Penetration and development of Meloidogyne enterolobii in resistant and susceptible Capsicum spp.

The root-knot nematode Meloidogyne enterolobii is difficult to control due to its high aggressiveness and lack of resistant cultivars in the parasitized crops. Therefore, finding and characterizing sources of resistance to this nematode is an important task that may lead to new strategies for reducing its populations. The aim of the present study was to compare and describe the penetration and development of M. enterolobii in resistant and susceptible chili pepper genotypes (Capsicum spp.). Experiments were conducted under greenhouse conditions in a completely randomized design, in 2 x 5 factorial scheme, being factor A: two pepper genotypes (UFGCCH 24 - 'Bode Roxa' - resistant, and UFGCBA 3 - 'Cambuci' susceptible), and factor B: five periods of evaluation (7, 14, 21, 28, and 35 days after inoculation - DAI). The two genotypes were chosen based on a previous study that screened 72 Capsicum genotypes belonging to Universidade Federal de Goias (UFG) collection. UFGCCH 24 is from Capsicum chinense species (CCH) and UFGCBA is a Capsicum baccatum species (CBA). At each period the roots were washed, stained and evaluated for nematode penetration and life cycle stage. At 35 DAI the nematode population density and reproduction factor (RF) were also evaluated by extraction from roots. Second stage juveniles (J2) penetrated the roots of resistant and susceptible genotypes, although in a lesser number in the resistant. M. enterolobii had its life cycle delayed within the resistant genotype roots resulting in a lower number of specimens. At 28 DAI, fully developed females were observed in the susceptible 'Cambuci; whereas in the resistant 'Bode Roxa' at 35 DAI, nematodes with the appearance of J4 were still observed, and some individuals differentiating into males. 'Cambuci' showed RF = 1.82 and higher gall index and egg mass index compared to 'Bode Roxa' that had RF = 0.67.