Soilless Media Effects on Hot Peppers (Capsicum chinense Jacq.) Growth and Development and Root Colonization by Trichoderma

The existence of a healthy growing human population is reliant on the production of high quality food, feed, and fiber. This can be achieved by the use of intensive sustainable soilless cultures amended with symbiotic microbes. This study investigated the effects of Trichoderma on hot pepper (Capsicum chinense Jacq.) growth and root colonization at different phenological stages and on different growth media. A greenhouse study was conducted in a completely randomized block design with three treatments (control, Trichoderma harzianum (T22) and Trichoderma virens (GL13)) and three soilless media (perlite, coir, and coir:perlite) with four replications. Strains T22 and GL13 were grown separately on Biodac and applied to sterile Promix at the rate of 0.1% (v/v) at sowing of the seeds and applied to the soilless media at transplanting.  The following parameters were assessed: germination percentage, days to emergence, plant height, shoot and root biomass, yield, chlorophyll content, and Trichoderma population from the non-rhizosphere (day 7-21 post-inoculation) and rhizosphere (day 28-56 post-inoculation). The study was repeated twice. Results from experiment 1 indicated that Trichoderma treatment increased seedling height. Average Trichoderma population sampled from the non-rhizosphere was 6.2 and 6.3 log₁₀ CFU g^-1 for GL13 and T22, respectively. Trichoderma population sampled from the rhizosphere was 6.4 and 6.2 log₁₀ CFU g^-1 for T22 and GL13, respectively. In experiment 2, Trichoderma treatment decreased the days to emergence, and increased seedling height, shoot and root biomass, and chlorophyll content. Trichoderma population sampled from the non-rhizosphere was 6.3 and 6.4 log₁₀ CFU g^-1 for GL13 and T22, respectively. Trichoderma population sampled from the rhizosphere was 6.9 and 6.3 log₁₀ CFU g^-1 for T22 and GL13, respectively. Root colonization on the primary and secondary root system of hot pepper seedlings were significantly (p<0.05) greater in the Trichoderma inoculated plants than those of the control treatment. Plants grown in coir had significantly (p<0.05) greater height, shoot, and root biomass in both experiments than plants grown in perlite. Hot pepper fruit yield was significant (p<0.05) for plants grown in coir:perlite mixture in experiment 1. In this study, the application of Trichoderma on hot pepper seedlings demonstrated the improvement of seedling vigor and uniformity. Media type also influenced plant growth and root colonization by Trichoderma.