The deficiency of nitrogen is manifested by yellowing of middle portion of the leaf blades while the margins remain green in monocot plants (grasses, Dracaena, lilies) and uniform yellowing of leaf blade in dicot plants (Hibiscus, Roses, Ficus). In both the groups the deficiency symptoms are first observed in older leaves. Since nitrogen deficient plants have less chlorophyll the manufacture of carbohydrates is impaired as a result of which there is poor growth and production.
The nitrogen deficiency should be corrected by replenishing with organic manures such as well rotten cow dung (cow manure) and by addition of fertilizers such ammonium sulphate, urea etc.
On the other hand, Excess of Nitrogen results in rapid vegetative growth, dark green leaves, soft and succulent growth, and delayed flowering.
Phosphorus has an important role in photosynthesis, respiration, cell division, and for sugar-starch transformation in plants. It functions as a part of the enzyme system which participates in many vital chemical reactions in plant body. Phosphorus is required for the formation of nuclear proteins. It is needed for early maturity, and for seed and fruit production.
Phosphorus deficiency causes stunted growth, late maturity, shrunken seeds, reddish or purplish veins and areas on leaves. The deficiency is corrected by addition of phosphoric fertilizers. Maintenance of correct soil pH which is generally between 5.5 to 6.8 is essential in phosphate management.
Potassium is actually not a constituent of any plant compound or tissues. However potassium plays a role in synthesis of Amino acids. Potassium is believed to give resistance to plants against diseases. Potassium deficiency causes weak stem, underdeveloped roots, and discoloration of leaves. The margins of leaves first show yellowing which gradually increases in size and turns brown. The older leaves show symptoms first.
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Sulphur is a necessary part of glycine molecule and for vitamin B. This is also needed in the formation of Chlorophyll. Sulphur deficient plants show thin and erect stems, and young leaves turn light green.
Calcium is an important constituent of cell wall. This element is responsible for the absorption of nitrate nitrogen. The typical symptom of deficiency is that the upper leaves become yellowish green while the lower leaves remain green.
Magnesium is a part of the center of molecule of both Chlorophyll a and b, and is also a constituent of the cell wall. Magnesium deficiency causes loss of chlorophyll and the symptom manifests on the leaves where the areas in between the veins become pale in color while the veins themselves remain green.
Deficiency of trace elements:
- As a result of deficiency of both manganese and iron, chlorophyll fails to develop.
- In boron deficiency, cell division slows down and plants fail to produce vegetative and flower buds.
- Zinc is necessary for cell elongation, cell elasticity. Zinc deficient branches have small, narrow, mottled leaves, and such branches generally die back.
- In copper deficiency, young leaves are permanently wilted; twig or stalk just below tip and seed head is often unable to stand erect in later stage when shortages are acute.
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Among the mineral nutrients, Nitrogen, Phosphorus and Potash (NPK) are required by plants in large quantities and hence these affect plant growth more compared to other mineral nutrients, micronutrients and trace elements.
For other symptoms, you may want to read more more about ‘What’s wrong with my houseplants?’