Characterization of Thyme and Tansy Extracts Used as Basic Substances in Zucchini Crop Protection

Abstract

Bio-sourced substances used for crop protection in natural and organic farming have a positive impact both on human and environment health: plant extracts are effective to stimulate plant defense against pests and diseases, with no toxic effect and they could be classified as basic substances. The chemical characterization of thyme and tansy extracts were carried out with ICP and NMR techniques for the analysis of elemental content and organic components. Antioxidant activity was evaluated by DPPH method. Phytostimulant effects of extracts were evaluated on zucchini crop in a preliminary field test. Vegetative plant conditions were assessed by measuring the chlorophyll content. The 1% extracts were chosen for field trial because of their maximum antioxidant activity (over 80%) and their cheapness compared to 2% concentration. NMR showed that the spectrum of tansy highlighted the phenolic fraction in 6-9 ppm region and, in particular, at 5.9 ppm the signals of thymol, a peculiar antioxidant compound; while the spectrum of thyme is less significant. The field trial results showed a higher fruit yield and a positive effect on plant growth in treated plants respect to control ones, due to the composition and antioxidant activity of both plant extracts. In fact, thyme extract treated plants showed a yield equal to 6,4 kg per plant, higher than no treated ones, 5,1 kg per plant; also tansy extract induced a higher yield respect to control plant, respectively 5,6 and 3,9 kg per plant. The results obtained indicate the role of the extracts investigated as basic substances.