Potassium Deficiency in Potato
· Potato · Sweet Potato
Symptoms are mainly visible on older leaves and start to develop on young leaves only in case of severe deficiencies. Mild potassium deficiencies are characterized by the development of tip burn and later interveinal chlorosis on the leaf blade. In severe cases, these patches turn into a dry, leathery tan or dark brown scorch (necrosis) that usually progresses from the leaf edge to the midrib. The main veins remain green. Leaves tend to curl and crinkle and often collapse prematurely. Tubers show black spots at the stolon end and, when cut, they blacken rapidly. Potassium-deficient plants grow stunted and are more susceptible to diseases and other stresses such as drought and frost. Overall, this results in yield losses and affects the quality of the tubers.
Deficiencies may occur because of low reserves of potassium in the soil or limited availability to the plant. Soils with low pH can be problematic. Heavy irrigation and high rainfall wash the nutrients from the root zone and can lead to deficiency. Drought conditions, in turn, block the transport of water and nutrients to the plants. Sandy or light soils with little organic content are prone to nutrient leaching and drought, and may therefore cause problems. Potassium plays a essential role in the transport of water, the firmness of tissues and the exchange of gases with the atmosphere. In contrast to nitrogen deficiency, the symptoms in potassium deficiency are irreversible, even if potassium is applied to the plants.
Add organic matter in the form of animal manure or plant mulch to the soil at least once a year. Wood ash also has high potassium content. Liming acidic soils can increase potassium retention in some soils by reducing leaching.
A variety of potassium fertilizers is available in the market. The formulation of the potassium applied can play an important role in quality and yield of potato tubers. The most widely used product is potassium chloride. Other mineral fertilizers include potassium nitrate, potassium sulfate, and mono-potassium phosphate.