Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DATA: 30/06/2023
HORA: 13:00
LOCAL: Anfiteatro do departamento de fitopatologia

Understanding pitfalls and proposing strategies to optimize the biological control of white mold (Sclerotinia sclerotiorum) in soybean


Sclerotinia sclerotiorum, cultural and biologic practices, network meta-analysis, endophyte

GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitossanidade
ESPECIALIDADE: Fitopatologia

White Mold management is based on the integration of cultural, chemical, and biological practices. Cultural management and biological control are effective tool to tackle the disease. In the first part of the study, we present a literature review addressing the contribution of both strategies in the management of white mold. Also, it was shown the integrated use of biocontrol agents in non-host crops to the pathogen and the possible benefits of this practice in the soybean crop production systems. For the second part of the study, we evaluated during seven crop seasons, 74 uniform field trials conducted throughout Brazil to assess the performance of biological control products on the reduction of the carpogenic Sclerotinia sclerotiorum sclerotium germination. The reduction in carpogenic germination (mean difference; MD) by three products classes (Trichoderma, Bacillus and Mixed) was summarized using a multilevel network model (59 trials, k = 340). Separate network meta-analysis was then performed to determine the influence of three classes (low, moderate, and high) of average monthly temperature (AMT) and average monthly rainfall (AMR) on biocontrol performance. The result of the first metanalysis are all three product classes significantly reduced carpogenic germination, with fitted  values of -10.6270 for Bacillus, -8.5928 for Trichoderma, and -7.0177 for Mixed. For (AMT) and (AMR), only interactions of genus and low or moderate AMT and AMR were statistically significant from zero (p < 0.1), indicating that high AMT and AMR affected biocontrol of carpogenic germination. For the second chapter We evaluated carpogenic germination, colonization and crop yield, either on soybean or succeeding crops (Wheat and Maize) in a double factorial design (treatment x crop) and their interaction. Here, we found soybean carpogenic germination rates from 31.00 to 61.6 %, (P = 0.583). Colonization from 4.7% to 19.4% (P = 0.174). Also, biological and chemical application disease incidence (P = 0.520), range from 73.7% to 87.2% and yield production from 2001 to 2803kg/ha. For carpogenic germinationno interaction (crop x treatments) effect was observed (P=0.328).The treatments reduced (P=0.011), the germination control rate was 65.7% and decreased by treatments up to until 47.0%. The effect of the Crop factor (p=0.022), maize germination rate by 59.6% and wheat by 50.3%. Evaluated colonization, we found effect by treatments, (P=0.157), crop (p<0.001) and interaction (crop x treatment) (p=0.048). Colonization in maize trials range from 2.2 % to 10.1 %. Highest colonization was observed by Trichoderma asperellum A, follow by Trichoderma harzianum, Trichoderma asperellum B, and Bacillus a. + Trichoderma h.  by 10.2 %, 9.9%, 2.7% and 2.2%, respectively. Wheat colonization rates from 16.6 to 39.8%. Trichoderma asperellum B, followed by Trichoderma harzianum, Trichoderma asperellum A, Bacillus amyloliquefaciens + Trichoderma harzianum  by 39.8%, 24.4%, 21.0% and 16.6%, respectively. Wheat yield production (p=0.177) and Maize yield (p=0.593). Thus, these results suggest that biological applications in wheat crop have more possibility to help contribute to decrease Sclerotinia sclerotiorum initial inoculum. The last part of our study, we investigated that effect of dressing-seed by Trichoderma sp. to biological agent can growth endophytically on wheat plants by qPCR and microscopy light. Evaluated dressing-seeds effects on development length of roots and aerial parts at 7 and 20 days after planting by Student's t-test. Additionality, analyze viability of Trichoderma persist on tissues after Glyphosate finalized wheat plants and ability to colonize sclerotia of Sclerotinia sclerotiorum. At the 7th day after planting shoot (P = 0.318) and root (P = 0.054), however at 20th day after planting, for aerial parts (P=0.049). Plants treats with Trichoderma sp. increased shoot length by 10,7%. Additionally, root length (P = 0.008) increased by 18,7%. Trichoderma mycelium grew trough the parenchyma roots cells and into leaf tissues on the basis of the leaf hair and epidermis. The high T. asperellum levels detected on roots at 20 days after planting up to 1 x 10 5.  Followed by roots at 7 days after planting up to 1 x 10 4. For shoots at 7 and 20 days, up to 1 x 10 3. After wheat plants were treated with glyphosate, the presence of T. asperellum decreased to 1 x 10 3 root, and to 1 x 10 2 in the bottom leaf Regarding carpogenic germination (P = 0.419), we found germination rates were similar for the control (31.2%) and Trichoderma (26.7 %). Thus, there is a parasitism of sclerotia by biocontrol products confirmed and its stability and improved efficacy can be improved considering the dominant wheather (rainfall and temperature) and cover crop (wheat). In turn, wheat may serve as a crop to selective buildup the population of the antagonist.

Externo à Instituição - CAMILA PRIMIERI NICOLLI - UARK (Membro)
Externo ao Programa - JOSE MARIA VILLELA PADUA - DAG/ESAL (Membro)
Externo à Instituição - PABLO SCHULMAN - UFG (Suplente)
Externo à Instituição - LINDSEY CHRISTINE SLAUGHTER - TTU (Membro)
Externo à Instituição - JOSIANE BARROS CHIARAMONTE - ESALQ (Membro)
Notícia cadastrada em: 15/06/2023 15:32
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