Potato Nutritional Requirements

Nutrient Functions

Nitrogen (N): Synthesis of proteins (growth and yield).

Phosphorus (P): Cellular division and formation of energetic structures.

Potassium (K): Transport of sugars, stomata control, cofactor of many enzymes, reduces susceptibility to plant diseases.

Calcium (Ca): A major building block in cell walls, and reduces susceptibility to diseases.

Sulfur (S): Synthesis of essential amino acids cystine and methionine.

Magnesium (Mg): Central part of chlorophyll molecule.

Iron (Fe): Chlorophyll synthesis.

Manganese (Mn): Necessary in the photosynthesis process.

Boron (B): Formation of cell wall. Germination and elongation of pollen tube. Participates in the metabolism and transport of sugars.

Zinc (Zn): Auxins synthesis.

Copper (Cu): Influences in the metabolism of nitrogen and carbohydrates.

Molybdenum (Mo): Component of nitrate-reductase and nitrogenase enzymes.

Nitrogen (N)

Adequate N management is one of the most important factors required to obtain high yields. Excessive soil N, applied late in the season delays maturity of the tubers and result in poor skin set, which harms the tuber quality and storage properties. Potatoes are a shallow-rooted crop, generally growing on sandy, well-drained soils. These soil conditions frequently make water and N management difficult since nitrate is susceptible to leaching losses. On these sandy soils, it is recommended that potatoes receive split applications of N during the growing season. This involves applying some of the total N requirement prior to planting and applying the remainder during the season with side-dress applications or through the irrigation system by Nutrigation (fertigation).

Phosphorus (P)

Phosphorus is important for early root and shoot development, providing energy for plant processes such as ion uptake and transport.?Roots absorb phosphate ions only when they are dissolved in the soil water. Phosphorus deficiencies can occur even in soils with abundant available P, if drought, low temperatures, or disease interfere with P diffusion to the root, through the soil solution. These deficiencies will result in stunt root development and inadequate function. At the tuber initiation stage, an adequate supply of phosphorus ensures that optimum number of tubers is formed. Following the tuber initiation, phosphorus is an essential component for starch synthesis, transport and storage.

Potassium (K)

Potato plants take up large quantities of potassium throughout the growing season. Potassium has an important role in the control of the plant water status and internal ionic concentration of the plant tissues, with a special focus on the stomatal functioning. Potassium?plays a major positive role in the process of nitrate reduction within the plant.

Potatoes require large amounts of soil K, since this nutrient is crucial to metabolic functions such as the movement of sugars from the leaves to the tubers and the transformation of sugar into potato starch. Potassium deficiencies reduce the yield, size, and quality of the potato crop. A lack of adequate soil K is also associated with low specific gravity in potatoes. Potassium deficiencies impair the crop’s resistance to diseases and its ability to tolerate stresses such as drought and frost. Applying K fertilizer with a broadcast application prior to planting is most commonly recommended.

Calcium (Ca)

Calcium is a key component of cell walls, helping to build a strong structure and ensuring cell stability. Calcium-enriched cell walls are more resistant to bacterial or fungal attack. Calcium also helps the plant adapt to stress by influencing the signal chain reaction when stress occurs. It also has a key role in regulating the active transport of potassium for stomatal opening.

Magnesium (Mg)

Magnesium has a central role in photosynthesis, as its atom is present in the centre of each chlorophyll molecule. It is also involved in various key steps of sugar and protein production as well as the transport of sugars in the form of sucrose from the leaves to the tubers. Yield increases of up to 10% were obtained in which regular application of magnesium fertilizers has been practiced.

?Sulphur (S)

Sulphur reduces the level of common and powdery scab. This effect is related to a reduction in the soil pH where sulphur is applied in its elemental form.

?Role of Nutrients by Potato Growth Stage

Nutrients play essential roles throughout the growth cycle of a crop.

Different stage Potato nutrient's Needs & Role

Planting

• Nitrogen and Potassium - early growth and dry matter?
• Phosphate - more tubers, growth and dry matter
• Sulfur - Protein production and nitrogen stabilization
• Potassium - enzimatic activity and growth

Post planting

• Nitrogen - split applications to reduce losses?
• Zinc and Manganese - Cell division and photosynthesis

Hilling

• Nitrogen - second split application?
• Calcium (+/- Boron) - cell division, good skin quality, internal rust spot reduction, stress tolerance – drought/heat.
• Phosphate - energy transfer and tuber set

Tuber initiation

• Phosphate- tuber set and energy transfer
• Zinc and Manganese – cell division and photosynthesis?
• Calcium (+/- Boron) – cell division, good skin quality, internal rust spot reduction, stress tolerance – drought/heat

?Bulking

• Nitrogen, Phosphate and Magnesium - maintain tuber growth?
• Calcium – improves skin finish and reduces disease, drought and heat stress impact