Masters Theses
Date of Award
12-2024
Degree Type
Thesis
Degree Name
Master of Science
Major
Plant Sciences
Major Professor
David Butler
Committee Members
Kellie Walters, Bonnie Ownley
Abstract
Beneficial soil fungi, like Trichoderma spp. isolates, can parasitize structures of plant pathogenic fungi, solubilize poorly-soluble soil nutrients such as phosphorus (P), and induce crop resistance to plant pathogens, however, little information exists on the magnitude of Trichoderma benefits for plant health and production. This study evaluated eight native Trichoderma isolates—T. afroharzianum, T. arundinaceum, T. asperelloides, T. asperellum, T. hamatum, and several T. harzianum species complex isolates—for ability to reduce Fusarium oxysporum f. sp. lycopersici (Fol) and to solubilize forms of soil P (aluminum or calcium phosphates). This work was conducted as four separate objectives and we hypothesized that effects of Trichoderma on Puptake and reduced wilt incidence caused by Fol would vary among indigenous Trichoderma isolates and tomato germplasm across a tomato domestication gradient and significant correlations would be a result of Trichoderma-induced effects on P-uptake and disease reduction in tomato. Chapter 2, objective 1, assessed the ability of eight Trichoderma isolates (T1 to T8) to reduce Fol in tomato (Solanum lycopersicum cv. Valencia). Trichoderma treatments increased biomass and reduced disease symptoms compared to controls; T3 and T5 were most effective. Objective 2 assessed Trichoderma potential to solubilize secondary P compounds in Pikovskaya’s (PVK) broth and competitive interactions with Fol in lab assays on PVK agar. Isolate T8 showed the highest biomass in P-deficient conditions, and isolates T5, T6, T7, and T8 exhibited competitive interactions with Fol on aluminum phosphate. In Chapter 3, Objective 1, Trichoderma isolates T3 (T. arundinaceum) and T5 (T. harzianum) were screened for the potential to solubilize soil P and increase crop uptake in genetically diverse and varying domesticated tomatoes. The effect of Trichoderma on P uptake was limited and varied by tomato genotype and P source. In Objective 2, the impact of Trichoderma (T5) on P solubilization and Fol resistance was studied in genetically diverse tomatoes. Trichoderma improved aluminum phosphate solubilization, and tomatoes with aluminum phosphate fertilization showed greater resilience and lower disease ratings. This research concluded that the effectiveness of Trichoderma in improving crop growth and disease resistance depends on the soil chemical environment, Trichoderma isolate traits, and tomato genotype.
Recommended Citation
Dalton, Caitlin Priscilla, "Roles of native Trichoderma isolates in reducing tomato Fusarium wilt and increasing phosphorus uptake. " Master's Thesis, University of Tennessee, 2024.
https://trace.tennessee.edu/utk_gradthes/12821
