CHLORIDE LEVELS
A similar, yet often misdiagnosed, issue stems from the
cucumber plant’s sensitivity to chloride. Chloride uptake by
cucumber plants accumulates in the foliage, producing a
band of pale green tissue around the leaf margin, followed
by scorching and browning of the edges.
Cucumbers need a good-quality water supply that doesn’t
contain high sodium chloride (common salt) levels. Sodium
chloride can be a common problem in many water supplies
and where domestic water softener units are being used,
and recirculating systems are particularly more prone
to chloride buildup when sodium chloride is present in
the water supply. The use of an alternative water source
or reverse osmosis is a good option to clear things up. In
addition, avoid using fertilizers and nutrient products that
contain potassium chloride and calcium chloride.
“
DUE TO THE rapid and prolific nature of fruit
production, cucumbers have a particularly
high requirement for potassium, much of
which ends up in the fruit tissue and plays
a role in flavor, firmness, shelf life, and
overall compositional quality.”
CUCUMBER NUTRITION
Cucumber nutrition is like that of other heavily fruiting
crops, with an emphasis on the use of vegetative and
fruiting formulations as the plant moves through the
different growth stages. Due to the rapid and prolific
nature of fruit production, cucumbers have a particularly
high requirement for potassium, much of which ends
up in the fruit tissue and plays a role in flavor, firmness,
shelf life, and overall compositional quality. Potassium
also affects stress resistance, plant turgor, and osmotic
control. However, deficiencies can be common in
recirculating systems with heavily fruiting cucumber
crops. The recommended potassium levels during
fruiting are 200-350 ppm. Using a potassium booster or
aggressive bloom nutrient products usually provides
these levels. Calcium levels are also essential during
this phase and should be boosted as the first fruit are set.
Boron is another common nutritional problem with
cucumbers. Plants deficient in this nutrient develop fruit
that has cavities or is hollow in the center. Young fruit
may also drop from the plant, have corky markings or
yellow streaks on the skin, or develop a curved shape,
while newer leaves may become distorted. Recommended
levels of boron in the nutrient solution are 0.5-0.8 ppm.
SYSTEM SHARING
While it’s common for an indoor garden to have a
number of different plant species sharing the same
recirculating nutrient solution and system, cucumbers
can place a particularly high demand on oxygen and
certain nutrients. They also produce large amounts
of organic root exudates. This may require a higher
frequency of solution replacement, additional methods of
oxygenation, and regular monitoring, as well as keeping
a check on potassium levels during the fruit phase.
Maximum Yield USA | December 2016
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