Comparative evaluation of Raphanus sativus var. lobo defense efficiency against Contarinia nasturtii using foliar application of sodium selenate, ionic silicon form and garlic extract

Relevance. Contarinia nasturtii Keiffer is one of the most dangerous insect pests of Brassicaceae plants dramatically affecting plant yield and seed productivity.Material and Methods. The effect of single foliar application of sodium selenate, ionic form of silicon (Siliplant fertilizer) and garlic extract on the efficiency of Raphanus sativus lobo defense against Contarinia nasturtii infestation was evaluated in condition of greenhouse. Concentrations of the applied reagents were: sodium selenate 26.4 mM; Siliplant – 1 ml/l; garlic extract – 8 g/l. Seed productivity and C. nasturtii infestation levels under Se, Si and garlic extract administration under infestation were determined along with the analysis of plant antioxidant status and sugar content.Results. Foliar application of Siliplant singular or in combination with Se provided the highest seed productivity and mass of 1000 seeds. Plants treated with Si, garlic extract and Si+Se demonstrated lack of C. nasturtii infestation only a week after the preparation supply. Contrary, selenate provided less pronounced defense. Among biochemical parameters tested the values of the total dissolved solids were the highest in plants treated with Se and Se+Si. Changes in the intensity of plant defense due to garlic, Se and Si supply were reflected in the increase of the total phenolic content compared to the values typical for control plants and in a significant accumulation increase of disaccharides, participating in tissue recovery after herbivory attack. Silicon application also provided an increase of selenium accumulation by lobo leaves.