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Print version ISSN 0102-0536
PEREIRA, Ricardo B et al. Carrot populations resistance to leaf blight with different levels of tropical germplasm. Hortic. Bras. [online]. 2012, vol.30, n.3, pp. 489-493. ISSN 0102-0536. http://dx.doi.org/10.1590/S0102-05362012000300022.
Leaf blight is responsible for significant losses on carrot production and the genetic resistance is one of the most efficient ways to control this disease. This study aimed to evaluate the resistance of carrot progeny populations to leaf blight with different levels of tropical germplasm. We evaluated the populations 561, 586 and 587 and, as control treatments, the commercial cultivars Juliana and BRS Planalto. We adopted the randomized block design, with two replications and plots consisting of 1.2 m2. The disease occurred naturally on the field and was evaluated each five days, beginning at 72 days after planting date. The populations 561, 586 and 587 and cultivar BRS Planalto presented similar and lower severities to Brasília and Juliana cultivars, which did not differ from each other. There were no significant differences in commercial and total root yield. In the analyses carried out between the progenies within each population and the control no differences were observed in commercial and total yield of roots. Regarding the severity, the progenies of the population 561 and 586 and BRS Planalto did not differ from each other and presented higher levels of resistance than Brasília and Juliana. However, one progeny of population 586 presented intermediate resistance. Ten of 15 progenies of the population 587 presented levels of resistance similar to BRS Planalto, while five presented resistance similar to Brasília and Juliana. This increased phenotypic variability indicates potential to obtain genetic gain for resistance to leaf blight. The commercial and total root yield of the populations 561 and 586 presented negative correlation with the severity of the disease. These results indicate that resistance to leaf blight is due mainly to tropical germplasm, observed in greater quantity in the population 561, of about 87.5%.
Keywords : Daucus carota; Alternaria dauci; Cercospora carotae; Xanthomonas hortorum pv. carotae.