Phytonematodes Associated With Tomato (Solanum lycopersicum L.) and Screening of Tomato varieties and use of Coffee Husk for Management of Meloidogyne arenaria

Abstract

Nematodes are a costly burden in agricultural crop production. The root knot nematode is one of the most economically important plant parasitic nematode groups and is widely distributed and damaging tomato. The occurrence, biodiversity and distribution of nematodes in major tomato growing areas around Jimma, in particular to Dedo and Karsa districts were not conducted. Moreover, information on nematode management using host resistance and coffee husk amendments is unknown. The aim of this study was to assess the diversity of Phytonematodes associated with tomato production system in two districts and evaluate tomato varieties for their reaction to Meloidogyne arenaria and test coffee husk as an option towards management of M. arenaria on tomato. The survey was conducted at Dedo and Karsa district of Jimma zone. A total of forty composite soil samples and plant roots were collected from farmer’s field from eight kebeles. Fourteen tomato varieties (Moneymaker, Roma VF, Fetan, Melkasalsa, Metadel, Cochoro, Bishola, Gelila, Gelilema, APR d2 tomato, Chali, Margilobe, Melkashola and Miya) were tested for the reaction to M. arenaria and the effect of coffee husk application on M. arenaria was evaluated on three tomato varieties. The experiments were set using RCBD under greenhouse condition. Seedlings with four true leaves were inoculated with infective second stage juveniles a week after transplanting. Data on number of eggmass and root gall, gall index, final nematode population, reproduction factor, shoot height, fresh and dry weight, and root length and weight were collected after ten week of inoculation. ANOVA was done using SAS 9.3 version and means were separated using Lsd at p= 0.05. A total of nine nematode genera associated with tomato was recorded and identified viz. Meloidogyne, Pratylenchus, Helicotylenchus, Scutellonema, Rotylenchulus, Aphelenchus, Criconema, Cyst nematode (Globodera spp) and Paratylenchus. Meloidogyne, Pratylenchus, Helicotylenchus, and Scutellonema were the most frequently encountered genera (100%). Cyst nematode (Globodera spp) and Aphelenchus spp were detected and reported here for the first time from Ethiopia. The highest mean disease incidence was found from Babo kebele. Among tested tomato varieties, except Melkashola, all were found to be susceptible and have high numbers of eggmasses, root galls, final nematode population and reproduction factor. Variety Melkashola was identified as resistant host for M. arenaria with reproduction factor value of 0.14 at p<0.05. Application of Coffee husk reduced the reproduction rate of M. arenaria and enhanced the growth of tomato plant as compared to non-amended treatment. An increase in coffee husk proportion in treatment of combinations resulted in reduction of number of eggmass and root gall, final population and reproduction factor. The present study revealed that tomato was infested with several PPNs and both Melkashola variety and coffee husk were used as an alternative option to manage M. arenaria. However, the severe infections on tomato plants and growth impairment observed in the farmers’ field, calls for an immediate attention and implementation of feasible management strategies. Further studies are necessary to test this variety for more seasons to determine the durability of resistance and more attempts in coffee husk amendments are needed to confirm actual rates and timing of amendments and repeating the experiments under field condition to help us draw promising conclusion.