ABSTRACT Root-knot nematodes (Meloidogyne spp.) can cause a reduction up to 50% in the production of sugarcane (Saccharum spp.). Genetic resistance is considered an important component in the management of nematodes. Therefore, the aim of this study was to evaluate the susceptibility of 12 sugarcane genotypes when subjected to parasitism by Meloidogyne javanica and Meloidogyne incognita under controlled conditions in a plant growth chamber. Four experiments were carried out in randomized blocks with 12 treatments and four replicates for M. javanica and three replicates for M. incognita. The treatments were the sugarcane genotypes: RB966928 (susceptibility pattern), RB026842, RB036168, RB036145, RB036065, RB966229, RB036066, RB036068, RB046209, RB036163, RB036153, and RB036059. Each repetition consisted of a 2-L pot with previously autoclaved substrate (1:1 of sand and soil), and a pre-sprouted seedling was transplanted. From pure populations of M. javanica and M. incognita, approximately 2,000 eggs and eventual J2 were inoculated per pot. After 120 days, the final population of nematodes in the root and soil was counted using an optical light microscope and Peters slide, and the reproduction factor (RF) was calculated. Plants that presented RF < 1 were considered resistant, and plants that presented RF > 1 were considered susceptible. Among the 12 genotypes evaluated, 66% were susceptible to parasitism by M. javanica. The genotypes RB046209, RB036163, RB036153, and RB036059 were classified as resistant to M. javanica parasitism. For the species M. incognita, the susceptible genotypes represented 75% of the total, and the resistant genotypes were RB036163, RB036153, and RB036059. Rootknot Root knot spp. spp 50 Saccharum spp.. . Therefore chamber M RB RB96692 pattern, pattern , pattern) RB026842 RB036168 RB036145 RB036065 RB966229 RB036066 RB036068 RB046209 RB036163 RB036153 2L L 2 11 (1: soil, soil) presprouted pre sprouted transplanted 2000 000 2,00 J days slide (RF calculated evaluated 66 RB03605 75 total 5 RB9669 RB02684 RB03616 RB03614 RB03606 RB96622 RB04620 RB03615 (1 200 00 2,0 6 RB0360 7 RB966 RB0268 RB0361 RB9662 RB0462 ( 20 0 2, RB036 RB96 RB026 RB046 RB03 RB9 RB02 RB04 RB0

ABSTRACT Sugarcane-associated nematodes (Saccharum spp.) can reduce productivity up to 50%. Through the survey, it was possible to identify the main nematodes that occur in a certain region as a tool for designing the best management and control strategies. The aim of this study was to characterize the population of nematodes associated with sugarcane in the North Central, North Pioneiro and Northwest mesoregion of the state of Paraná, Brazil, quantify the nematode genera associated with the crop and identify the species of Pratylenchus and Meloidogyne. A total amount of 89 soil and root composite samples were collected in nine municipalities. Nematodes were extracted and counted in a Peters counting chamber under an optical light microscope. Morphological description followed identification keys. Pratylenchus spp. were identified by morphological characteristics; Meloidogyne spp. were identified by morphological characteristics and isoenzyme electrophoresis. Twelve genera of nematodes associated with sugarcane were identified: Pratylenchus, Meloidogyne, Helicotylenchus, Xiphinema, Mesocriconema, Trichodorus, Aphelenchus, Hoplolaimus, Tylenchus, Tylenchorhynchus, Ditylenchus, and Paratrichodorus. The genera Pratylenchus and Meloidogyne were found with the highest frequencies in the roots. Among the species of Pratylenchus, P. zeae and P. brachyurus were found, with P. zeae being the most frequent. Among the Meloidogyne species, only M. javanica was found. These results are essential to aid decision making in the management of phytonematodes, mainly in the development of new control strategies and in directing genetic breeding programs for development of sugarcane cultivars for the Paraná state.