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Role and Deficiency Symptoms
of Potassium in Tomato
Role and Deficiency Symptoms of Potassium in Tomato
Introduction
Potassium is used in carbohydrate metabolism and
increases water-use efficiency
It is essential for protein synthesis and activates enzymes
and controls their reaction rates
It promotes flower and fruit production and is vital for
maintaining growth and helping plants resist diseases
K management should be considered part of long-term
soil fertility management because K is not easily lost from
or added to the root zone
Role and Deficiency Symptoms of Potassium in Tomato
Role of Potassium in Plants
 Involved in osmoregulation and enzyme activation
 Regulates transpiration by stomata and transport of
assimilates
 Increases leaf area and chlorophyll content
 Delays leaf senescence and thus contributes to greater
canopy photosynthesis and crop growth
 Improves the plant’s tolerance of adverse climatic
conditions, lodging, insect pests, and diseases.
Role and Deficiency Symptoms of Potassium in Tomato
Sources of potassium
Chemical fertilizers
 Potassium chloride (Muriate of potash) (50% K)
 Potassium nitrate (37% K, 13% N )
 Potassium sulfate (40–43% K, 18% S)
Role and Deficiency Symptoms of Potassium in Tomato
K deficiency symptoms
 Woody stems and slow growth. Stems become weak
and fall down
 Leaves are blue-green in color and the interveinal
area often fade to a pale grey color
 Leaves may also have a bronzed appearance and
yellow and orange patches may develop on some of
the leaflets
 Fruits often ripen unevenly and sometimes have
green patches near the stalks
 Older leaves may look scorched around the edges
and/or wilted. Symptoms first appear on older leaves
Role and Deficiency Symptoms of Potassium in Tomato
Deficiency symptoms of K in leaves
Source: http://5e.plantphys.net/article.php?ch=t&id=289
Role and Deficiency Symptoms of Potassium in Tomato
Potassium deficient tomato fruit
Source:http://extension.umass.edu/vegetable/diseases/tomato-blotchy-ripening
Role and Deficiency Symptoms of Potassium in Tomato
Causes of K deficiency
 Lower K-supplying capacity of soil
 Low recovery efficiency of applied K fertilizers because of
high K-fixation capacity of soil or leaching losses
 Complete removal of previous crop straw/ residues
 Wide Na:K, Mg:K, or Ca:K ratios in soil and sodic/saline
conditions.
 Presence of excessive amounts of reduced substances in
poorly drained soils (e.g., H2S, organic acids, Fe2+) causing
retarded root growth and hence K uptake.
 Imbalanced fertilization especially excessive use of N or N and
P fertilizers with insufficient K application.
Role and Deficiency Symptoms of Potassium in Tomato
Let us sum up
 Potassium is used in starch and sugar synthesis so is more
important in vegetables and fruits
 Potassium is naturally found in wood ash
 Prevention and cure can be achieved in short term by
adding potassium-specific fertilizer called potash
 Adequate moisture is necessary for effective potassium
uptake; low soil water reduces K uptake by plant roots
 Limiting acidic soils also increase K retention in the soil by
reducing leaching