COMMON NUTRIENT DEFICIENCIES Next to carbon dioxide, water and oxygen, plants require nutrients for growth and development. These ‘nutrients’ or ‘minerals’ are chemical elements and are essential for all plants species. There are twelve nutrients, categorised into two groups: macro and microelements. This distinction is made on the basis of the quantity taken up by plants. Macroelements are nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg) and sulphur (S). The micro-elements are iron
species. Sodium (Na) and
The essentiality of a few
(Fe), manganese (Mn), zinc
chloride (Cl) will be found in
micro-elements as cobalt
(Zn), boron (B), copper (Cu)
plants as well, sometimes
(Co) and nickel (Ni) and
and molybdenum (Mo).
in huge quantities, however
some other rare elements
Sometimes silicon (Si) is
these elements do not
is still debated among
also mentioned as nutrient,
have an essential function
scientists. These elements
however this element is
and can be replaced by
may be essential for some
not an essential, but rather
others. These elements
species but not for all and
considered as ‘beneficial’
are taken up by plants
accordingly these elements
and is only taken up by a
due to their presence
are generally neglected.
selective number of plant
in the root environment.
Article written for Reiziger by
University & Research Center. The Netherlands.
Early recognition will help overcome problems.
114
Nutrient Deficiency. The quantity and the mutual
optimise growth by avoiding these
overcome the problem. In some
ratio of each of these nutrients
shortages by crop management,
cases this is too late and plants
required for optimum growth
in particular fertilisation.
will not recover or the symptoms
differs substantially among plant
In horticulture and specifically
have had already detrimental
species (see graph below). In
in soilless culture systems like
effects on the crop. Deficiency
nature, plants will be provided
hydroponics, an optimal nutrient
may occur due to an absolute
these nutrients by the soil. This
solution is provided to boost plant
lack of the specific nutrient in
natural soil fertility (among other
growth even more. However,
the soil or the substrate or due to
conditions) constrains the growth
if there is an unbalanced
conditions in the root environment
and the development of plants.
fertilisation, depletion of one of the
or the condition of the plant. For
Plant species have evolved
nutrients may occur and plants
instance a too high or too low pH
many strategies to overcome
will start to show symptoms.
will reduce the availability of some
shortages. Some plants have
These deficiency symptoms are
nutrients (Fe, Mn, Zn). Lack of
superior strategies than others
typical for each nutrient and may
oxygen or too low temperature will
and this is one of the pillars of
vary among plant species. Early
reduce the capability of roots to
the biodiversity we can observe
recognition of the symptoms and
take up nutrients as well.
in nature. In agriculture, we
adequate actions will help to Minerals 15%
Dry Matter 13%
TOTAL PLANT
DRY MATTER O
87%
Water
43%
5% H
37% C
Mo Cu 1% 7%
P Mg 5% % S 3 % Cl 2 % 2 % Na 1
Ca 21%
B 25%
MINERALS
Fe 29%
MICRO NUTRIENTS
% N 20
46% Mn
14% Zn
24% Mn
Essential Nutrients. Nutrients are essential for plant growth as they are part of the ‘building blocks’ of the plant or are indispensable for certain processes. The lack of nutrients will limit plant growth or influence the life cycle. For example N is the key element in amino-acids, the basic components of proteins. Proteins are one of the
Nutrient Toxicity.
important ‘building blocks’ of plant cells. So it
Plant roots are very selective
to problems with the water
in taking up the required
quality. Toxicity symptoms
quantities of nutrients from
have common features
the root environments. Even
but will have some typical
if the plant has absorbed
aspects for each plant
too much, the plant has
species as well. Toxicity of
mechanisms to reverse the
macro elements is virtually
uptake by excretion of the
unknown, although a too high
surplus of some nutrients.
supply of (one of the) macro-
However, in some cases
elements will cause problems
this selection is overruled
as well. These problems are
if the concentration of a
related to the interferences
certain nutrient is high. For
with other nutrients
some nutrients the plant
(antagonistic effects). In this
cannot control the uptake
case early recognition of the
and toxicity will occur. This
symptoms and adequate
is mainly the case with some
actions are important, but it is
of the micro-elements, like
not always easy to overcome
for B, Mn, Cu and Zn. Under
the problem. In some cases
horticultural and soilless
this may be too late and
culture conditions toxicity
plants will not recover, or the
is usually due to errors
symptoms have already had
made by the preparation
detrimental effects on
of fertiliser solution, an
the crop.
inadequate substrate, or due
is quite obvious that without N, plants are not able to grow at all.
Minerals magnified Various minerals important for growth seen closeup and in detail.
K however is never part of any molecule in the plant; it stays 100% in solution as the K+ ion. K controls a lot of functions inside the cell solutions. Another example of the second category nutrients is Cu, which is not part of any building block. Plants can grow to a certain extent without Cu. However, Cu is part of some enzymes that control metabolic processes in the plant, for instance it is necessary for the viability of pollen in grains, or the induction of flowers.
Individual nutrient deficiencies. The main functions, deficiency symptoms and prevention measures of the essential nutrients are described in more detail on the next pages. For each nutrient, the common features of deficiency symptoms and under which conditions it will occur as well as which measures can be taken to cure the problem are presented. If toxicity is known, this is described as well.
Deficiency symptoms and prevention measures of essential nutrients.
First aid guide for plants.
N Nitrogen Nitrogen is by far the most important nutrient. It is one of the components of amino acids and therefore an important part of the proteins, DNA, enzymes, vitamins and above all, the chlorophyll, which is the key for plants to function.
Stage 01
Stage 02
Stage 03
The plant is a lighter colour as a whole.
Stalks will turn purple and leaves will yellow.
Further yellowing and whitening occurs in top and middle sections.
Purple stalks
Yellowing
Leaf drop
Function
Deficiency
Prevention and cure
Nitrogen is absorbed in two forms: nitrate (NO3-) and ammonium (NH4+). NO3- absorbed by the root is transferred to NH4+ before it is processed into amino acids. For this process some enzymes are needed and molybdenum (Mo) is crucial. In the plant, nitrogen is very mobile and a lot of nitrogen from proteins and amino acids in older plant parts is recycled.
Nitrogen deficiency will be shown in the first place as growth reduction and soon the leaf colour becomes dull green or pale. Then the oldest leaves turn yellow and in a later stage will become brown and dye off. In the case of fruit crops, the fruit setting will be poor and fruits become small. Since nitrogen is very mobile in the plant, yellowing always starts in old leaves, whereas young leaves and the top of the plant stay green.
To prevent shortages, an adequate fertilisation by sufficient base dressing of soil and substrate and continuous fertigation is required. Soil or substrate (drainage) analysis will be excellent methods to indicate impending shortage. Plants will recover rapidly after restoring the nitrogen supply.
Deficiency occurs due to incorrect feeding or food contains insufficient nutrient elements. Substrates that contain a lot of fresh organic material can cause nitrogen deficiency because micro-organisms bind the nitrogen. Raise EC of the feeding.
Add extra nitrogen.
K Potassium K is the nutrient present in the highest quantities. In the plants it stays soluble as ion (K+) and is never part of the dry matter. The majority of K is present in the vacuole solution of cells, keeping the osmotic potential and controlling the water potential of plant tissue.
Stage 02
Stage 03
Tips of younger leaves show grey edges.
Leaves turn yellow from the edge and rust coloured dead spots.
Leaf tips curl up radically and sections of the leaf begin to rot.
Grey edges
Rust spots
Dead edges
Function
Deficiency
Prevention and cure
Stage 01
Potassium can be rapidly moved inside the plant and plant cells and therefore plays an important role in opening and closing of stomata, i.e. the regulation of the transpiration. Potassium is absorbed solely as K+.
Potassium deficiency starts with some growth reduction and darkening of the young leaves. Symptoms will become visible as necrosis of the leaf margins of the mature, older leaves of the plant and eventually the whole leaf becomes necrotic. In case of fruit crops, the fruit quality (shelf life, colour, taste) is negatively affected.
To prevent shortages, an adequate fertilisation by sufficient base dressing of soil and substrate and continuous fertigation is required. Soil or substrate (drainage) analysis will be excellent methods to indicate impending shortage. Plants will recover rapidly after restoring the potassium supply, except for the necrotic tissue.
Potassium is absorbed quickly and easily by the plant. In a hydroponic system results are visible within several days. Potassium supplementation via leaf fertilisation is not recommended. Rinse substrate with water.
Add extra potassium.
P Phosphorus Phosphorus is part of the amino acids and so a basic building block of proteins. In addition to DNA, ATP and ADP-proteins, which form the energy source for all metabolic processes in plant cells, are a typical destination for phosphorus.
Stage 01
Stage 02
Stage 03
Plant becomes a sort of dark blue-green.
Dark necrotic spots appear on old and medium aged leaves.
The purple-black necroses expand to the leaf’s stem.
Blue-green
Necrotic spots
Black stems
Function
Deficiency
Prevention and cure
Phosphorus is quite mobile in the plant and like nitrogen, the phosphorus from old plant tissue is recycled. For young plants, the presence of phosphate is indispensable; about three quarters of the phosphorus consumed during a plant’s life cycle is absorbed in the first quarter of its life. The largest concentrations of phosphorus are found in the developing parts of the plant: the roots, the growth shoots and the vascular tissue.
Typically a phosphorus deficiency is seen as growth reduction and very dark coloured green leaves at the top. This is often accompanied with a blue-green to purplish colouring, mainly on the underside of the leaf. The mature leaves become smaller and leaflets or tops of leaves will curl downwards. Purple colouring will also occur on the stem and petioles. Stunted growth and lacking to form a heart (lettuce) may also occur, as well as dying of the older leaves (pepper).
The availability of phosphorus in the root environment is complicated as phosphorus is absorbed to the soil and soil chemical properties (pH) influence the form in which phosphorus is available. For soilless culture and hydroponics, it is therefore absolutely necessary to control the pH and keep the pH between 6.2 and 5.0. If the pH is above 6, a drainage analysis is inadequate as P may be present in forms that are not available for plant uptake.
In case of a phosphorus deficiency, reduce the pH, for instance by 10-20% by adding extra NH4+. After additional phosphorus supply or optimisation of the pH conditions, plants will recover rapidly. Reduce the pH below 6.2.
Add extra phosphorus.
Ca Calcium Calcium is part of the cell wall and cell membranes and therefore indispensable for the elasticity and rigidity of the plant tissues. Ca is taken up as Ca2+ ion and is transported only by the xylem vessels and therefore very immobile in the plant.
Stage 02
Stage 03
Small, light brown spots that increase in size over time.
Spots now appear at the edge of the leaves.
Older leaves die off slowly and yellowish cloudy spots may appear.
Brown spots
Sharp rust spots
Hindered growth
Function
Deficiency
Prevention and cure
The water flow in the plant due to transpiration is the most important factor to provide the plant with calcium. Root pressure (the process caused by the differences of concentration inside and outside the plant) is another important factor as this will bring calcium into littletranspiring plant parts like fruits and plant tops.
Typically necrosis of young tissue, like young leaves, tops or fruits. The main reason is cell lesion due to weak cell walls in combination with permeable membranes. This young tissue is unable to sustain transpiration when exposed to the environment. Calcium deficiency symptoms are among the most common deficiencies in protected horticulture, even in well fertilised conditions.
Take care of adequate base dressing and fertigation, avoid high NH4, potassium and magnesium concentrations. However, this is not a guarantee for prevention of calcium deficiency. Prevent long periods of high humidity and at least prevent sudden shocks in the humidity conditions. For some crops, a foliar application of CaCl2 (0.1%) will help, but needs to be repeated frequently.
Stage 01
The main reason for deficiency is irregularities in water distribution caused by the climate conditions. In addition, high salinity and also high NH4+ concentrations are factors that may cause calcium deficiency. Rinse substrate with water.
Apply additional calcium.
Mg Magnesium Magnesium is part of the chlorophyll. Without magnesium, the chlorophyll is unable to be active. Furthermore, it is part of some enzymes. It is quite mobile in the plant when chlorophyll is degraded. Magnesium is recycled in the plant.
Stage 01
Stage 02
Stage 03
Small, rusty brown spots or cloudy yellow flecks appear.
The size and number of rust brown spots increase.
Symptoms spread out over the entire sick looking plant.
Small brown spots
Cloudy yellow spots
Plant looks sick
Function
Deficiency
Prevention and cure
It represents a building block for chlorophyll (leaf green) and it is essential for photosynthesis. At the same time, magnesium plays an important role in the energy transfer. Together with calcium, it is also a component of tap water, influencing water hardness. Inorganic magnesium fertilisers are produced using the same bases that are used to produce potassium fertilisers.
Magnesium deficiency causes yellowing of the leaves due to chlorophyll degradation. Plants will try to keep the youngest leaves green, so mature and middle aged leaves will show the deficiencies first. The yellowing is interveinal. In severe situations, the yellow parts become necrotic and leaves may eventually become completely brown. The fruit colour will be negatively affected.
Adequate fertilisation with a sufficient base dressing of soil and substrate plus continuous fertigation. Soil or substrate (drainage) analysis will be excellent methods to indicate impending shortage. Plants will recover rapidly after restoring the Mg supply, however the yellowing of the leaves will not disappear. Repetitive spraying with MgSO4 (max 0.5%) is an adequate cure.
When there is a shortage, the leaf green in the medium-aged leaves under the flowering top will be broken up and the magnesium will be transported into the younger leaves of the plant. Keep root temp at 20-25°C.
Avoid a high EC in the substrate.
Fe Iron Iron is a vital element for plant life. As iron can easily be transferred from Fe2+ to Fe3+, the function of iron ions in plants is to act as an electron donor or acceptor. These reactions occur in many metabolic processes, particularly in the chlorophyll.
Stage 02
Stage 03
Green-yellow chlorosis from inside to the outside.
Continued yellowing of the leaves to almost white.
Leaves show necrosis with growth and flowering inhibited.
Yellow chlorosis
Continued yellowing
Strong yellowing
Function
Deficiency
Prevention and cure
In general, iron is poorly absorbed by the plant. It can only be sufficiently taken up by the roots in certain forms and under proper conditions. Without iron, the assimilation process in chlorophyll cannot function. Iron can be absorbed as Fe2+ or Fe3+, but in normal conditions with abundant oxygen present this will usually be Fe3+. Iron is very immobile in the plant.
Iron deficiency can occur during periods of heavy growth or high plant stress and is easy to recognise as the youngest leaves of plants become yellow, leaving the veins usually green. This phenomenon is called chlorosis. The young leaves can’t draw any iron from the older leaves. After the initial yellowing, the leaves become necrotic after exposure to high radiation and later die off. In severe situations, plants will die completely.
Adequate fertilisation by sufficient base dressing of soil and substrate and continuous fertigation with the right Fe-chelate type is important. Fe-chelates are used (in the nutrient solution) to keep Fe in solution otherwise Fe will precipitate rapidly. The availability of Fe in the root environment is complicated, as the pH plays a major role. In hydroponics, it is absolutely essential to control the pH. Foliar spray of Fe-chelate with max 0.5% may help for prevention.
Stage 01
Keep pH between 6.2-5.0. Poor root development or unformed young root tips (due to soil compaction oxygen deficiency) can be a cause. In case of Fe-deficiency due to pH problems, reduce the pH by 10-20% with NH4+. Reduce the pH by 10-20%.
Foliar spray of Fe-chelate with max 0.5%.
Mn Manganese The metal manganese is an essential trace nutrient activating different enzyme reactions in the plant and plays an essential role in certain enzymes necessary for photosynthesis. Manganese is absorbed as Mn2+ but is quite immobile in the plant.
Stage 01
Stage 02
Stage 03
Yellow stripes between the leaf’s side veins on larger leaves.
Yellowing between the side veins spreads further over the leaf.
Yellowing spreads further. Yellowbrown necrotic spots can form.
Yellow stripes
Yellowing spreads
Necrotic spots
Function
Deficiency
Prevention and cure
Manganese acts as an activator for different enzyme reactions in the plant, for example in water-splitting during photosynthesis, the synthesis of amino acids and proteins and the build up of plant cell membranes and chloroplasts. Manganese is generally taken up via the roots. Once inside the plant it is difficult to transport but not as difficult as calcium or iron for example. Silicon and molybdenum improve the transport possibilities for manganese in the plant.
A manganese deficiency causes different physiological changes in the plant due to a decrease in protein production. The symptoms are quite similar to iron, although the youngest leaves may stay green and the symptoms will be visible in the larger top leaves. Compared to iron, the ‘netting’ pattern of the green veins is finer as smaller veins will be kept green, causing a greener touch to the whole leaf compared to an iron deficiency.
The availability of Mn in the root environment is largely dependent on the pH. For soilless culture and hydroponics, it is absolutely necessary to control the pH (keep pH between 6.2 and 5.0). In case of Mndeficiency due to pH problems, reduce the pH, for instance by 10–20% by adding extra NH4+. Foliar spray of MnSO4 or Mn-chelate (max 0.5%) may help for prevention. Cure of affected leaves is sometimes possible.
High concentrations of Mn precipitate into manganese oxide which cause yellow-brown spots on the leaves. Initially, small spots will appear along the main and side veins of the leaf, then the spots will spread out from the veins. Keep substrate temp at 20-25°C.
Lower substrate pH to 5.0-5.5.