Abstract:
The general objective was to evaluate the efficacy of Trichoderma species to promote the growth of tomato and to manage late blight disease under in vitro and in vivo conditions. A collection of 18 Trichoderma spp. were isolated from two commercial products (Trichotech® and Trianum-P®) that should have the antagonistic species Trichoderma asperellum and Trichoderma harzianum respectively. Cultural and molecular approaches were used to characterize the products. Differences on the growth rate and colony characterization including time of first appearance of green conidia and colony appearance were recorded on Potato dextrose agar and Rose Bengal media. Microscopy was done where the shape of the phialides, mass of conidia and branching of the conidiophores were observed. Displayed intra-specific variability related to Trichoderma spppremains within the limit of each species and the growth curve of Trichoderma spp. isolates was distinctive of species on PDA medium. Molecular characterization of the genomic DNA was done using ITS1 and ITS4 universal primers. Isolates that had a single PCR band pattern at 600bp were selected for sequencing. The sequences were aligned using the MEGA 6.0 software and the BLAST program NCBI. Multiple sequence alignment (MSA) was done using cluster W and phylogenetic tree was generated using Sea-view. A greenhouse 3×5 factorial experiment, arranged in a randomized complete block design (RCBD) with three replicates was also set to determine the efficacy of Trianum-P®, Trichotech® and their combination in controlling P. infestans and production enhancement of tomato plants. Tomato biomass, number of leaves and height were used to assess growth for 12 weeks at 3 week intervals. The data was subjected to ANOVA and the means tested by LSD. Cluster analysis of the data demonstrated two major clusters that is, A and B, Cluster A, consisted of Meyerozyma caribbica (GK9) while cluster B was further subdivided into three clusters. Sub clusters B1, B2 and B3 were T. asperellum, T. longibrachiatum and T. harzianum respectively. These clusters were supported at a bootstrap stability of 100% on the basal position. An inhibiting action was observed on the Phytophthora infestans mycelial growth of the isolates by the effect T. asperellum (82.9%), T. harzianum (71.5%) and the control was 0.0%. The greenhouse results showed that Trichoderma spp. strains reduced late blight of tomato plant by 6.6% (Trichotech® +Trianum-P®),12.7% Trichotech® and 17.2% Trianum-P®. Trichotech® resulted to an increase in tomato plant biomass thus significantly different compared to the other treatments
