EFFECTS OF SINGLE AND MIXED INOCULATIONS OF TWO VIRUSES ON GROWTH PARAMETERS OF SOME TOMATO CULTIVARS

Abstract

Worldwide, Tomato is an important vegetable in the diets of many consumers. However, its production is being hampered by many plant pathogens virus inclusive. To study the effect of two viruses on Tomato cultivars, Cucumber mosaic virus (CMV), genus Cucumovirus and Tobacco mosaic virus (TMV), genus Tobamovirus were mechanically inoculated separately and in mixed infections onto two tomato cultivars; F1 Mongal and Dankukumi D1 collected from the Tissue Culture Unit of Department of Crop Protection, Federal University of Agriculture, Abeokuta. Experimental design was a completely randomised design. There were four treatments namely: the buffer-inoculated controls, CMV-inoculated plants, TMV-inoculated plants and CMV+TMV-inoculated plants. For each treatment, there were two replicates with each replicate containing 4plants. In all a population of 48 plants per cultivar were inoculated. Leaves of plants were inoculated at 4 weeks old. Scoring of inoculated plants was done between 2 and 5 weeks after inoculation(WAI). Parameters scored were disease incidence, severity of viral symptoms, plant height, Stem diameter and number of leaves perplant. Symptoms observed on inoculated tomato cultivars included mosaic, mottling and necrotic lesions. Viral disease incidence for CMV-inoculated plants ranged from 25.0 % at 2weeks after inoculation (WAI) to 100.0 % at 5 WAI. Severity of viral symptoms expression for Tomato cultivar Dankukuimi D1 increased from 2.0at 2WAI to 4.0 at 5WAI respectively. In TMV-inoculated Tomato cultivars, increase in plant height of both inoculated and buffer inoculated controls was recorded from 2 to 5 WAI, however there was a significant(p<0.05) increase in the plant height of the healthy control of Dankukumi D1 cultivar over inoculated plants. No significant difference was observed in the plant height of both control and inoculated plants of cultivar F1 Mongal.