Compatibility of watermelon ( Citrullus lanatus ) cultivars with nematode-resistant wild Cucumis seedling rootstocks.

摘要

Watermelon (Citrullus lanatus) cultivars have no resistance to the southern root-knot nematode Meloidogyne incognita. Preliminary trials in Limpopo Province, Republic of South Africa, demonstrated that wild watermelon (Cucumis africanus) and wild cucumber (C. myriocarpus) were resistant to M. incognita race 2. A study was carried out to investigate whether the two Cucumis seedling rootstocks would retain their nematode-resistant capabilities to M. incognita race 2 when grafted with scions of highly nematode-susceptible watermelon cultivars 'Charleston Gray' and 'Congo'. Six treatment combinations were arranged in a completely randomised block design with 10 replicates. At harvest, 56 days after inoculation, the reproductive factor (RF=Pf/Pi) of M. incognita race 2 on grafted seedling rootstocks was lower (P<=0.05) than those on un-grafted watermelon cultivars. Generally, yield variables of grafted and un-grafted watermelons did not differ (P<=0.05). In conclusion, the two Cucumis seedling rootstocks did not lose their nematode resistant capabilities after being grafted to nematode-sensitive watermelon cultivars. The two Cucumis seedling rootstocks have the potential to serve as alternatives to methyl bromide in the management of M. incognita race 2 in watermelon production.