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The quarantine nematode, Meloidogyne chitwoodi, is a growing threat in arable crop production. Considering its polyphagous nature, introducing resistance to cash and green manure crops is one of the strategies to manage this nematode. Dutch potato breeders are successfully introgressing resistance to their cultivated potatoes. Since 2010, Wageningen University started the “MeloResist” project to evaluate the partial resistance of these genotypes and to develop a standard methodology to test the degree of partial resistance. Several aspects of the relative susceptibility of these genotypes, containing a single resistance gene against M. chitwoodi, were studied in 4 consecutive experiments. Six potato genotypes, including two genotypes with resistance to potato cyst nematodes (Globodera pallida) were tested for their partial resistance in 10 kg pots. Two of these genotypes were then selected to investigate the possibility to downscale the partial resistance test to smaller pots. Potato genotypes were grown for 14 -16 weeks in 10, 5, 3 and 2 kg pots in an artificial soil. The potato cv. Désirée was used as a susceptible control. Initial nematode densities (Pi), expressed as J2 (g dry soil)-1, consisted of 2 log series: 2x , x ranging from -3 to 7. The final population density, also expressed in J2 (g dry soil)-1, was measured by extracting and counting nematodes from roots and soil. A meta-analysis was carried out, which included data from Norshie et al, (2011). Population dynamics, yield loss and quality models were used, their parameters and variation estimated and the relative susceptibility was calculated. The parameter estimates of the population dynamics, the maximum multiplication rate (a) and the maximum population density (M), were inversely related to pot size. The potato genotypes showed a very high resistance to M. chitwoodi with RS values between 0.04 and 4%. Two genotypes, with non-M. chitwoodi resistance genes, were either susceptible or had moderate partial resistance (RS > 58%). RSa and RSM values of the genotypes tested were not always the same. Quality of tubers was also extremely improved and significant tolerance was observed on the tuber yield with increased nematode densities as compared to cv. Désirée. Overall, RS testing in a 3 kg pot at a density between 8 and 16 J2 (g dry soil)-1 seems possible. Below and above these densities problems occur. At low densities RS estimation is too variable because of the low numbers of J2 that can be retrieved, while at Pi values above 16 J2 (g dry soil)-1 plant growth of the control, cv. Désirée, is reduced resulting in lower Pf values and an underestimation of the partial resistance.
|Publication status||Published - 2015|
|Event||4th Symposium of Potato Cyst Nematode Management (including other nematode parasites of potatoes), Newport, UK - |
Duration: 7 Sep 2015 → 8 Sep 2015
|Conference||4th Symposium of Potato Cyst Nematode Management (including other nematode parasites of potatoes), Newport, UK|
|Period||7/09/15 → 8/09/15|