Improving Trichoderma harzianum's Efficiency in Combatting Late Wilt Disease in Maize with Chitosan and Chitosan Nanoparticles.

In developing nations, maize (Zea mays L.) is a vital grain crop.
Magnaporthiopsis maydis is the fungus that causes maize late wilt, it is considered a
serious fungal disease in Egypt. El-Minia isolate-2 was the most virulent one on
Boushy cv. maize in vivo. M. maydis growth on PDA plates in vitro was strongly
reduced by chitosan and chitosan nanoparticles (chitosan-NPs) at 50, 100, 150, and
200 ppm. Trichoderma harzianum mycelium growth remains strongly unaffected by
chitosan concentrations from 50 to 150 ppm, while it decreases significantly at
concentrations up to 200 ppm. Transmission electron microscopy (TEM) showed that
M. maydis and T. harzianum mycelium cell membranes are structurally altered by
chitosan and chitosan NPs. TEM images of ultrathin slices showed M. maydis
mycelium with partial cell -wall lysis and membrane shrinkage. Chitosan NPs
damaged fungal cell walls and membranes, killing cells, while the non-treated control
had well-defined organelles. T. harzianum and chitosan nanoparticles at tested
concentrations (individually or in combinations) improved plant resistance to
pathogen and significantly reduced the disease incidance. Furthermore, these
treatments increased β-1,3-glucanase, peroxidase, and catalase enzyme activities in
maize leaves compared to both infected and uninfected control. In the 2024 growing
season, T. harzianum and chitosan NPs at 150 ppm were the most effective treatment
for increasing enzyme activities, mitigating late wilt disease, and improving maize
growth parameters and yield components at Gemmieza and Malawy Research
Stations.