Resistência de genótipos de pimenta-de-cheiro (capsicum chinense jacq.) à antracnose (colletotrichum brevisporum)

Abstract

Anthracnose is the most important disease of the “pimenta-de-cheiro” (Capsicum chinense), which can cause losses of more than 50 % of the production. The species C. chinense is widely cultivated by farmers in the Amazon and it is relevant in the State’s vegetable trade. It presents high genetic diversity and therefore, high potential for use in crop breeding. Ripe red fruits were obtained from fields the crop produced of peppers in the districts of Iranduba, Manacapuru, Rio Preto da Eva and Presidente Figueiredo. Experiments were carried out on seedlings (step I) and on detached fruits (step II). The first was conducted in greenhouse in a completely randomized design with 102 genotypes and four replicates. Seedlings were inoculated with INPA 2787 isolate (Colletotrichum brevisporum) at the concentration of 106 spores mL-1. At 7, 14 and 21 days after inoculation, disease severity evaluations were performed using scale of notes (1 = resistant to 6 = highly susceptible), and resistance genotypes were selected, which were taken to field. The fruits of 28 genotypes were harvested to proceed to the second experiment, which was conducted for two stage fruiting (immature and mature), with 15 replicates. The fruits were inoculated with the virulent pathotype and had their lesion size measured after 7 and 14 days. The results showed that lesion size in the immature fruits ranged from 0.3 to 9.7 cm2 and size in the mature fruits ranged from 0.2 to 9.9 cm2. The genotypes RPE41 and MPU 29 indicated resistance to anthracnose in both stages. Morphoagronomic characterization of fruits was also performed. There was variability for mass (5.58 to 13.74 g), length [C] (4.08 to 8.16 cm), diameter [D] (1.74 to 2.54 cm), and C/D ratio (1.88 to 4.70) of the fruit. In addition, a natural virus infection, transmission electron microscopy and molecular tests were identified in the peppermint leaves, confirming the presence of Cucumber mosaic virus and Pepper mottle virus, with transmission through the aphid vector of the species Aphis gossypii.