ROLE OF POTASSIUM (K) IN APPLES
Potassium is a primary apple nutrient that plays a major role in achieving high quality fruit and maximum yields. Potassium is second most important nutrient after nitrogen needed by plants which is required for numerous plant growth processes. Apple trees absorb potassium in greater amount than any other nutrient. Apple trees require almost double levels of potassium than nitrogen. For higher yields and quality fruit potassium is needed in higher levels. Potassium does not make up any part of plant, so its role is to be considered indirect. Potassium activates different enzymes involved in plant growth. Insufficient potassium levels can cause abnormalities in plants like less color, stunned growth, poor fruit quality etc.
KEY ROLE OF POTASSIUM (K)
- It is required for plant growth and its overall development.
- It boosts fruit size and fruit color.
- It increases water use efficiency; making plant drought resistance.
- It helps in photosynthesis and food formation.
- It helps in transportation of nutrients, water and sugars in the plant.
- It helps in activating numerous enzyme systems.
- It makes plant cells thicker; making more difficult for pests to invade the plant. Hence makes the plant disease resistant.
- It is required for protein synthesis.
POTASSIUM (K) AVAILABILITY AND UPTAKE
Potassium is available in soil at higher levels but is relatively immobile in the soil. Most of the potassium in the soil is in the form of soil minerals which is not available to the plant.
Generally there are three forms of potassium available in soil.
- Unavailable Potassium
- Slowly available Potassium
- Readily available potassium
Unavailable Potassium is the mineral form of potassium which is in crystalline structure form. This type of potassium is not available to the plants; however, with time it breaks down and is available to the plant in very small levels.
Slowly available Potassium is the form, which is slowly available to the plants in the growing season. This form of potassium is found in the layers of clay minerals which get fixed in the soil. When there is enough moisture in clay, it releases potassium ions to the plants.
Readily available Potassium form gets dissolved in soil solution and is directly available to the plants. Plants have the greatest availability to absorb this form of potassium.
Potassium uptake depends on several factors
- Moisture in soil affects the uptake of potassium. Higher moisture content means greater availability of potassium to the plants.
- Soil needs enough air for the uptake of potassium. It is required to till the soil at regular intervals.
- Potassium uptake is more at high soil temperatures.
DEFICIENCY SYMPTOMS OF POTASSIUM
- Primary potassium deficiency symptom is burning of leaf margins.
- Lesser fruit size and color.
- Potassium deficient fruit is low in sugars.
WHEN AND HOW MUCH TO APPLY?
- Bud Burst stage,
- Fruit development stage, (30 days before harvest, If there is enough moisture in the soil)
- Post Harvest.
Annually, an average tree on seedling requires 700gms.-1000gms. of potassium (K).
- Muriate of Potash (M.O.P. 00-00-60) 60% K.
- Sulfate of Potash (S.O.P. 00-00-50) 50% K.
- Potassium Nitrate (13-00-45) 45% K.