Green Navicula

Green Navicula (Navicula viridis) is a unicellular diatom alga that, in an agronomic context, is considered an agent of biofilm formation (algal infestation) within hydroponic systems, paddy fields, and waterlogged soils. It belongs to the Bacillariophyta division and acts as a significant factor in aquatic ecological dynamics.

This organism primarily affects crops grown in hydroponic systems, aquaponics, and flooded rice fields. In intensive farming, Green Navicula can proliferate on the surface of substrates or within nutrient solutions, hindering root gas exchange and competing with cultivated plants for essential mineral nutrients.

Symptoms of infestation appear as a brownish or greenish film on the surface of nutrient solutions, peat-based substrates, or damp soil surfaces. Unlike fungal phytopathogens, Navicula does not infiltrate plant tissues; instead, it creates a physical barrier, alters the pH of the habitat, and promotes the development of rot in the root zone.

The primary conditions for rapid reproduction are high light intensity, an excess of nitrogen and phosphorus compounds in the water, and stagnant water in nutrient delivery systems. This alga colonizes environments quickly at water temperatures between 15 and 25 degrees Celsius, making it a recurring challenge for closed-loop water systems in commercial greenhouses.

To mitigate the spread of Navicula viridis, the following measures are recommended:

• regular disinfection of hydroponic equipment;
• monitoring and controlling the pH level of the nutrient solution;
• shading water reservoirs to inhibit the photosynthetic activity of the algae;
• using ultraviolet sterilization systems for water filtration.