Abstract
Chili pepper has economic importance and is the dominant Solanaceae in the market of spicy spices. Among the pathogens that affect this crop, Meloidogyne enterolobii is one of the most important because it presents a wide range of hosts and there are no resistance genes identified that are efficient against this species. The present study aimed to evaluate the reaction of chili pepper genotypes (Capsicum spp.) to M. enterolobii in order to identifify genetic resistance. Three experiments were conducted in a completely randomized design under greenhouse conditions: Experiment I, with 53 genotypes with ten replications; Experiment II, with twenty genotypes with ten replications; Experiment III in a 16 × 4 factorial scheme, with sixteen Capsicum spp. genotypes and four inoculum concentrations of M. enterolobii and eight replications. Inoculation was performed seven days after transplanting the Capsicum spp. seedlings into 2L plastic bags filled with sterilized soil and sand (2:1), using 4,000 eggs + J2/plant. Ninety days after inoculation (DAI) (Experiments I and II) and 60 DAI (Experiment III) nematode population density, reproduction factor (RF), fresh root mass, egg mass index (EMI) and gall index (GI) were evaluated. Genotypes with RF < 1.0 were considered resistant according to Oostenbrink (1966). Thirty one genotypes of Capsicum spp. showed resistance to M. enterolobii with RF ranging from 0.87 to 0.08. Seventeen resistant genotypes of C. chinensis presented RF lower than 0.85, ten genotypes of C. annuum had the RF lower than 0.75, three genotypes of C. frutescens had the RF lower than 0.87 and only one genotype of C. baccatum was resistant to M. enterolobii, presenting RF = 0.6. EMI and GI weren’t considered reliable variables to determine resistance and susceptibility. Fourteen genotypes rated as resistant in Experiments I and II were submitted to increasing concentrations of inoculum and, nevertheless, remained resistant.
Highlights
The species of pepper of the genus Capsicum originate in the Americas and have been consumed for more than 7,000,000 years
At 60 days after inoculation (DAI) the roots were submitted to evaluations of egg mass index (EMI), gall index (GI), fresh root mass (FRM), nematode population density (Pd) and the reproduction factor (RF) as described above
The variables gall index (GI) and egg mass index (EMI) showed a great variation between genotypes in Experiment I and non-significant variation in Experiment II. These variables were not considered adequate for rating the genotypes as resistant or susceptible, following the Taylor and Sasser (1978) criteria. This because we found genotypes with low GI and EMI, that would be rated as resistant, but they were considered susceptible based on the RF according to Oostenbrink (1966) criteria
Summary
The species of pepper of the genus Capsicum originate in the Americas and have been consumed for more than 7,000,000 years They are grown around the world, with the largest producers being China, Thailand, South Korea, India, Japan, Mexico, United States, Brazil and Argentina (Rufino & Penteado, 2006; Pinto et al, 2011). Species of the Solanaceae family, especially chili pepper and sweet pepper (Capsicum spp.) and tomato (Solanum lycopersicum L.) are the most cultivated vegetables in the world and are highly susceptible to the jas.ccsenet.org. The use of tomato and pepper cultivars with resistance to M. incognita, M. javanica and M. arenaria is well established. The species M. enterolobii has been detected parasitizing tomato plants and peppers resistant to M. incognita, M. arenaria and M. javanica (Carneiro et al, 2006). This study had the objective to evaluate the reaction of pepper genotypes (Capsicum spp.) to M. enterolobii aiming identification of genetic resistance
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