DETECÇÃO DE FITOPATÓGENOS CAUSADORES DA PODRIDÃO-DO-COLO E REAÇÃO DE CULTIVARES DE FEIJOEIRO A COMPLEXOS FITOSSANITÁRIOS

Abstract

Cultivated bean is an important subsistence crop that is affected by agents both in the aerial and underground parts. The objective of this course conclusion work was to evaluate the identity of agents that cause collar rot, as well as the plant sanitary agents that affect the aerial part of common bean cultivars. In the 2017 harvest, 10 cultivars were grown, represented by BRS Executivo (cramberry©, Imperador©, Pérola©, Estilo©, Tangará©, F3F2©, Milênio©, Tuiuiu© and Uirapurú© and Campos Gerais©, cultivated in strips, separated by four blocks, were organized into 40 experimental units. Two collections of symptomatic plants were carried out, one in the vegetative stage (50 dap) and another in the reproductive stage (100 dap). A total of 18 symptomatic plants were analyzed in the vegetative reproductive stage and 29 plants in the reproductive stage. Tissues were subjected to water agar (WA) culture medium, after 48 hours for potato-dextrose-agar (PDA) culture medium. In the 2018 harvest, 28 bean cultivars were grown (using the same experimental organization as in 2017) where four evaluations (31, 47, 61 and 76 days after planting) of the plant sanitary severity were carried out, for later construction of progress curves, area under plant sanitary curve (AUPSC) and infection rate (IR), in addition to production parameters. In this test, all variables were submitted to parametric and non-parametric hypothesis tests. The plant pathogens detected that most affect the symptoms of cracking, wilting, yellowing and curling in common bean cultivars in the evaluated period were Fusarium oxysporum associated with the vegetative stage and Macrophomina phaseolina associated with the reproductive stage. The plant sanitary complexes in the cultivars evaluated on each day of evaluation show variations in terms of resistance to expressions. However, at the end of the evaluation period, the common bean cultivar IAC Sintonia showed statistically the lowest AACPF, being classified as the cultivar most resistant to the complexes of biotic and abiotic agents evaluated. On the other side of the reaction, it was observed that the cowpea cultivar BRS Tumucumaque was more susceptible to the attack of the evaluated agents. The resistant cultivars showed a peak of infection at 61 days after planting (DAP), with the maximum severity reached in cultivars considered resistant of 30% and susceptible to 43%. Due to the variability of the phenological stages, the drops in severity observed between 61-76 DAP are related to leaf loss and/or senescence for some cultivars.