2.4. Statistical methods
Results for all treatment replicates from trials 1, 2, and 3 were combined and one-way factorial analysis of variance was used, modeled as a regression using dummy variables, because of missing cells in the experimental design. Multiple mean comparisons (Fisher PLSD) were performed on sample data using StatView™ II (Abacus Concepts, Berkeley, CA). Unless otherwise stated, the significance level was 5%.