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Current page is 2.3.3: Plant Food & Deficiencies
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PLANT FOOD NPK
(N) NITROGEN
Nitrogen is essential for plant growth. Nitrogen is a part of every living cell. The two forms of nitrogen which plants take up are in the ammonia (NH4) and nitrate (N03) ion forms. Most agronomic crops take up most of their nitrogen in the nitrate ion form. Plants will utilize N in the (NH4) ion form if present and available to the plant. Lack of nitrogen and chlorophyll means that plants cannot utilize sunlight as an energy source to carry on essential functions such as nutrient uptake. Research has proven foliar or leaf applications of nitrogen is one form of application that can supplement a plants nitrogen requirements during the growing cycle.
- Nitrogen is necessary for chlorophyll synthesis and as a part of the chlorophyll molecule is involved in photosynthesis.
- Nitrogen is also a component of amino acids.
- Nitrogen is needed for growth of plants.
From the Greek words "nitron genes" meaning "nitre" and "forming" and the Latin word "nitrum". Discovered in Scotland by Daniel Rutherford in 1772.
(P) PHOSPHORUS
Phosphate is a very important plant nutrient (macro-nutrient) needed for the plant to complete its normal production cycle. The highest level of P in young plants is found in tissue at the growing stage. As plants mature most of the P moves into the flower and then to the seed or fruit.
- Phosphorus is needed for photosynthesis.
- Phosphorus is necessary for plant respiration.
- Phosphorus is essential for energy storage and transfer.
- Phosphorus is needed for cell division.
- Phosphorus is necessary for cell enlargement.
- Phosphorus is essential for several other plant processes.
From the Greek word "phosphoros" meaning "bringer of light" (an ancient name for the planet Venus?). Discovered in Germany by Hennig Brand in 1669.
(K) POTASSIUM
An important function of Potassium is it's influence in efficient water use. It helps in the process of opening and closing of plant leaf pores, called the stomata. Potassium is found in cell walls which surround stomata. Adequate amounts of Potassium can increase stress conditions on plants during drought conditions. Potassium is also responsible for producing quality crops.
- Potassium is essential for protein synthesis.
- Potassium is important in the breakdown of carbohydrates, providing energy for plants.
- Potassium helps to control ionic balance.
- Potassium is important in the translocation of minerals.
- Potassium helps plants to overcome effects of disease.
- Potassium is essential in the fruit formation stage.
- Potassium helps improve shelf life of fruits and vegetables.
- Potassium is involved in the activation of more than 60 enzymes which regulate the rates of major plant growth reactions.
From the English word "potash" and the Arabic word "qali" meaning alkali ("K" comes from the Latin word "kalium"). Discovered in England by Sir Humphrey Davy in 1807.
IDENTIFY AND TREAT DEFICIENCIES
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Under nitrogen deficiency, the older mature leaves gradually change from their normal characteristic green appearance to a much paler green. As the deficiency progresses these older leaves become uniformly yellow (chlorotic). Leaves approach a yellowish white color under extreme deficiency. The young leaves at the top of the plant maintain a green but paler color and tend to become smaller in size. |
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As a rule, phosphorus deficiency symptoms are not very distinct and thus difficult to identify. A major visual symptom is that the plants are dwarfed or stunted. Phosphorus deficient plants develop very slowly in relation to other plants growing under similar environmental conditions but without phosphorus deficiency. Some species such as tomato, lettuce, corn and the brassicas develop a distinct purpling of the stem, petiole and the under sides of the leaves. |
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The onset of potassium deficiency is generally characterized by a marginal chlorosis progressing into a dry leathery tan scorch on recently matured leaves. This is followed by increasing interveinal scorching and/or necrosis progressing from the leaf edge to the midrib as the stress increases. As the deficiency progresses, most of the interveinal area becomes necrotic, the veins remain green and the leaves tend to curl and crinkle. |
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The very low mobility of calcium is a major factor determining the expression of calcium deficiency symptoms in plants. Classic symptoms of calcium deficiency include blossom-end rot of tomato (burning of the end part of tomato fruits), tip burn of lettuce, blackheart of celery and as leaf curl & yellow tip burn in many plants. |
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In its advanced form, magnesium deficiency may superficially resemble potassium deficiency. In the case of magnesium deficiency the symptoms generally start with mottled chlorotic areas developing in the interveinal tissue. The interveinal laminae tissue tends to expand proportionately more than the other leaf tissues, producing a raised puckered surface, with the top of the puckers progressively going from chlorotic to necrotic tissue. |
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The visual symptoms of sulfur deficiency are very similar to the chlorosis found in nitrogen deficiency. However, in sulfur deficiency the yellowing is much more uniform over the entire plant including young leaves. |
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In plants with poor boron mobility, boron deficiency results in necrosis of meristematic tissues in the growing region, leading to loss of apical dominance and the development of a rosette condition. These deficiency symptoms are similar to those caused by calcium deficiency. In plants in which boron is readily transported in the phloem, the deficiency symptoms localize in the mature tissues, similar to those of nitrogen and potassium. |
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Copper deficient leaves are curled, and their petioles bend downward. Copper deficiency may be expressed as a light overall chlorosis along with the permanent loss of turgor in the young leaves. Recently matured leaves show netted, green veining with areas bleaching to a whitish gray. |
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Chlorine is very abundant in soils, and reaches high concentrations in saline areas, but it can be deficient in highly leached inland areas. The most common symptoms of chlorine deficiency are chlorosis and wilting of the young leaves. The chlorosis occurs on smooth flat depressions in the interveinal area of the leaf blade. |
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An early symptom for molybdenum deficiency is a general overall chlorosis, similar to the symptom for nitrogen deficiency but generally without the reddish coloration on the undersides of the leaves. This results from the requirement for molybdenum in the reduction of nitrate, which needs to be reduced prior to its assimilation by the plant. |
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The early stages of the chlorosis induced by manganese deficiency are somewhat similar to iron deficiency. They begin with a light chlorosis of the young leaves and netted veins of the mature leaves especially when they are viewed through transmitted light. As the stress increases, the leaves take on a gray metallic sheen and develop dark freckled and necrotic areas along the veins. |
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The most common symptom for iron deficiency starts out as an interveinal chlorosis of the youngest leaves, evolves into an overall chlorosis, and ends as a totally bleached leaf. The bleached areas often develop necrotic spots. Up until the time the leaves become almost completely white they will recover upon application of iron. |
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It's hard to determine if plants have a deficiency of silicon, but regular doses of a Silicate Solution can provide a wide range of benefits. Silicate helps strengthen plant tissue helping plants flourish in adverse environmental conditions such as heat, drought, and frost. |
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In the early stages of zinc deficiency the younger leaves become yellow and pitting develops in the interveinal upper surfaces of the mature leaves. As the deficiency progress these symptoms develop into an intense interveinal necrosis but the main veins remain green |
