June 2021 - 21

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Keep Up With Your K
It's for good reason that we
attach importance to the role of
potassium in plant nutrition -
and fruit in particular, says Dean
Konieczka, consultant agronomist
with OMEX®
Agrifluids USA.
Did you know that potassium is
responsible for, or plays a part in,
more than 60 different biochemical
pathways within the plant? Vital
for photosynthesis, essential for
protein synthesis, it also has major
function in regulating the opening
of leaf stomata - the site of plants'
respiratory and water regulation.
Intricately associated with the
movement of water, nutrients and
carbohydrates - the products
of photosynthesis, plants also
rely on potassium for enzyme
activation. In particular, potassium
affects production levels of a
key compound called adenosine
triphosphate (ATP). ATP is
instrumental in the regulation of
photosynthesis.
It's no surprise then, that when
potassium supplies are challenged,
plants respond: reduced yields,
poor quality produce and greater
susceptibility to damage from pests
or diseases.
In fruit production especially,
potassium is crucial in increasing
the levels of vitamin C and sugar,
improving their flavor and color,
and encouraging growth -
resulting in large fruits. And it's
not just while the fruit is on the
But it doesn't stop there. Potassium
also increases drought resistance,
through improved root growth and
structure, a major consideration
as we begin to experience more
unpredictable patterns in weather,
and farmers come under increased
pressure to improve water-use
efficiency.
So what's the best way to ensure
your fruit crop gets a healthy dose
of potassium? While there's often
plenty of potassium naturally
occurring in soils, not all of it is
readily available to the plant - that
is to say, in a soluble form.
In fact, in most soils, somewhere
between 90 and 98% of the
naturally occurring potassium
is unavailable to the plant. For
example, while mineral soils rich in
feldspar and mica technically sport
high potassium content, plants
can't access this crystalline form.
Other soil processes will eventually
break down these mineral forms
into plant-accessible potassium,
but it's slow - happening over
tens of years and unable to meet
the season-long demands of a
growing crop.
What's more, a number of additional
factors also influence a crop's ability
to absorb potassium. Chief among
plant that potassium has an effect:
high levels also improve shelf life,
by boosting the fruit's resistance
to damage from handling and
transport.
these is soil moisture. Potassium
availability is linked to increased soil
moisture, as this makes potassium
more mobile. Research has
confirmed that crops display more
response to potassium fertilization
during a dry year.
As well as soil moisture, soil
aeration is also key - but here a
happy balance needs to be struck.
Roots need air for respiration, but
as soil moisture increases then soil
aeration decreases. In completely
saturated soils, oxygen levels will
be very low - with the decrease
in root respiration also depressing
potassium uptake.
Unsurprisingly, temperature is
also a key factor. Optimum soil
temperature for potassium uptake
is between 60-80°F.
While not directly relevant to
fruit crops, it's also known that
the tillage system can influence
potassium uptake, with min-till
systems seeing reductions in soil
potassium availability. Although
fruit growers can do little to change
this, it's interesting to note that
results of research to identify
possible causes for this point to
restrictions in root growth. Growers
may consider this as a factor in
well-established, multi-season
crops where soil is not regularly
disturbed - these could be crops
that are in need of some potassium
assistance.
Potassium deficiency, if it's spotted,
usually manifests itself in older
leaves first: they'll appear light
green and yellow, before turning
to leaf scorch. At later stages in the
season, small or misshapen fruit
may be an indication too.
It's in these sorts of circumstances
where growers might turn to a
foliar potassium fertilizer. Foliar
products offer a faster uptake than
soil-applied products; not only
does this give growers the chance
to correct any deficiency more
quickly, but it also improves use
efficiency - the plant can access a
greater proportion of what's been
applied.
OMEX®
CELL POWER® K25 has
been developed to offer growers
not just soluble potassium, but
also an important supplement of
the plant hormone cytokinin. Vital
for good root systems, its addition
in K25 helps to manage and
eliminate the plant stress that can
occur as fruit load develops later in
the season.
Using K25 from late bloom and
early fruit set allows growers to
produce quality produce from first
set all the way through to the final
set.
Learn more at www.OMEXusa.com.
The product names and brands
referenced here are registered and
trademarks of OMEX®
© OMEX® Agrifluids, Inc. 2021.
Agrifluids, Inc.
Call 559-661-6138
Visit www.OMEXusa.com
Email omexusa@omex.com
http://www.OMEXusa.com http://www.OMEXusa.com
June 2021

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