Associação com Tuber spp. e/ou Trichoderma sp. em nogueira-pecã

Abstract

The Rio Grande do Sul plays a significant role in the production of pecan, accounting for approximately 70% of the national production. It also exhibits high potential for truffle cultivation, hosting around 90% of the processing industries related to this culture. The possibility of commercially co-cultivating truffles and pecan has been gaining traction nationwide since the discovery of Tuber floridanum, the first species found in Brazil, with the genus considered a delicacy in gastronomy. The objectives of this study were: a) to characterize the mycorrhization of two truffle species, Tuber aestivum and Tuber brumale, as well as the physicochemical properties of a pecan orchard, and b) to study the inoculation with Tuber floridanum and Trichoderma sp. in pecan seedlings. A historical survey and soil characterization of the pecan orchard located at UFSM were conducted. Chemical, density, and porosity parameters of the soil, which had been inoculated with Tuber aestivum and Tuber brumale in 2018, were evaluated. The identification of mycorrhizal associations with Tuber spp. and native ectomycorrhizae was performed. The percentage of mycorrhizal association in the roots was 15.58% with T. brumale and 13.33% with T. aestivum. The presence of ascomas under the canopy projection of pecan trees was not observed. In terms of physicochemical characteristics, the pH ranged from 6.3 to 6.8, phosphorus ranged from 157 to 304 mg/dm³, and potassium ranged from 268 to 360 mg/dm³. It can be asserted that Tuber spp. show potential for association with pecan plants. Another study was conducted in a greenhouse, testing the following treatments: Pecan without inoculation (T1), Pecan inoculated with T. floridanum (T2), with T. floridanum and Trichoderma (T3), and with Trichoderma (T4). The growth parameters of the seedlings and the colonization rate by ectomycorrhizae were evaluated. The total mycorrhizal percentages for the treatments were 45.37%, 74.47%, 68.33%, and 62.41% for T1, T2, T3, and T4, respectively. Trichoderma influenced mycorrhization rates and the root development of pecan. There was no significant difference in the height and diameter of the seedlings. Fungal inoculation did not influence the length of the primary root of pecan but altered the dry weight of the root due to secondary roots. Therefore, the use of Trichoderma with Tuber floridanum shows potential for the development of pecan seedlings."