Selection of resistant upland cotton genotypes challenged with aggressive isolates of Meloidogyne incognita race 3

Received: July 11th, 2022 ; Accepted: August 19th, 2022 ; Published: August 25th, 2022 ; Correspondence: cfurla@hotmail.comThis study aimed to select populations of M. incognita race 3 for screening cotton genotypes as part of a breeding program for the development of resistant cotton cultivars. Five isolates of M. incognita race 3, collected in Western Paraná, Brazil, were tested for virulence and aggressiveness against the cotton cultivars FM966 (susceptible), IAC 24 (resistant), CD 409, and FMT 701 (moderately resistants) under greenhouse conditions, and following a factorial design with five replicates. Thirty-one cotton genotypes were screened against the three most aggressive isolates of M. incognita race 3 tested before and kept under greenhouse conditions following a factorial design with five replicates. Experiments run under greenhouse conditions had single cotton plants inoculated with 5,000 eggs/J2 of M. incognita and were assessed at 120 days after inoculation considering the variables gall index, egg mass index, total eggs, and reproduction factor. The same genotypes tested under greenhouse conditions were also grown in a field infested with M. incognita race 3 in a randomized block design with 10 replicates. In the field, the M. incognita population was monitored by the quantification of J2 forms in soil samples collected before sowing, 60 days after sowing (DAS), and 120 DAS. A gall index score was used to evaluate the roots of cotton genotypes at 120 DAS. 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 resistance against M. incognita race 3 under greenhouse and field conditions