Potassium in the plant for growth and yield
Potassium is an essential macronutrient. Many crops require this nutrient in large quantities. A plant is only able to absorb potassium from the soil when it is dissolved in solution (K+). Potassium is highly mobile within the plant and plays a major role in water management. Unlike most other nutrients, potassium is not converted into complex organic molecules within the plant (with the exception of wood), but instead functions as an important co-factor in numerous physiological processes.
Processes
- Regulation of water pressure (turgor) in plant cells, important for cell expansion, respiration (opening and closing of stomata), water uptake, and the orientation of leaves toward light;
- Activation of enzymes;
- Formation and transport of organic compounds within the plant, such as sugars, amino acids, and starch;
- pH regulation within plant cells;
- Fixation of carbon dioxide during the photosynthesis process;
- Balancing electrical charges in various parts of the plant cell;
- In addition, crops are better able to withstand stress and damage from insects and/or diseases when they can absorb sufficient potassium;
- Potassium requirements of the crop throughout the growing season.
High potassium demand
After nitrogen, potassium is the nutrient required in the largest quantity by plants. When insufficient potassium is available, growth is inhibited and the plant begins to mobilize potassium from older leaves. A serious potassium deficiency is first visible through chlorosis (yellow discoloration) in the lower parts of the plant, especially at the leaf tips and edges (tip burn). In addition, potassium deficiency weakens the lignification of vascular tissues, causing plants to lose strength and increasing the risk of lodging.
The crop’s demand for potassium increases significantly throughout the season. Potassium requirements are especially high during the flowering and fruit-setting stages. As a positively charged ion, potassium is highly important for the uptake and transport of negatively charged ions such as nitrate, phosphate, and amino acids. Potassium also regulates the translocation of sugars and starches from the leaves to storage organs such as fruits, bulbs, and tubers.
When a potassium deficiency occurs during this period, it directly affects the quality of the harvested products. In fruit vegetables, potatoes, and onions in particular, potassium plays a crucial role during the ripening and storage phases.
Optimal potassium fertilization
Mineral applications in the form of animal manure, compost, and/or mineral fertilizers replenish soil potassium reserves at the start of the season. However, potassium availability strongly depends on climatic conditions. Potassium can only be absorbed by the plant when sufficiently dissolved in soil moisture.
Excessively wet conditions can cause potassium to leach relatively easily (especially on sandy soils), while dry conditions reduce its availability. This is why applying additional potassium during the season through foliar fertilization can be highly beneficial. Particularly in potassium-demanding crops such as potatoes, sugar beet, and onions, foliar fertilization can offer major advantages.
Soiltech specifically developed the product Optima Leaf-K for these applications. It consists of organically complexed potassium. Unlike many other potassium foliar fertilizers, Optima Leaf-K has a relatively low EC (salt level), a neutral pH, and excellent compatibility with other products. In recent years, the product has repeatedly proven itself in field trials, including in onion cultivation.
More information? Click here: Optima Leaf-K
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