Does the pH of the suspension influence the germination of Trichoderma harzianum conidia?

Abstract

Fungi of the genus Trichoderma are important in phytosanitary management, presenting mechanisms that can be used for the biocontrol of plant diseases. To ensure the efficiency of biocontrol, it is important that the application conditions guarantee the development and competition of the antagonist. Therefore, the objective of this work was to evaluate the influence of pH on the germination of Trichoderma harzianum conidia. Tests were carried out to evaluate the germination of the fungus's conidia under different pH conditions. For this, citric acid-sodium phosphate buffer solutions with pH between 2.6 and 8.6 were prepared, and serial dilutions of the commercial product were performed until a concentration of 10⁵ conidia.mL⁻¹ was reached. Then, a conidial suspension was prepared in buffered medium (Buffer suspension + Tween 0.01%) with the desired pH, and maintained in suspension for 4 hours. A second test was also carried out to evaluate the effect of conidial germination on the pH of unbuffered medium. The data were subjected to Shapiro-Wilk normality tests and Tukey's test at 5%. Data on pH change over time were subjected to linear regression analysis. After analysis, it was observed that pH 4.6 provided the highest fungal germination, while at alkaline pH the fungus showed low germination. Acidification of the medium occurred due to the presence of conidia. The data indicate that pH is a determining factor in maintaining the biological activity of the antagonist, especially the pH of the application solution.