Citrus rootstocks can exert some influences on fruit production and susceptibility of the plants to citrus canker (CC). This research was performed aiming to select rootstocks which induce higher productivity index and lower susceptibility of 'Monte Parnaso' navel orange (Citrus sinensis) trees to the bacteria Xanthomonas axonopodis pv. citri. The research was carried out in an experimental orchard, with ten-years-old trees, planted at spacement of 2.5m between trees and 6.0m between rows, located in Butiá city, in the Central Depression of Rio Grande do Sul state. It was used an randomized blocks experimental design, with 7 treatments and 4 replications. The treatments consisted of the following rootstoks: Rangpur lime (C. limonia.), 'Volkameriana' lemon (C. volkameriana.), 'Flying Dragon' trifoliata orange (Poncirus trifoliata), 'Caipira' orange (C. sinensis), 'troyer' citrange (C. sinensis x P. trifoliata), 'Sunki' tangerine (C. sunki.) and 'Swingle' citrumelo (C. paradisi x P. trifoliata). The parameters evaluated were: number of fruits and leaves with citrus canker lesions per plant and at two previously selected and marked branches per plant, at different times . The results revealed that the 'Swingle' citrumelo and 'Flying dragon' rootstocks induced the highest productivity index and, the lowest incidence of citrus canker disease on leaves and fruits. 'Rangpur' lime and 'Volkameriana' lime rootstocks, promoted a heavy crop load, however, showed higher susceptibility to citrus canker disease.
Citrus sinensis; Xanthomonas axonopodis pv. citri genetic resistance
