Effect of silicon in the nutrient solution on the incidence of powdery mildew and quality traits in carosello and barattiere (Cucumismelo L.) grown in a soilless system

Carosello and barattiere are herbaceous landraces belonging to the species Cucumis melo L. These landraces are grown in and consumed throughout the Puglia Region of southern Italy as unripened melons and are appreciated in place of cucumbers due to their improved quality profile. There are serious difficulties in the use of chemical disease control methods for these landraces due to frequent and long periods of harvest. The aim of this research was to study the effect of the application of silicon (≤ 3.6 mM potassium silicate) in the nutrient solution on the yield, quality, and sensitivity to powdery mildew of carosello and barattiere plants. Carosello showed a higher sensitivity to powdery mildew than barattiere. A supply of silicon reduced the severity (3.3% vs. 29.5%) and incidence (49.1% vs. 81.5%) of powdery mildew on both carosello and barattiere, compared with non-Si-fed control plants. The relative water content of leaves was higher in Si-treated plants, without changes to membrane permeability. Carosello proved to be more productive than barattiere (6.0 vs. 2.2 kg fresh fruit per plant, respectively). Among the qualitative parameters measured, total soluble solids and dry matter contents were higher in barattiere than in carosello fruit (4.0° Brix and 4.95 g 100 g-1 FW vs. 3.6° Brix and 4.81 g 100 g-1 FW, respectively). The silicon content of Si-fed carosello fruit was twice that of control fruit; whereas, the Si content of barattiere was not influenced by Si treatment.