Algae: Friend or foe?
Could Some Algae Be Beneficial?
While the negative effects of algae growth in hydroponics are fairly well-known and it is generally
accepted as being a nuisance and potentially toxic
for plant growth, there is another side to algae that
is still under investigation. Certain types of algae
can be beneficial. One example of this is the giant
brown algae species, also known as seaweed, extracts
of which have been developed for horticultural and
hydroponic use as plant growth supplements and
organic fertilizers. Some researchers have even found
that certain algae species release growth promoters in plant cultivation systems. Among these plant
growth regulators are auxins, cytokinins, gibberellins,
abscisic acid and ethylene. Other researchers have
found that certain algae can produce anti-fungal and
anti-bacterial compounds that might assist with disease prevention in the root zone. These types of trials
generally found that while overall heavy algae growth
in hydroponics has negative effects on crop growth,
there exists the potential to identify certain algae species that produce beneficial compounds and isolate
these for use in soilless systems. In the future, we
could see extracts from beneficial algae (apart from
seaweed products) being a routine supplement in
hydroponic nutrient solutions used for plant growth
promotion and control of root diseases.
Apart from the potential of beneficial growth
compounds extracted from some algae, common
everyday algae species growing in a hydroponic
nutrient solution do in fact give off oxygen during
photosynthesis. In heavily populated solutions,
small bubbles of oxygen might be seen being
Top left: Long, thin filaments of algae remain attached to the
growing channel base.
Top right: Dense, black algal growth releasing oxygen bubbles
as a result of photosynthesis.
released from the algae under good light conditions. However, while oxygen is released into the
nutrient solution by live algae, once algae bloom
then die, they then consume dissolved oxygen
and can add a large volume of organic carbon
into the system, which, in a solution culture,
needs to be avoided.
Where Do Algae Come From?
Hydroponic gardeners often wonder how this
green scourge finds its way into a previously clean
system and nutrient solution. Algae are widespread in the natural environment and are an
efficient and rapid colonizer anywhere there is
moisture, light and nutrients for growth. Algae are
common in many water sources such as rivers and
streams, ponds, lakes and rainwater storage tanks.
Treatment of city water supplies usually destroys
most of the algae present, and while that might
slow the development of an algae bloom, it only
takes one algae spore in the water supply to start
an outbreak. Algae spores are everywhere and are
usually dispersed in soil or water, or on plant or
organic material. They also travel on wind currents, in the air, mixed with dust or are transported
via living carriers including insects, animals and
humans, thus making them impossible to avoid.
“Certain types of algae can be beneficial.
One example of this is the giant brown
algae species, also known as seaweed.”
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Maximum Yield USA | February 2014