Effect of Some Seed-Borne Fungi on Seed Germination and Seedling Vigor of Wheat, and Biological Control of the Pathogens

Abstract

Seed-borne fungi have a significant effect on seed germination and seedling vigor in wheat. The aim of this study was to assess the impact of 23 pathogenic and growth promoting seed-borne fungal isolates on wheat seed germination and seedling vigor, both in vitro and in vivo, in addition to evaluating the potential of some biocontrol treatments against the aggressive isolates in the lab and in the greenhouse. The findings indicated significant variability in the effect of the fungal isolates. Bipolaris sorokiniana (28A) was the most aggressive isolate and significantly exceeded all other treatments in pathogenicity. It completely inhibited seed germination in vitro and produced the highest disease severity index, resulting in severe retardation of seedling growth in vivo, followed by Aspergillus nidulans and Alternaria alternata. Several Alternaria spp., Aspergillus spp., and Fusarium verticillioides exhibited significant pathogenic effects. On the other hand, some isolates, particularly Alternaria infectoria, had positive effects on seedling vigor as they exhibited a low disease severity index. The results obtained suggested that seed-borne fungi exhibited a wide range of biological interactions, from pathogenic to beneficial, highlighting the importance of assessing disease severity in addition to seed germination. Among the biocontrol treatments evaluated, Bacillus subtilis alone and in combination with Trichoderma harzianum were the most effective in reducing disease severity caused by Bipolaris sorokiniana (28A) and Alternaria alternata (50C). These treatments also resulted in significant improvements in seedling growth parameters. The findings of this study provided valuable insights into seed health management and contributed to the development of effective strategies for the control of seed-borne diseases.

Keywords:

Fungal diseases, Triticum aestivum, biological control, seed-borne fungi, Iraq.