Essential plant nutrients and their functions

NITROGEN

Nitrogen is received by plants as nitrate or ammonium ions. It is utilized by plants to synthesize amino acids, which is the building blocks of proteins. The protoplasm of all living cells contains protein. Nitrogen is also required by plants for other vital compounds, namely chlorophyll, nucleic acids, and enzymes. Chlorosis is usually more pronounced in older tissue. Since nitrogen is highly mobile within plants, it tends to move from older to younger tissue when in short supply.

Symptoms of Nitrogen deficiency in plant

• Slow growth; stunted plants.
• Yellow-green color (chlorosis).
• Death of tips and margins of leaves, beginning with more mature leaves.

PHOSPHORUS

Phosphorus is received by plants as ortho-phosphate. Phosphorus is

present in all living cells. It is utilized by the plant to produce 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 helps in the stimulation of seedling development and root formation. It facilitate maturity and enhances 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.

Symptoms of Phosphorus deficiency in plant

• Slow growth; stunted plants.
• Purplish coloration on foliage of some plants (older leaves first).
• Dark green coloration.
• Delayed maturity.
• Poor fruit or seed development.

POTASSIUM

Potassium is received by plants in the form of potassium ions. It stays in

ionic form within cells and tissues. Potassium is important for translocation of sugars and for production of starch. It is needed in the opening and closing of stomata by guard cells. Potassium enhances larger root growth, more uniformly distributed xylem vessels throughout the root system and increases plant resistance to disease. Potassium increases the size and quality of fruits, nuts, and vegetables and improves winter hardiness of perennials. Plants which produce large amounts of carbohydrates have a high potassium requirement.

Symptoms of Potassium deficiency in plant

• Slow growth.
• Tip and marginal chlorosis.
• Weak stems and stalks.
• Small fruit or shriveled seeds.

CALCIUM

Calcium is received by plants as calcium ion. A structural nutrient, it is an important part in cell walls and membranes and is needed for the production 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 cannot be remobilized. Therefore, young tissue is affected first under conditions of deficiency. Since Calcium is not mobile, the requirements of a crop for Calcium after early fruit set are commonly supplied in the form of nutritional sprays.

Symptoms of Calcium deficiency in plant

• 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, discolored areas on fruits – blossom-end rot of tomatoes, peppers and melons; bitter pit or cork spot of apples and pears.

MAGNESIUM

Plant uptake of magnesium is in the form of the magnesium ion. The chlorophyll molecule, which is important for photosynthesis, contains magnesium. Magnesium serves as an activator of many plant enzymes required in growth processes. Magnesium is mobile in plants and can be readily translocated from older to younger tissue when it is deficient. Plants need magnesium to balance the generally high use of potassium from fertilizers and manure.

Symptoms of Magnesium deficiency in plant

• Interveinal chlorosis in older leaves
• Curling of leaves upward along margins.
• Marginal yellowing, with green “Christmas tree” area along mid-rib of leaf.

SULPHUR

Sulphur is utilized in the form of sulfate ions. Sulphur may also be taken in as sulphur dioxide from the air through leaves in areas where the atmosphere has been enriched with sulphur compounds. It is not readily available from wet table 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.

Symptoms of Sulphur deficiency in plant

• Retarded growth rate and delayed maturity.
• Young leaves light green to yellowish color. In some plants, older tissue may be
• affected also.
• Small and spindly plants.

MICRONUTRIENTS

ZINC

Zinc is received by plants as zinc ion and is an essential constituent of several important enzyme systems in plants. It controls the synthesis of indoleacetic acid which is an important plant growth regulator. Terminal growth areas are affected first when zinc is deficient. Deficiency is most prominent on soils with neutral or alkaline pH that are sandy or have low organic matter content including cut areas and are very high in presence of phosphorus.

Symptoms of Zinc deficiency in plant

• Decrease in stem length and rosetteing of terminal leaves.
• Reduced fruit bud formation.
• Mottled young leaves.

IRON

Iron is received by plants as ferrous ions and is required for the formation of chlorophyll in plant cells. It stands 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 prevailing in high pH soils, in situations with poor occurrence aeration, or when high levels of zinc or manganese are present.

Symptoms of Iron deficiency in plant

• Interveinal chlorosis of young leaves. Veins remain green except in severe cases.
• Twig dieback.
• In severe cases, death of entire limbs or plants.

MANGANESE

Manganese uptake is in the form of ion. Manganese stands 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 needed with zinc in foliar spraying of commercial citrus. Other tree crops may show deficiencies.

Symptoms of Manganese deficiency in plant

• Interveinal chlorosis of young leaves.
• Gradation of pale-green leaf coloration, with darker color next to veins. No sharp color distinction between veins and interveinal areas as with iron deficiency.

COPPER

Plant uptake of copper is in ionic form. Copper serves as an activator of numerous plant enzymes and it also play a role in the development of plant pigments that influence colour. Copper deficiency has been observed on trees and vines growing on organic soils and sands.

Symptoms of Copper deficiency in plant

• Stunted growth.
• Dieback of terminal shoots in trees.
• Poor pigmentation.
• Wilting and eventual death of leaf tips.
• Formation of gum pockets around central pith in oranges.

BORON

Boron is predominately in solution as boric acid, and is taken up by plants in this form. It functions in the differentiation of meristematic cells. Boron is involved in the regulation of metabolism of carbohydrates in plants. Almost 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. When boron is deficient, cells may continue to divide, but structural components are not differentiated.

Symptoms of Boron deficiency in plant

• 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

Molybdenum is received by plants as the molybdate ion. It is needed by plants for the utilization of nitrogen. Nitrate nitrogen is changed to amino acids by the nitrate reductase enzyme, this enzyme needs molybdenum. Molybdenum is required for the symbiotic fixation of nitrogen by legumes.

Symptoms of Molybdenum deficiency in plant

• Stunting and lack of vigor. This is similar to nitrogen deficiency, because of the
• key role of molybdenum in nitrogen utilization.
• Marginal scorching and cupping or rolling of leaves.
• Whiptail of cauliflower.
• Yellow spotting of citrus.