Banca de DEFESA: MARCOS PAULO CAVALCANTE FONSECA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARCOS PAULO CAVALCANTE FONSECA
DATE: 27/06/2024
TIME: 08:00
LOCAL: Sala 1 - PPGF
TITLE:

Phytosociological aspects of turnip greens (Raphanus raphanistrum) in brassica cultivation areas, interaction with Plasmodiophora brassicae and importance in the epidemiology of clubroot in Nova Friburgo, RJ

KEY WORDS:

Weed; survival spores; life cycle.

PAGES: 56
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitossanidade
SPECIALTY: Fitopatologia
SUMMARY:

The mountainous region of Rio de Janeiro, a major producer of brassicas, has intensive and sequenced cultivation in small family units. The limitations most cited by producers are pests and diseases, with clubroot, caused by Plasmodiophora brassicae, being one of the most frequent. It is a specific pathogen of the Brassicaceae family, biotrophic and able to survive in the soil. The widespread distribution of turnip greens (Raphanus raphanistrum), belonging to this same family, may be contributing to the survival of the pathogen and losses due to the disease. Having said that, the present work was carried out with the objectives of: a) evaluating phytosociological characteristics of turnip greens in brassica cultivation areas and the incidence of clubroot in turnip greens; b) evaluate the susceptibility of turnip greens to P. brassicae, the pathogen cycle in turnip greens and its possible role in its survival; c) evaluate spores, extracted from turnip greens, and their role in maintaining the pathogen cycle. The work was carried out in two stages, two collections of weeds in production areas in Nova Friburgo, RJ, and 3 tests, in a greenhouse at the UFRRJ Institute of Agronomy. Weed plants were collected in the months of February and August 2023. Species were identified, individuals were counted, dry mass was measured and phytosociological indices were then calculated. The susceptibility of turnip greens to P. brassicae, compared to cauliflower, arugula and turnip, was evaluated based on infection of root hairs and root cortex. Root hair infection was evaluated at 2 and 7 days after inoculation (DAI) with 2.4 x 10⁶ resistant spores per cm³ of sand. The assessment of cortex infection was assessed at 35 DAI with 4.8 x 10⁷ spores of the pathogen per cm³ of soil. The infectivity of spores extracted from turnip greens collected in the field was also evaluated, compared to those extracted from cauliflower via inoculation of cauliflower plants with 3.0 x 10⁶ spores per cm³ soil and evaluation at 35 DAI. Turnip green plants, identified as R. raphanistrum, were found in the summer and, mainly, in the winter, and with the presence of rudimentary galls. In the inoculation tests, the turnip plants showed infection of root hairs and the cortex and production of resistant spores, but at a lower incidence and severity than the three other species. Spores extracted from turnip greens were viable and efficiently infected cauliflower plants. It is concluded that turnip greens are a prevalent weed in the brassica production region and susceptible to P. brassicae and thus contribute to the survival of the pathogen in the region.

COMMITTEE MEMBERS:
Presidente - 1213072 - MARGARIDA GORETE FERREIRA DO CARMO
Interno - 1905333 - AROLDO FERREIRA LOPES MACHADO
Externo à Instituição - SILVALDO FELIPE DA SILVEIRA - UENF