Achnanthaceae diatoms

The Achnanthaceae family comprises a group of diatoms which, in an agronomic context, are classified as a biological contamination factor affecting hydroponic systems, aquaponic installations, and moist greenhouse substrates. These unicellular organisms are characterized by their silica frustules and their capacity for rapid proliferation under conditions of high light intensity and an excess of dissolved nutrients.

The primary impact of these algae is the formation of a dense biofilm coating on plant roots, nutrient delivery components, and hydroponic channel surfaces. While they are not parasitic fungi or bacteria, their presence physically blocks oxygen access to the root system, which subsequently triggers the development of secondary infections, such as root rot and oomycete pathogens.

The most frequently affected crops include leafy greens, lettuce, and tomatoes grown using Nutrient Film Technique (NFT) or Deep Water Culture (DWC) systems. Outbreaks of Achnanthaceae typically occur when lighting regimes are poorly managed, allowing direct exposure of nutrient solutions to light, or when there is an imbalance in phosphorus and nitrogen levels within the water.

The harmfulness of these diatoms lies in their competition for mineral nutrients and the physical inhibition of root hair growth. Mass algae proliferation often causes shifts in the pH of the nutrient solution, leading to sudden chlorosis and vegetative growth retardation, which significantly decreases crop quality and overall market value.

Protection and control measures require a comprehensive approach: regular nutrient solution replacement, light-proofing of reservoirs and channels, and the application of UV sterilizers. For effective prevention, it is recommended to maintain optimal pH levels and conduct thorough sanitation of equipment using hydrogen peroxide or certified algicides authorized for use in protected agricultural environments.