Effect of inoculation with arbuscular mycorrhizal fungi on root-knot nematode (Meloidogyne incognita) in tomato cultivars

Abstract:

[Background] Root-knot nematode (RKN) disease is one of main factors constraining tomato production under greenhouse conditions in China. The arbuscular mycorrhizal fungi (AMF) contribute to the control of RKN and the growth of plant. [Objective] The effects of different AMF and combined inoculation on antagonizing the infection and propagation of Meloidogyne incognita were evaluated in two tomato cultivates differing in nematode susceptibility. [Methods] The two cultivars, one of which was susceptible cultivar (Monte Carlo) and the other (Xianke 1) was relatively resistant to root-knot nematode infection, were inoculated respectively by Acaulospora mellea (Am) and Rhizophagus intraradices (Ri) and the mixture of the two AMF species Ri+Am in the sterilized soil before inoculating root-knot nematode, Meloidogyne incognita. The growth of plants and the suppression to nematode infection were investigated. Furthermore, the tomato “Monte Carlo” was inoculated with the mixture of AMF and transplanted in the continuous cropping field soil infested by RKN to evaluate the effects on the growth of tomato and the protective effects against RKN. [Results] The mycorrhizal efficiency of Monte Carlo to inhibit nematodes was greater significantly than that of Xianke 1. Different AMF treatments had different inhibition effects on nematodes. The cultivar of Monte Carlo inoculated by the mixture of two AMF species Ri+Am showed higher protective effects than any single AMF inoculation treatment, while Xianke 1 inoculated by Ri was higher than other treatments. The infection of nematode also greatly influenced AMF colonization, especially to the cultivar Xianke 1. But the AMF colonization of most treatments was still up to 70% in harvest time, except for the species of Am. The tomato “Monte Carlo” inoculated with the mixture of Ri+Am significantly reduced the number of galls and egg masses of RKN in the continuous cropping field soil containing Meloidogyne incognita, comparing to the controls. [Conclusion] The colonization of the mixture of AMF alleviated the infestation of the nematode disease of tomato better than single AMF colonization to a certain degree. The protective effects of susceptible cultivar inoculated with AMF against nematodes were greater than those of the resistant cultivar to nematode.