An investigation into root-knot nematode (Meloidogyne javanica) control in tobacco (Nicotiana tabacum L.) using four Kutsaga seeds varieties, monitoring the population seasonal dynamics

Abstract

Use of Tobacco (Nicotiana tabacum L.) resistant varieties in plant parasitic nematode management programs has been increasing in developing countries including Zimbabwe. Resistant varieties provide both economic and sustainable benefits for smallholder farmers who dominate the tobacco industry in Zimbabwe and produce their tobacco under continuous cultivation. A field trial was conducted at the Tobacco Research Board (TRB) during the 2014-2015 growing season to evaluate the effects of varietal resistance on Meloidogyne javanica galling index and populations. Four Kutsaga seed varieties, KRK 26, T70, T75 and KM10 were grown on land that was continuously cultivated with susceptible variety (KM10) for 3 seasons. Treatments were laid in a split plot design in four blocks. The untreated controls were fumigated crops with ethylene dibromide. Soil sampling from plots with tobacco varieties was done and bioassays were conducted using Tomato (Solunum lycopersicum L.) to determine the number of egg masses produced. Significant differences were observed across all results. Results on egg masses indicated that KRK 26, T70 and T75 managed to produce egg masses index less than 2 at P<0.01. Destructive sampling was done and results showed significant differences at P<0.01 on which T70 and T75 had a gall ratting less than 2 while KRK 26 had a gall rating above 2. Fresh leaf weights obtained from destructive sampled plants indicated that T70 and T75 had higher cumulative weight gain during the season. Varietal yield functions (total and saleable) were observed and results showed that T75 followed by T75 produced higher yield at P<0.01. Final root galling index was assessed and results highlighted that T70 and T75 had a gall rating less than 2. Both T70 and T75 exhibited resistant characteristics on meloidogyne javanica and produced a better crop than KRK26.