Influence of Different Substrates and Nutrient Solutions on the Yields and the Incidence of Abiotic Disorders of Broccoli

Abstract

The incidence of different physiological disorders in broccoli in the Mediterranean areas is more frequent during the autumn and spring, the most important period for Spanish exportation of the fresh product. These disorders include brown bud, bud deformation, bracting and hollow stem, which adversely affect the quality of the product. They are related with cultivar sensitiveness but also with nutritional disorders and/or with different stressing factors. In the present experiment we wanted to deep focus on the better understanding the factors affecting the appearance of these disorders. Two nutrient solutions which varied in the potassium/nitrogen ratio, two growing media (perlite and coconut coir dust) and the foliar spray with calcium chloride, were tested in plants of the cultivar ‘Marathon’ grown in a greenhouse in containers in two irrigation regimes. With the low irrigation regime the low K/N ratio increased marketable yields and inflorescence weight but also increased the incidence of the disorders, mainly bud bracting and bud deformation. The type of substrate did not affect yield, but when plants grown in perlite, broccoli buds were more affected by the brown bud disorder. The foliar sprays with calcium sprays differently affect the incidence of the disorders, depending on the type of the disorder. With the high irrigation regime, the low K/N ratio also increased marketable yields and bud weight only in sprayed plants but no differences in the incidence of the disorders were found between nutrient solutions. Marketable yield and, only in sprayed plants, bud weight, were higher with coconut coir dust, and the incidence of brown bud was higher with perlite. Calcium sprays applications increased marketable yield, but also affect the disorders depending of the type. In general, marketable yield was higher with the high irrigation regime and the incidence of the abiotic disorders varied depending of the type: in low irrigation regimes was higher for bud deformation and bracting, but lower for brown bud and hollow stem.