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