Banca de DEFESA: NEVENKA DE MATOS MOURA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: NEVENKA DE MATOS MOURA
DATA: 29/02/2024
HORA: 14:00
LOCAL: Sala de reuniões do Google Meet
TÍTULO:

Contributions to the study on the relation of Corynespora cassiicola with cotton and soybean seeds

PALAVRAS-CHAVES:

 Seeds. Cotton. Soybean. Corynespora cassiicola.

PÁGINAS: 123
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitossanidade
ESPECIALIDADE: Fitopatologia
RESUMO:

Corynespora cassiicola is the causal agent of target spots in cotton and soybeans and can be transmitted via seeds. This work was carried out to evaluate the relationship between C. cassiicola and cotton and soybean seeds, focusing on the transmission of these organisms from seed to plant and the effects resulting from this interaction. Two isolates of C. cassiicola were used to determine the transmission rate and assess the effects of the pathogens on the performance of cotton and soybean seeds/seedlings. Inoculation was carried out using the water conditioning method on the seeds of one cotton cultivar and one soybean cultivar, and their resistance or susceptibility to the pathogen in question was not reported. For cotton, the seeds were kept in the fungal colonies for periods of 36, 72, 108, and 144 hours, equivalent to the pathogen inoculum levels established for this study, with denominations: NI36, NI72, NI108, and NI144 respectively. In the case of soybean seeds, the seeds were in physical contact with the fungal colony for 36, 72, and 108 hours, equivalent to inoculum levels: NI36, NI72, and NI108, and a chemical treatment of the seeds with the product (Metalaxyl-M + Fludioxonil) was added to the experiment at the two inoculum levels: NI72 and NI108. The experiments were carried out in plant growth chambers at temperatures of 20 °C and 25 °C, and the effects were evaluated daily. The total transmission rate of each pathogen was calculated by adding up the pre-emergence death rate and the transmission rates with symptomatic and asymptomatic infection. The total transmission rates of C. cassiicola were directly proportional to the increase in inoculum levels, for both isolates and cultivation temperatures. About the physiological effects, germination and vigor (emergence speed index), initial and final stand, height and weight of fresh and dry plants, electrical conductivity and disease/damage index were evaluated, as well as the health test on seeds inoculated at the same inoculum levels used to evaluate pathogen transmission rates. It was observed that, for the two crops under study, the higher the level of initial inoculum in the seeds, the greater the negative effects on the quality of the inoculated seeds and the plants that came from them. Plants from seeds with NI144 inoculum level for cotton and NI108 for soybeans had the lowest values of ESI, plant stands, weights, and heights. The seed quality tests showed that the higher the inoculum levels, the lower the percentages of normal seedlings and germination, with the highest percentages of pathogen incidence in the seeds. Infected seeds also showed advanced degradation by electrical conductivity analysis. In evaluations of soybean seed performance, when chemically treated and untreated seeds were compared, seed treatment proved to be effective in reducing the level of inoculum and consequently produced better results. The use of the conventional PCR technique showed that asymptomatic plants carry the pathogen, which can manifest itself during the crop cycle.

MEMBROS DA BANCA:
Externo ao Programa - RAQUEL MARIA DE OLIVEIRA PIRES - DAG/ESAL (Suplente)
Externo à Instituição - MÔNICA CAGNIN MARTINS - NENHUMA (Membro)
Presidente - JOSE DA CRUZ MACHADO (Membro)
Externo à Instituição - ELLEN NOLY BARROCAS - NENHUMA (Membro)
Interno - CAROLINA DA SILVA SIQUEIRA (Membro)
Externo à Instituição - CARLA LIMA CORRÊA - NENHUMA (Suplente)
Interno - ANTONIA DOS REIS FIGUEIRA (Membro)