07-08-2013, 12:56 PM
Efficacy of Zanthoxylum armatum fruits against Alternaria alternata causing rot of tomato (Solanum lycopersicum L.)
ABSTRACT
Tomato (Solanum lycopersicum L.) is an important vegetable crop consumed worldwide as fresh, cooked or as various valued added processed forms. Out of the 15 vegetables listed by Food and Agricultural Organization, tomato ranks sixth in terms of total production. Owing to its large moisture content and water soluble nutrients, tomato fruit is highly perishable and susceptible to fungal rots. Some of the important rots of tomato fruit encountered in the markets are caused by Alternaria alternata, Phoma spp., Didymella lycopersici, Geotrichum candidum etc. Of the entire range of fungi that have been isolated as casual agents of tomato fruit rot, Alternaria alternata is a major storage decay agent. In order to reduce the pre and post harvest fruit losses, indiscriminate applications of fungicides have resulted in negative effects both in terms of production cost and risks to consumer’s health. In addition, rampant use of chemicals in plant disease management has led to the development of resistant races of pathogens. Keeping this in view, an ecofriendly attempt was undertaken for the management of Alternaria rot of tomato. Aqueous extract of Zanthoxylum armatum fruits was prepared at four test concentrations (25%, 50%, 75% and 100%) and its efficacy was checked as pre-infection dip treatment. Maximum control (66.97%) was achieved by using aqueous fruit extract of Zanthoxylum armatum at 75% concentration. Further, biochemical characterization of the fruits vis-à-vis superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPOX) corborates the results with respect to rot control. The activity of all three enzymes showed an enhancement in diseased tomato fruits as compared to healthy tomato fruits. Further application of aqueous extract of Zanthoxylum armatum fruits enhanced the activity of studied enzymes in the inoculated tomato fruits as compared to untreated tomato fruits. CAT activity showed an enhancement in Zanthoxylum treated fruits inoculated with Alternaria alternata at 50%, 75% and 100%. On the contrary, at 25% concentration there was a reduction in CAT activity. Furthermore, SOD and GPOX activity got increased at all applied concentrations. Thus, the present investigation stresses upon the use of ecofriendly botanicals in disease management instead of fungicides.