Oxifertigation and Foliar Nutrient Contents of Closed Soilless Rose Crop

Abstract

Oxygen diffusion in soilless culture systems in Mediterranean climate conditions is often quite low, especially in summer. This fact is seldom taken into account even though it could lead to plant development constraints, as for instance scarce root development or certain nutrient uptake deficits. A study of a rose crop in a soilless recirculating system with oxifertigation and nightly oxygen supply has been carried out to determine whether there is a cause-effect relationship between the production and growth increase in soilless culture systems which have been supplied with oxygen and the plant metabolism optimization due to the absorption of different nutrients. One and two years old cv. Red Corvette plants were planted in containers with two substrates (perlite B6 and A13). They were grown with or without diurnal oxifertirrigation and with or without night oxygenation in a 2x2x2 factorial experiment. A robot automatically controlled fertirrigation, lixiviated disinfection, nutrient solution recomposition from lixiviates, watering and fertilize. Nutrient solution was continuously held with oxygen over saturation. Night oxygen supply was done directly into the substrate by sequent pulsations. Nutrient content on leaves and petioles were determined using: ion-sensible electrode (nitrogen); Bray-Kurtz colorimetric method following by a spectrophotometer (λ=660nm) (phosphorus); flame photometry (potassium) and atomic spectroscopy analysis (iron, calcium and magnesium). Differences in foliar mineral contents were observed between two produced fluxes: Moreover, calcium and magnesium leaf content was also higher in plants grown in A13 perlite substrate. Foliar nutrient’s content in oxifertigation treatments were only different in potassium and calcium. They were significative upper in diurnal oxifertigation plants. Significative differences did not appear either in the rest of elements or night oxygen supply conditions. Calcium foliar content increase with diurnal oxifertigation treatment ant this happens with any of the nocturnal treatments. Increase in potassium foliar content in oxifertigation treatment is bigger with nocturnal oxygen supply in B6 substrate, possible because of its long woody life with important nutrient’s stocks and its harvest time (earlier phases of flower development).