Potassium (K) deficiency symptoms

Potassium (K) deficiency symptoms:

Importance of the nutrient : 

1.     Potash is one of the important nutrients in determining the size of leaf (i.e, reduction in total leaf area) and the number of leaves at any given time of the plant growth period.

2.    Contrary to the poular belief, Banana plant requires Potassium in all its stages of development stages. There is intensive uptake of Potash by the plant at establishment stages also. See the percentage of 'K' requirement by the plant in all stages of development: 

 

3.    Effect of Potash on Banana yield is substantial as under:

Potassium improves:

• Number of hands per bunch.
• Number of fingers per hand.
• Length of fruit.
• Girth of fruit.
• Weight of fruit.
• Weight of bunch.
• Total sugar content in the fruit.
• Potassium enhances the transfer of mineral nutrients Nitrogen, Phosphorous, Calcium, Magnesium, Copper and Zinc in xylum. 

 

 Potassium deficiency symptoms in Banana plant:

a.  Older leaves exhibit orange-yellow chlorosis with brown patches and subsequent death.

 

Orange-yellow chlorosis of leaves

b.   Chocking of the leaves is also observed which results in delayed flower initiation followed by reduced fruit size due to poor filling. 

 Potassium deficiency symptoms and stage by stage impact on the Banana plant from 'MILD' stage to 'LETHAL' stage are given her under:

 1.    Old leaves of Banana turning to Yellowish orange in colour is the symptom of Potassium deficiency in very early stages (Stage 1). 

'K' deficiency - Stage 1 - Leaves turning to yellow orange.

2.    In Stage 2 of K deficiency impacting the banana leaf, necrosis starts at leaf margins. This is a moderate stage and it is the right time to initiate remedial measures by applying 'K'.   
  

'K' deficiency - Stage 2 -Necrosis starts at leaf margins.

 3.    In Stage 3 of K deficiency the necrosis which starts at leaf edges (in Stage 2) will become thick and long stripes and reach leaf midrib.

 

'K' deficiency - Stage 3 -Necrotic stripes reach leaf  mid rib.

4.    In Stage 4 of Potassium deficiency, most of the leaf desiccates and the typical curling of leaf starts.  It is the extreme condition and there will be a telling impact on the yield. 
 

'K' deficiency - Stage 4 -Leaf desiccates and curling of  leaf starts.

 5.    In Stage 5, which is lethal stage of Potassium deficiency, necrosis of leaf is complete and there is this characteristic symptom of bending of leaf with the leaf tip pointing towards base of the plant as pictured in Sl.No.6 here under.

6.  Final characteristic symptom of K deficiency:  Affected plants exhibit curving of the midrib and tip of the leaves point towards base of the plant.

Tip of the leaf points towards base of the plant

Control:

Apply through drip fertigation grade Sulphate of Potash ( 0:0:50 ) @ 5 kg/1000 plants every 4th day from 1st month till 10th month. OR Manual application of Muriate of Potash @ 60 g/plant every fourth day from 1st month up to 10th month.


Spray Potassium nitrate ( 13:0:46 ) @ 3g/lt of water on foliage and bunches every week till plant recovers from the symptoms.

Harmful effect of Banana cultivated in Sodic Soils:

In Sodic soils the large presence of Sodium element interferes with 'Potassium' uptake of the plant. Liberal use of Gypsum is recommended to offset the negative impact of 'Na' (Sodium) ion. 

Harmful effects of excess application of Potassium for Banana plant:

High Potassium levels in the soils will leas to:  

• Calcium deficiency.
• Magnesium deficiency.
• Symptoms of 'Blueing'.
• Create an imbalance of Magnesium / Potassium ration in the soil. 

For more details on correct application of Potassium in various stages of growth period of the plant visit the following links:

•  Fertlizer Target Chart. 

                              and  

• Fertigation schedule.

Regards,

A.Vishnu Sankar.

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