Relative susceptibilities of five fodder radish varieties (Raphanus sativus var. Oleiformis) to Meloidogyne chitwoodi

Abstract

The fodder radish varieties Anaconda, Contra, Defender, Doublet and Terranova, known to have some partial resistance, were compared to the standard variety, Radical, to estimate their relative susceptibility (RS) for both population dynamic parameters of Meloidogyne chitwoodi and to evaluate P\ dependency. This approach must eventually lead to new screening methods for partial resistance tests. Plants were grown under controlled glasshouse conditions. Twelve densities of nematodes in five replications were used. Five plants per 7 1 pot were allowed to grow for a period of 11 weeks until their early flowering stage. Few seedlings of all the varieties at P\ = 32 and 64 J2 (g dry soil)-1 , and all seedlings exposed to the highest density, P\ = 128 J2 (g dry soil)-1 , died within a week after germination. Replanted seedlings developed into normal plants. Total yield, expressed as total fresh weight, was not affected by M. chitwoodi. A lower percentage of plants with galls was observed on partially resistant varieties as compared with Radical. For Radical, a maximum multiplication rate (a) of 0.38 and a maximum population density (M ) of 6.43 J2 (g dry soil)-1 were estimated. Radical proved to be a bad host for M. chitwoodi with all final populations lower than the P\. The parameter estimates of (M) for Anaconda, Contra, Defender, Doublet and Terranova were 0.011, 0.006, 0.027, 0.020 and 0.009 J2 (g dry soil)-1 , respectively. With Radical taken to he 100% susceptible, this resulted in RSm values of 0.17, 0.10, 0.42, 0.32 and 0.14% of these varieties, respectively, reducing high population levels of M. chitwoodi by more than 98%. There was no correlation between the rMgans and the RSm values, indicating that scoring the number of galled plants will not provide a suitable measure for partial resistance.

Effects of Cover Crops on Pratylenchus penetrans and the Nematode Community in Carrot Production

“…For example, sugarbeet cyst (Heterodera schachtii) and root-knot (Meloidogyne spp.) nematodes do not reproduce well on 'Defender' radish and it can be beneficial for control of these nematodes (Hafez and Sundararaj, 2009;Teklu et al, 2014). However, based on this study and others (Miller, 1978;Belair et al, 2002), radish is a host for Pratylenchus and may increase its population densities.…”

Damage thresholds and population dynamics of Meloidogyne chitwoodi on carrot (Daucus carota) at different seed densities

“…The managethe natural decline in time of M. chitwoodi in the absence of a host (Been et al, 2007). The yield loss and population dynamic models have been applied recently on potatoes (Norshie et al, 2011) and fodder radish (Teklu et al, 2014) subjected to M. chitwoodi. The yield reduction of a crop attacked by nematodes is the same for all tylenchid species, as demonstrated by Seinhorst (1998).…”

“…The population dynamics reported by Teklu et al (2014) revealed that the susceptible fodder radish, variety Radical, is, in fact, a bad host as it reduces population densities at every P i tested, although a new generation of M. chitwoodi could establish. Susceptible potato cultivars proved to be good hosts for M. chitwoodi (Norshie et al, 2011;Teklu et al, 2013).…”

Host suitability level of selected Brassicaceae plants for Meloidogyne arenaria (Neal) and Meloidogyne incognita (Kofoid & White) (Tylenchida: Meloidogynidae)

“…Köklerde tespit edilen yumurta kümeleri sayılarak 0-5 skalasına göre değerlendirilmiştir (Çizelge 2; Taylor & Sasser, 1978). Ayrıca, konukçuluk seviyesinin doğru şekilde değerlendirilmesi ve biyofumigasyon çalışmaları için uygun genotiplerin seçilebilmesi amacıyla denemeye alınan genotiplerin % RS (Relative Susceptibility= Test edilen bitkideki toplam nematod sayısı / hassas kontrol bitkisindeki toplam nematod sayısı x 100) değerleri belirlenmiştir (Teklu et al, 2014). Araştırmada incelenen özelliklerin, genotiplere ve kök-ur nematodu türlerine göre farklılıkların belirlenmesinde veri yapısına bağlı olarak tesadüf blokları deneme deseni (Two-way ANOVA) uygulanmıştır.…”