INFLUENCE OF TRICHODERMA AND SOIL SOLARIZATION ON STRAWBERRY YIELD

Abstract

Field experiments were conducted for three consecutive annual production cycles in Huelva (southwestern Spain) to evaluate the effectiveness of soil solarization and Trichoderma, alone and combined, in enhancing strawberry yield and the relationship between Trichoderma soil population, root colonization by Trichoderma, yield and root weight. A randomised complete block design with four replications was used. Each plot was 12.5 x 3.3 m and had three raised beds. Solarization was conducted during the summer, using clear 50 μm low-density polyethylene mulch. Trichoderma spp. were applied via drip irrigation and dip, adding to the soil 7-days before planting (10 8 conidia/m 2 ), and strawberry roots were dipped in a suspension of Trichoderma (10 6 conidia/ml) prior to planting. Solarization reduced Trichoderma soil populations. Nevertheless, Trichoderma soil populations increased over the three consecutive years in solarized plots, and no differences were observed after three repeated treatments of the same site. Combination of solarization with Trichoderma applications significantly increased Trichoderma soil populations relative to solarization alone, and root colonization by Trichoderma compared to the untreated control and the solarization alone treatment. Soil solarization, alone or combined with Trichoderma aplications, increased strawberry yield 77.6% and 78.2% in the 2 nd year, and 11.0% and 43.2% in the 3 rd year, respectively. Trichoderma spp. became established in soil, and by the end of each season it could be recovered from soil samples and from root segments. Trichoderma applications increased Trichoderma soil populations, root colonization, root weight and strawberry yield 84.9% in year 2 and 17.6% in year 3. Significant positive correlations were observed between Trichoderma soil populations and strawberry yield. Furthermore, Trichoderma soil populations and root colonization by Trichoderma were highly correlated.