Abstract
The purpose of this paper was to screen thirty-two arracacha genotypes for their reaction to root soft rot. Twenty roots of each genotype were inoculated with two Pectobacterium chrysanthemi isolates in a randomized experiment (10 roots/isolate). After inoculation, roots were individually wrapped with PVC film and kept at 26ºC in closed plastic bags. Soft rot lesions were recorded after 36 hours and genotypes were grouped in four classes of susceptibility by cluster analysis: 10 were less susceptible, 16 intermediate, 3 susceptible and 3 very susceptible. All the tested arracacha genotypes showed only variation in the degree of susceptibility.
Highlights
Resumo – O objetivo deste trabalho foi avaliar a reação de 32 genótipos de mandioquinha-salsa à podridão-mole das raízes
Arracacha (Arracacia xanthorrhiza Bancroft) is a typical South American vegetable root crop from the Andean region, which was probably introduced in Brazil at the beginning of the 20th century
The soft rot caused by Pectobacterium spp. in arracacha roots can cause losses of up to 100% in only three days (Henz, 2001)
Summary
Reaction of arracacha genotypes to the root soft rot caused by Pectobacterium chrysanthemi Gilmar Paulo Henz(1), Francisco José Becker Reifschneider(2) and Fausto Francisco dos Santos(1). The reaction of potato tubers to the three main pectolytic Pectobacterium was independent of the species/ subspecies chosen (Austin et al, 1988; Wolters & Collins, 1994), and the same was observed in carrot roots by Michalik et al (1992) In these papers, isolates of Pcc or Pchr were proven to be more aggressive at 22–30oC when compared to Pca. A similar approach was developed for the Pectobacterium × arracacha pathosystem, in which inoculation techniques, inoculum concentration, differences in isolate aggressiveness and methods of disease evaluation were studied (Henz, 2001). In the potato × Pectobacterium pathossystem, attempts to categorize the reaction of cultivars not always produced consistent results, probably due to problems such as the different inoculation techniques used, maturity of tubers, contamination of
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