Nutrients and Their Functions
Nutrient/Function Identifying Deficiencies
Nitrogen (N) is taken up by plants as nitrate (NO3-) or ammonium (NH4+) ions. It is utilised by plants to synthesise amino acids, the building blocks of proteins. The protoplasm of all living cells contains protein. Nitrogen is also required by plants for other vital compounds, such as chlorophyll, nucleic acids, and enzymes. Chlorosis is usually more pronounced in older tissue. Since nitrogen is mobile within plants, it tends to move from older to younger tissue when in short supply. Slow growth; stunted plants
Yellow-green colour (chlorosis)
Death (necrosis) of tips and margins of leaves, beginning with more mature leaves
Phosphorus (P) is taken up by plants as ortho-phosphate PO43-. Phosphorus is present in all living cells. It is utilised by the plant to form nucleic acids (DNA and RNA). Through energy-rich linkages (ATP and ADP), it is involved in the storage and transfer of chemical energy used for growth and reproduction. Phosphorus stimulates seedling development and root formation. It hastens maturity and promotes seed production. Phosphorus supplementation is required most by plants under the following circumstances: (1) cold weather, (2) limited root growth period, and (3) rapid vegetative growth. Slow growth; stunted plants
Purplish colouration on foliage of some plants (older leaves first)
Dark green colouration
Delayed maturity
 Poor fruit or seed development
Potassium (K) is taken up by plants in the form of potassium ions (K+). It remains in ionic form within cells and tissues. Potassium is essential for translocation of sugars and for formation of starch. It is required in the opening and closing of stomata by guard cells. Potassium promotes root growth; produces larger, more uniformly distributed xylem vessels throughout the root system; and increases plant resistance to disease. Potassium increases size and quality of fruits, nuts and vegetables and improves winter hardiness of perennials. Plants that produce large amounts of carbohydrates have a high potassium requirement. Slow growth  
curling of leaves upward along margins
Weak stems and stalks
Small fruit and shriveled seeds
Calcium (Ca) is taken up by plants as the calcium ion (Ca2+). A structural nutrient, it is an essential part in cell walls and membranes and is required for the formation of new cells. For this reason, early season availability of supplemental Calcium has a distinct effect on fruit set. Once deposited in plant tissues, Calcium is not remobilised. Therefore, young tissue is affected first under conditions of deficiency. Since Calcium is not mobile, the requirements of a crop for Ca2+ after early fruit set are commonly supplied in the form of nutritional sprays. Tip burn of young leaves - celery, lettuce, cabbage
Death of growing points (terminal buds). Root tips also affected
Abnormal dark green appearance of foliage
Premature shedding of blossoms and buds
Weakened stems
Water-soaked, discoloured areas on fruits - blossom-end rot of tomatoes, peppers, and melons; bitter pit or cork spot of apples and pears.
Magnesium (Mg) is taken up by plants as the magnesium ion (Mg2+). The chlorophyll molecule, which is essential for photosynthesis, contains magnesium. Magnesium serves as an activator of many plant enzymes required in growth processes. Magnesium is mobile within plants and can be readily translocated from older to younger tissue with it is deficient. Plants need magnesium to balance the generally high use of potassium from fertilisers and manure.
Interveinal chlorosis in older leaves
Curling of leaves upward along margins
Marginal yellowing, with green “Christmas tree” area along mid-rib of leaf
Phalaenopsis ZadaSulphur (S) is utilised in the form of sulphate ions (SO4-). Sulphur may also be absorbed as sulphur dioxide (SO2) from the air through leaves in areas where the atmosphere has been enriched with sulphur compounds. It is not readily available from wettable sulphur which is in the form of elemental sulphur. Sulphur is a constituent of three amino acids (cystine, methionine and cysteine) and is therefore necessary for protein synthesis. It is essential for nodule formation on legume roots. Sulphur is present in oil compounds responsible for the characteristic odours of plants such as garlic and onion.
Phalaenopsis Zada
Retarded growth rate and delayed maturity
Young leaves light green to yellowish colour. In some plants, oder tissue may be affected also
Small and spindly plants
Zinc (Zn) is taken up by plants as the zinc ion (Zn2+) and is an essential constituent of several important enzyme systems in plants. It controls the synthesis of indoleacetic acid, an important plant growth regulator. Terminal growth areas are affected first when zinc is deficient. Deficiency is most common on soils with neutral or alkaline pH that are sandy or have low organic matter content (including cut areas) and are very high in available phosphorous. Decrease in stem length and rosetting of terminal leaves
Reduced fruit bud formation
Mottled young leaves (inaterveinal chlorosis)
Dieback of twigs after first year
Iron (Fe) is taken up by plants as ferrous ions (Fe2+) and is required for the formation of chlorophyll in plant cells. It serves as an activator for biochemical processes, such as respiration, photosynthesis, and symbiotic nitrogen fixation. Iron deficiency can be induced by high levels of manganese or high lime content in soils. Deficiencies are common in high pH soils, in situations with poor aeration, or when high levels of zinc or manganese are present.Phalaenopsis Zada
Interveinal chlorosis of young leaves. Veins remain green except in severe cases
Twig die back
In severe cases, death of entire limbs or plants
Manganese (Mn) uptake is in the form of the ion Mn2+. Manganese serves as an activator for enzymes in plant growth processes. It assists iron in chlorophyll formation. High concentrations of manganese in plants may induce iron deficiency. Manganese is generally required with zinc in foliar spraying of commercial citrus. Other tree crops may show deficiencies.
Interveinal chlorosis of young leaves.  
Gradation of pale-green leaf colouration, with darker colour next to veins. No sharp colour distinction between veins and interveinal areas as with iron deficiency.
Copper (Cu) is taken up by plants in the form of the copper ion (Cu2+). Copper serves as an activator of numerous plant enzymes and plays a role in the development of plant pigments that influence colour. A copper deficiency interferes with protein synthesis. Copper deficiency has been observed on trees and vines growing on organic soils and sands. Pleione formosanaPhalaenopsis ZadaPleione formosanaPhalaenopsis Zada Stunted growth
Die back of terminal shoots in trees
Poor pigmentation
Wilting and eventual death of leaf tips
Formation of gum pockets around central pith in oranges
Boron (B) is predominately in solution as boric acid, H3BO3, and is taken up by plants in this form. It functions in the differentiation of meristematic cells. Boron is also involved in regulating metabolism of carbohydrates in plants. Nearly all fruiting crops have a high demand for boron in the early fruiting stage. Foliar applications are an effective way to meet this demand at this critical growth state. Recent research has shown that boron is effective in increasing pollen viability, thus contributing to increased fruit set. When boron is deficient, cells continue to divide, but structural components are not differentiated.Phalaenopsis ZadaPleione formosanaPhalaenopsis Zada Death of terminal growth, causing lateral buds to develop, producing a “witch’s broom” effect
Thickened, curled, wilted and chlorotic leaves
Soft or necrotic spots in fruit or tubers
Reduced flowering or improper pollination
Molybdenum (Mo) is taken up by plants as the molybdate ion (MoO4-). It is required by plants for the utilisation of nitrogen. Nitrate nitrogen is converted to amino acids by the nitrate reductase enzyme; this enzyme requires molybdenum. In addition, molybdenum is required for the symbiotic fixation of nitrogen by legumes.Phalaenopsis ZadaPleione formosana Stunting and lack of vigour. This is similar to nitrogen deficiency, because of the key role of molybdenum in nitrogen utilisation.
Marginal scorching and cupping or rolling of leaves
Yellow spotting of citrus