T. harzianum has been demonstrated to colonize maize roots
under axenic conditions. To assess whether T. harzianum colonizes
roots and persists under field conditions, we carried out an
experiment at Rovigo where evidence of a high percentage of
colonization at root emergence (GS 13; 86%) and at the post silking
stage (GS 65; 56%) was observed. (Fig. 1A).
Seed coating with T. harzianum T22 resulted in incremental root
colonization at GS 13 and GS 65, as demonstrated by comparing
roots colonized by indigenous T. harzianum in untreated seeds with
respect to treated seeds. Root colonization at GS 13 for both treated
and untreated plants remained stable over the years (Table 4;
P ¼ 0.1983 and P ¼ 0.2906, respectively) with higher values for
treated plants (Fig. 1A). This behavior was different at GS 65 with
colonization percentages for untreated plants that were similar to
those at GS 13 (P ¼ 0.1243), but a high variability was evidenced in
treated plants (P < 0.001).