Biofumigation Potential of Brassicas to Control White Rot Caused by Sclerotinia sclerotiorum on Eggplant

Abstract

This study aimed to examine the biofumigation effect of cabbage, broccoli and cauliflower against Sclerotinia sclerotiorum (Lib.), the pivotal agent of white rot in eggplant under in vitro conditions. Also, field experiments were carried out to assess the effects of brassicas on the disease severity index of white rot in eggplant and plant growth parameters in two successive seasons using a hybrid eggplant Darko F1 cultivar. Autolysis products of leaves and roots of the three brassicas plants were analyzed by gas-liquid chromatography-mass spectrometry (GC-MS). The results confirmed that the tested biofumigation plants led to a significant decrease in the mycelialgrowth and number of sclerotia formation of S. sclerotiorum under laboratory conditions. Cabbage meal was the most effective treatment, resulting in the most reduction in mycelial growth and sclerotia formation. Under field conditions, the incorporation of cabbage, broccoli and cauliflower plants into soil decreased the DSI of white rot during both seasons. This led to a significant increase in plant growth parameters, total fruit yield per plant and total fruit yield per feddan compared to control. Eight glucosinolates were identified by the natural autolysis of leaves and roots of cabbage, broccoli and cauliflower. The autolysis products as isothiocyanates, nitriles and epithioalkane nitriles were analyzed using GC–MS and referred to sinigrin, glucoiberverin, gluconapin, glucoerucin, gluconasturtiin, glucoiberin, glucoraphanin and glucobrassicin glucosinolates. The highest percentage of autolysis products was detected in cabbage roots. Other sulfur compounds and volatile oils with biofumigant activity were also detected in the three investigated plants.