Banca de DEFESA: MARIA TEREZA DE ALBUQUERQUE E NASCIMENTO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MARIA TEREZA DE ALBUQUERQUE E NASCIMENTO
DATA : 07/02/2025
HORA: 08:30
LOCAL: Sala 01 PPGFITO
TÍTULO:

FUSARIUM SPECIES AS A CAUSAL AGENT OF POST-HARVEST DISEASE IN WATERMELONS IN BRAZIL AND ALTERNATIVE METHODS OF CONTROL

PALAVRAS-CHAVES:

Pathogen identification, Citrullus lanatus, fruit rot

PÁGINAS: 84
RESUMO:

Watermelon (Citrullus lanatus) is the fourth most produced and exported fresh crop in Brazil, but one of the main limitations is the post-harvest diseases caused by microorganisms, which can generate losses of around 15%. In 2022, 65 watermelons cv. Harmonium (Basf®) were collected from the fields in the states of Rio Grande do Norte and Ceará, Brazil. The fruits were sanitized with 2.0% of sodium hypochlorite for 3 min, rinsed with water and then placed in a humid chamber at 25 ± 2°C and ≥ 85% humidity to induce fungal growth. After one week, 51% of the fruits showed lesions and mycelial growth, mainly in the peduncular region. Subsequently, small pieces (5 × 5 mm) of diseased tissues were placed on potato dextrose agar (PDA) and incubated at 25 ± 1 °C for 7 days. Isolates were obtained that presented abundant colonies of aerial mycelium, with color varying from white to dark orange or purple. The morphological characteristics allowed classifying the isolates as Fusarium spp. Nineteen isolates were selected for further molecular analysis. Through phylogenetic analysis and morphological characteristics, it was possible to identify 5 species from two different complexes, F. falciforme and F. suttonianum from the FSSC complex and F. pernambucanum, F. hainanense and F. sulawesiense from the FIESC complex. Koch's postulate was conducted on healthy watermelons from cv. Harmonium (BASF®), wounding the fruits with a sterile awl, discs of mycelium from 7-day-old plates were placed face down in wounds of equal diameter (8 replicates for each isolate). In control watermelons, the fruits were inoculated using only discs containing PDA. After 7 days of inoculation, at an ambient temperature of 25 ± 2 °C and in a humid chamber, white mycelium was produced from the inoculation points, followed by soft and sunken rot. The pathogens were reisolated and presented the same morphology as the inoculated isolates, closing the postulate; control fruits showed no symptoms. This experiment was performed twice and similar results were obtained. Two experiments were carried out to manage the disease, the first in vitro and the second one in vivo. For the in vitro tests, the mycelial growth of F. falciforme, the most present and aggressive found in previous tests, was measured in nine different products and 5 doses each (1 to 5% or mg.L-1), all of them included in the GRAS (Generally Recognized As Safe) list, including: Potassium Iodate (PI), Potassium Sorbate (PS), Sodium Benzoate (SB), Iodine (Io), Sodium Bicarbonate (SBC), Essential Oils of Fennel (EO Fe), Lemongrass (EO Lg) and Palmarosa (EO Pr), comparing the results with the synthetic post-harvest chemical registered for the crop in Brazil, Graduate A+® (Azoxytrobin + Fludioxonil) and control (water only). In the in vivo test, the products with the best in vitro test performance were selected. Five products: PS, SB, OE Fe, OE Lg and OE Pr were tested in 5 doses (1 to 5%) and compared with Graduate (1 to 5 mg.L -1) and control (distilled water only) in watermelons cv Ana® (Origene Seeds) harvested in a commercial area. Asymptomatic fruits were harvested and treated after 12 hours with the products and different doses, applying the products to the peduncular area. A DIC was conducted, with 10 fruits for each treatment and each fruit was kept in a humid chamber using polyethylene bags for 23 days in a cold chamber (10 °C ± 1.5 °C) and the incidence of the disease was measured at the end of the experiment. Graduate A+ was the best product tested, with 100% control of stem end rot in watermelons in all doses tested. SB and EO Pr had 90% control at doses starting at 4% and PS, BS, EO Lg and EO pr had 90% control at doses of 5%. Oil treatments had a negative impact, damaging watermelon tissues, especially at doses ≥ 3%. SB and PS, both salts were an interesting product and in larger doses can be used by producers as alternative products to prevent stem rot in watermelons.

MEMBROS DA BANCA:
Interna - ***.979.544-** - ANDREIA MITSA PAIVA NEGREIROS - UFERSA
Externa à Instituição - CYNTHIA PATRICIA DE SOUSA SANTOS ALVES
Externa ao Programa - ***.821.814-** - KAMILA CÂMARA CORREIA - URCA
Interna - 1544411 - MARCIA MICHELLE DE QUEIROZ AMBROSIO
Externa à Instituição - NAAMA JESSICA DE ASSIS MELO - UFERSA
Presidente - 1445570 - RUI SALES JUNIOR