Using of Tamarind and Vanilla Essential Oils for the Management of Brown Rot Disease of Potato

Abstract

The hazard of chemical pesticides on the environment is a worldwide problem. Finding ecofriendly alternatives to chemical pesticides is a recent trend in agricultural research, one of the best choices is essential oils (EOs). This study aims to manage brown rot disease of potato using EOs. In vitro, Seven of 16 EOs inhibited Ralstonia solanacearum. The minimal inhibitory concentration (MIC) value was determined on R. solanacearum growth, tamarind and vanilla EOs had the lowest MIC (1%). Gas Chromatography-Mass Spectrometry analysis indicated that the main components of tamarind EO (TEO) and vanilla EO (VEO) are propylene glycol (50.97 %) and vanillin (40.78 %), respectively. TEO had a stronger bactericidal effect than VEO when R. solanacearum incubated in a solution of MIC of both EOs. In the pots experiment, soaking potato slices (spunta cultivar) in 1% of each of TEO and VEO for 30 minutes significantly improved peroxidase, polyphenol oxidase, chlorophylls and carotenoids, as well as, increased the plant height after 70 days of planting in comparison with the control treatment. Both EOs significantly decreased the disease rating from 4.2 in control treatment to 1.6 (TEO) and 2.2 (VEO). In addition to marked increments up to 36.11% (TEO) and 32.52% (VEO) in fresh tubers weight. After 60 days of tubers storage at room temperature, the two EOs decreased the infected tubers by 69.05% (TEO) and 47.17% (VEO). Generally, TEO showed better results than VEO. The growth inhibition of R. solanacearum and enhancement of physiological characters and yield of potato, encouraging the use of these two uncommon EOs as effective tools to manage brown rot disease of potato.