Potassium deficiency
Potassium (K)
K is an alkali metal with atomic number - 19 and atomic weight - 39.09. It is an essential macronutrient in plants. Plants absorb K in its ionic form (K+) from the soil water. It is considered as second most important nutrient after N and considered as quality nutrient. K is readily soluble in water and leaches from the soil with the water.
Function
In plants K is required throughout the life-cycle in order to perform several functions.
- K helps regulate the opening and closing of stomatal pores.
- K is involved in enzyme activation, which regulate the starch, protein and ATP (Adenosine TriPhosphate) synthesis in plants.
- K maintains ionic balance in the cytosol and vacuole.
- K regulate the water balance in plants by controlling the absorption of water through the roots and transpiration through the stomatal pores.
- K improves the drought resistance in plants.
- K regulates translocation of photosynthates (carbohydrates) through the phloem.
- K helps in cellulose synthesis and prevent lodging of plants.
Deficiency symptoms
K-deficient plants exhibit following symptoms.
- General plant growth including roots, stems, leaves, fruits and seeds are reduced.
- Characteristic symptoms of K deficiency in monocots is brown-scorching of leaves along the margins.
- In dicots yellowing occurs between the veins.
- As K is mobile in plants, in K-deficiency plant allocate K to younger leaves from the older leaves. Hence, yellowing of leaves starts from the lower(older) leaves.
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| Rice leaves showing browning at the tip and margin |
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