Tuber and root resistance of potato genotypes against Meloidogyne chitwoodi in the presence of Avena strigosa, related to tuber quality

Been, Thomas H.; Molendijk, Leendert P.G.; Teklu, Misghina G.; Schomaker, Corrie H.


Relative tuber infestation and quality of two Meloidogyne chitwoodi resistant potato genotypes, AR04-4096 and 2011M1, were compared in glasshouse experiments at initial population density (Pi) = 16 second-stage juveniles (g dry soil)1 in the presence and absence of the bristle oat, Avena strigosa. When A. strigosa was added, Pfroot+soil (Pf= final population) on both AR04-4096 and 2011M1 increased 130×, Pftuber increased 1.9 and 3.7×, respectively, while Pftuber × fresh root weight (FRW)1 was the same. Nematode hatch from peel of AR04-4096, without A. strigosa, was delayed by 3 weeks but relative hatching rate was increased. Although the RStuber (RS = Relative Susceptibility) of both AR04-4096 and 2011M1 were lower than 1%, in the presence of A. strigosa tuber quality of 2011M1 dropped below the marketable level, while that of AR04-4096 was hardly affected. We conclude that: i) Pftuber is influenced by root mass; ii) root quality influences nematode hatch; iii) tuber quality is not an estimator for tuber resistance, and the reverse; iv) root resistance is equal to tuber resistance.