Which of the following biological agents is applied to seeds to reduce decay and disease?

• A. Bacillus subtilis
• B. Streptomyces aureofaciens
• C. Aspergillus niger
• D. Trichoderma longibrachiatum

Answer: (A)

Bacillus subtilis is known for its ability to produce various compounds that can suppress the growth of pathogens, thereby reducing seed decay and disease. This bacterium acts as a beneficial inoculant, promoting plant health by outcompeting harmful microbes and enhancing the plant’s natural defense mechanisms. Its effectiveness as a biological control agent is widely recognized in agricultural practices, where it is often used in seed treatments to protect against soil-borne diseases.

The other options, although they have roles in specific contexts, are not primarily recognized for seed treatment to reduce decay and disease in the same way. For instance, Streptomyces aureofaciens is used for its antibiotic properties but is less commonly applied directly to seeds. Aspergillus niger, while a well-known fungus in agricultural systems, often acts as a spoilage agent rather than a protector of seeds. Trichoderma longibrachiatum is beneficial for root protection but is not as commonly utilized solely for seed treatment purposes compared to Bacillus subtilis. Each of these biological agents has its functions, but Bacillus subtilis stands out specifically for reducing decay and disease in seeds.