Ecophysiological responses of the biocontrol agent Trichoderma atroviride (T-15603.1) to combined environmental parameters

The effects of temperature, water activity (aw), and nutritional status, and their interactions, on the radial growth rate (mm day−1) and lag phase of Trichoderma atroviride (T-15603.1), a strain with high biocontrol potential against wood-decay fungi, was monitored for 20 days on nutrient-rich (MEA) and nutrient-poor (LNA) media. Five levels of aw (0.998, 0.982, 0.955, 0.928, 0.892) were combined with five incubation temperatures (10, 15, 20, 25, and 30 °C). The growth rate dropped and the lag prior to growth increased as the temperature, aw and nutrient status of the medium decreased. T-15603.1 appeared to be more sensitive to aw reduction than to temperature or nutrient status. The use of response surface methodology to model the combined effects of these environmental factors on the radial growth rate of T. atroviride completed the experimental results and showed that the radial growth rate was particularly limited at low aw values on the nutrient-rich medium (MEA) and at incubation temperatures ⩾25 °C. Internal and external mathematical evaluations (RMSE,%SEP, Af, Bf, pRE) demonstrated that the model provides a useful and accurate method for predicting the growth rate of T-15603.1. This study should contribute towards a better understanding of the biocontrol efficacy of T-15603.1 in urban tree management.