|
Environment plays a very important role in plant
growth upto a point. Once optimal environmental
levels have been achieved in the hydroponics grow
room, however, it is the quality of nutrition that
determines crop quality and output. The following
background information will be useful in
understanding of the role of
hydroponics nutrients
Nitrogen
Plants absorb nitrogen from fertilizers in both
Nitrate (NO3) and ammonium (NH4) forms. Both
ammonium and nitrate forms are available in the
standard fertilizer mix supplied. It should be noted
however, that ammonium levels should be
significantly lower than nitrate levels with a safe
level being 10 to 20 times nitrogen available in the
Nitrate form vis-à-vis the Ammonium form.
Ammonium is readily available to plants and can
build up to toxic levels in plant tissue if it is
not assimilated for growth. Besides, the Nitrogen
from Ammonium is difficult to leach away once it is
in plant tissue. It is therefore important too
ensure that ammonium content in the nutrients is
carefully regulated.
Over supply of fertilizers with high levels of
Ammonium nitrogen manifests as distorted and dark
growth starting at the plant’s growing tip. The
imbalance may also lead to symptoms of other
nutrient deficiencies despite these nutrients being
supplied in the correct amounts. This is because of
the nutrient imbalance that is created. Higher
nitrogen levels are required during vegetative/green
growth phases. After proper rooting of cuttings,
nitrogen levels can be increased from ¼ strength to
full strength over 10 to 14 days. Over application
of nitrogen causes delayed flower and fruit
development. Nitrogen levels at the time of rooting
of cuttings should be around 100 ppm and may be
increased to +250 ppm for aggressive growth under
optimal conditions. Light conditions can make a
difference to the Nitrogen to Potassium ratio, which
can be about 1:1 under higher light conditions,
while under low light conditions it may be as high
as 1:5.
Phosphorus
Plants require the phosphorus content of the
nutrient mix to be high during the
flowering/fruiting phase of their life cycle. At
other times amounts between 15 to 30 ppm are quite
adequate for most crops. Over supply of phosphorus
will be harmful during these stages as it will lead
to imbalances of iron and calcium and even zinc.
Iron and zinc have an association with the greenness
of plants, phosphorus levels should therefore be
increased only with corresponding increases in
levels of calcium, iron and zinc. Calcium levels
should be maintained at 1.5:1 ratio with phosphorus.
Most commercial calcium nutrient formulations
include the right proportions of trace elements to
cover flowering/fruiting requirements. Phosphorous
levels may be increased to 250 ppm during the peak
phase maintaining important ratios such as calcium
and micro-nutrients.
Potassium
Potassium is required in root development and also
for the ripening process of flowers, fruits, and
seeds. Potassium levels can be increased during the
flowering/fruiting phase to harvest a heavy,
colorful and firm produce. High potassium levels in
some crops help increase resistance foliar diseases
such as powdery mildew.
Under low lighting growth conditions higher
potassium to nitrogen ratios in the range of 3:1
helps healthy vegetative growth. Under brighter the
same nutrient proportion may be closer to 1:1 to
stimulate vigorous green growth. Most plants do well
on potassium levels in the range of 100 to +400 ppm.
Calcium
Calcium is an important component of the cell walls
of plants and is also plays an important role in the
processes of cell division. It requires to be
maintained in a ratio to phosphorus and is best
applied in greater amounts 1.5X the level of
potassium. The calcium magnesium ratio is also
important and should be maintained at 3:1. For
instance with 150 ppm calcium levels in a nutrient
solution, magnesium levels should be maintained at
around 50 ppm.
Magnesium
Magnesium is associated with keeping the plant
“green” and is a carrier molecule for certain plant
processes. Indoor crops will generally benefit from
elevated magnesium levels. Reports on the use of
elevated levels of Magnesium have been positive with
growers harvesting firmer flowers and fruits.
Hydroponics
calcium formulations often contain additional
amounts of magnesium. It should be noted however,
that magnesium levels should be maintained around
1:3 ratio to calcium.
Other Nutrients
In addition to the above nutrients, that constitute
the main macro-nutrients that plants need to obtain
from the nutrient formulations, there are other
macro and micro-nutrients that are vital to various
plant processes. While plants use macro-nutrients in
large or appreciable quantities, the micro-nutrients
are required in trace amounts Plants absorb carbon,
hydrogen and oxygen from the air and water. The
following table lists various nutrients essential
for plant nutrition and the different plant
processes they serve.
Macronutrients
Carbon--> Organic compounds formation
Oxygen--> Energy release
Hydrogen--> Water formation
Nitrogen--> Chlorophyll, Proteins formation
Phosphorus--> Photosynthesis
Potassium--> Enzyme activity, starch formation,
sugar formation
Calcium--> Cell growth, component of cell wall
Magnesium--> Enzyme activation
Sulfur--> Amino acids and proteins formation
Micronutrients
Boron--> Reproduction
Chlorine--> Root growth
Copper--> Enzyme activation
Iron--> Photosynthesis
Manganese--> Enzyme activation
Sodium--> Water movement
Zinc--> Enzymes and auxins component
Molybdenum--> Nitrogen Fixation
Nickel--> Nitrogen Liberation
Cobalt--> Nitrogen Fixation
Silicon--> Cell wall toughening |
