Growth promotion of pecan rootstock seedlings with Trichoderma spp.

Abstract

The objective of this work was to select Trichoderma spp. strains with potential to promote the growth of rootstock seedlings of the pecan Barton cultivar by improving their morphological parameters and quality index, as well as to biochemically characterize these strains in vitro. In vitro bioassays were carried out with 59 Trichoderma spp. strains to evaluate their effects on the germination percentage and root growth of a bioindicator plant. The pre-selected strains were inoculated onto pecan seeds with a spore suspension at a concentration of 1x10⁹ conidia per milliliter. The experimental design was completely randomized, with five replicates. The analyzed variables were plant height, stem diameter, number of leaves, shoot dry mass, root dry mass, total dry mass, and the Dickson quality index. For each strain, qualitative evaluations of calcium phosphate solubilization and of the production of siderophores, hydrocyanic acid, and indole-3-acetic acid were carried out in vitro. The production of hydrocyanic acid and indole-3-acetic acid was not observed. Strains CPACT275, CPACT809, CPACT838, CPACT852, and CPACT859 significantly enhanced the biomass and quality index of ‘Barton’ pecan rootstock seedlings. The growth promoted by Trichoderma spp. may be related to calcium phosphate solubilization by all strains and siderophore production by CPACT838 and CPACT852.