Reaction of Cotton Genotypes to Meloidogyne Incognita Race 3 and Selection Ofisolates With High Reproductive Rate in Cotton

Background: Among the pathogens that reduce cotton productivity in Brazil, Meloidogyne incognita is one of the most important as it causes severe yield losses and is widespread. The most recommended methods for control of this species are the use of resistant cultivars and crop rotation systems. In Brazil, M. incognita races 3 and 4 have already been reported as cotton parasites but the race 3 is the most commonly found and widely disseminated.This work aimed at selecting virulent and aggressive populations of M. incognita race 3 for testing sources of resistance to this nematode in cotton genotypes.Results: The three isolates of M. incognita race 3 were important for screening of resistant cotton genotypes. The isolate from Umuarama was the most aggressive followed by Moreira Sales and Iporã. The genotypes CD 05-419, CD 05-945, CD 05-1087 and CD 05-1170 showed good performance against M. incognita race 3 in both greenhouse and field conditions.Conclusions: The cotton genotypes CD05-945, CD05-1170, CD05-1087 and CD05-419 will be selected for future work involving tests for resistance against other important cotton pathogens. Those genotypes can also be used as source of genes for resistance to nematodes in cotton breeding programs. The search for virulent and aggressive M. incognita isolates was very important when screening for resistance in cotton germplasm.