factors for organic farming systems. The main objective of the H2020 BRESOV project (Breeding for Resilient, Efficient, Sustainable and Organic production) is to improve the quality of seeds for both phytosanitary and productive traits. Within this context, the effect of new plant nutrition treatments based on microorganisms and organic nitrogen on the quantity and quality of broccoli seed production was evaluated. We compared three different nutrition protocols (NP) containing mixes of 3KO® (Trichoderma Arzianum, T. asperellum and T. atroviride), Amminocomplex extra® (based on organic nitrogen), Stim root© (nitrogen, iron, zinc and carbon) and Kappa micro® (boron, iron, manganese, molybdenum and zinc) to a set of eight broccoli genotypes (GE) which includes two commercial F1 hybrids (‘Marathon’ and ‘Gentleman’) and six Sicilian landraces (‘Ciuriettu aprilino’, ‘Broccolo nero’, ‘Cavolo broccolo ramoso calabrese’, ‘Sparaceddu’, ‘Settembrino’, ‘Sanmartinaro’). The plantlets were transplanted in Adrano (Sicily) in August 2021 (4 plants m‑2) and were grown until the harvesting time of seeds. Plants were characterized for the flowering time and seed yield components. A significant interaction was observed between the NPs and GE for all seed yield components except for the main plant branches which differed significantly among the tested GE. The Sicilian landraces, ‘Broccolo nero’ and ‘Sparaceddu’ were the most performing landraces both for seed yield and quality compared to the commercial F1 hybrids ‘Marathon’ and ‘Gentleman’.