Resistance of tomato rootstocks to Meloidogyne arenaria and Meloidogyne javanica under intermittent elevated soil temperatures above 28 °C

Reproduction of Meloidogyne arenaria and Meloidogyne javanica on 12 tomato rootstocks and cultivars was tested to determine their relative resistance levels in a greenhouse with a non-temperature controlled environment. The nematode accumulated 754 and 719 degree-days (basal temperature 10 °C) in Experiment 1 (Exp. 1) and Experiment 2 (Exp. 2), respectively, but heat accumulation occurred more rapidly in Exp. 1 (65 days post-inoculation, dpi) than in Exp. 2 (88 dpi). Soil temperatures above 28 °C were recorded for 31 days during the experimental period in Exp. 1, and 20 days in Exp. 2. However, daily fluctuations in soil temperatures and intermittent peaks above 28 °C did not compromise the resistance provided by the Mi-1 gene, and thus rootstocks Morgan, King-Kong, and Unifort consistently expressed a high resistant phenotype to M. arenaria and M. javanica. In contrast, rootstocks Multifort and Maxifort expressed reduced resistance levels. The reproduction rate of M. javanica was significantly higher (P < 0.05) than that of M. arenaria on the resistant and susceptible genotypes except for on the susceptible Motril in Exp. 1.

► Intermittent temperature peaks above 28 °C did not affect the Mi-1 gene resistance. ► Tomato rootstocks Morgan, King-Kong and Unifort showed a high resistant phenotype. ► Meloidogyne javanica reproduced more than Meloidogyne arenaria on the rootstocks.