**1. Introduction**

Light, water, and nutrients are the three essential elements for plant growth and reproduction. The nutritional factor is concerned with the content, as well as understanding the important differences between the agricultural systems and managing the plants to provide nutrients. Water-soluble inorganic chemicals are absorbed by plant roots, and these are essential plant nutrients. Plant nutrients are taken up by the plant through many biological transformations that determine when and how plants will take them.

Approximately 17 chemical elements play an important role in plant growth. Carbon, oxygen, and hydrogen are derived from air and water. They form the dry part of the plant. They are obtained by photosynthesis and are not considered "nutrient" elements. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), chlorine (Cl), and nickel (Ni) elements

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

are obtained from the soil or hydroponic nutrient solution. Nutrient elements are essential for all plants. For some plant species, sodium, silicon, and nickel are basic nutrients and provide positive contributions to their growth, although they are not necessary for other plant species. It is imperative that the cobalt element is used for nitrogen fixation by legumes. Additional elements, such as selenium and iodine, are not necessary for plants but are necessary for humans and plant-consuming herbivores. Thus, it can be used as a nutrient for plants [1].

10–50 lbs/acre. **Micronutrient nutrients** (Fe, Mn, Zn, Cu, B, Mo, and Cl) are generally neces-

Potassium Nutrition in Plants and Its Interactions with Other Nutrients in Hydroponic Culture

http://dx.doi.org/10.5772/intechopen.71951

11

Potassium is found in a nutrient solution as almost completely free ion (K cation). Potassium ions or potassium cations play a role in **the cation exchange capacity (CEC)**. CEC prevents soluble cations from leaking out of the plant root. Potassium ions can swiftly exchange with

Most of the plant nutrients are ionic. The K cation is a place of importance in the hydroponic nutrient solution. In many stages of the plant's nutrient uptake and afterward, the potassium cation plays an important role. The additive provided by the potassium is either direct or indirect. Indirect effects also result from the cationic property of potassium. There are several parameters that provide these effects. These parameters can be expressed as **cation exchange capacity (CEC), pH value, electrical conductivity (EC), root temperature, total ionic concentration, osmotic pressure**. In the hydroponic nutrient solution, due to the presence of K cation, the amount of some ions is suppressed, while the amount of other ions is increased. In

The aim of this chapter is to emphasize the importance and role of potassium ion in the nutrient solution in the hydroponic system. The hydroponic system provides a controlled nutrient for the plant. Macronutrients and micronutrients required by the plant are given to the plant by controlled nutrient solution. Controlled nutrient supply increases the yield of the plant. The importance of potassium cations in transporting nutrient solutions to plants is great. Due to the cation exchange capacity, potassium ion affects many factors such as pH value, osmotic pressure and electrical conductivity in the nutrient solution given to the plant. These factors have an effective role in the productivity of the plant as well as in the nutrient uptake. The potassium ions enter the interaction and exchange process with other ionic nutrients through the cation exchange process in the hydroponic system. Therefore, this nutrient is an indispensable element of the hydroponic system. All these cases will be explained separately in

**2. Potassium nutrition in plants and its interactions with other** 

In hydroponic culture, nutrient solutions are the only source of plant nutrition. A solution containing all the plant nutrients must be applied in the correct balance. For the selection of fertilizers and preparation of hydroponic nutrient solutions, the following factors should be

**1.** Concentration of harmful elements such as sodium, chloride and boron, salinity and water

**2.1. Hydroponic nutrient solution commonly used for plant**

sary in quantities less than 1 lb/acre.

all these cases, there is a balance effect.

**nutrients in hydroponic culture**

quality should be considered.

other soluble ions [6].

the chapter.

considered:

Potassium, together with N and P, plays an important role in plant development. It is an important macronutrient for plants having many functions such as plant nutrition, activation of numerous enzymes, and protection of electrical potential gradients in cell membranes. It is also considered as an important cation that protects the anion-cation balance. Turgor regulation and osmotic regulation in plants are greatly controlled by potassium ion. In addition, potassium is responsible for balanced transport of water to the plant [2].

Potassium is often referred to as a quality element for plant production [3] and has proven to have a crucial role in many product quality parameters. Product quality parameters such as fruit size, appearance, color, soluble solids, acidity, vitamin content, taste, and shelf life are affected positively by supplying K in sufficient quantity. These properties are influenced by photosynthesis, translocation of photosynthesis, protein synthesis, regulation of stomata, activation of enzymes, and many other processes. The tolerance of potassium to environmental stresses, such as drought, excess water, wind, high and low temperature, and the role of potassium in plant water regulation are factors that increase the productivity of trees and the quality of fruits. Plants are extremely sensitive to diseases and pests. Optimum feeding of K comes from above these troubles. In addition, other effects of potassium can be listed as follows: high fruit juice content, high C vitamin content, acceleration of ripening of fruits, and resistance to physical degradation during transport and storage [4].

Potassium has two main functions in terms of water and nutrients in plants:


The relationship between the water and the nutrient content of the cell controls both the transfer of sugars produced by photosynthesis to the fruit storage organs and the transfer through the plant. The amount of potassium consumed in biophysical functions is higher than the amount spent in biochemical functions [5].

In order for plant growth to be healthy, all the essential nutrients are important at the same time. But there are huge differences in the quantities to be given to the plants. N, P, and K are **primary macronutrients** that should be given in amounts of about 50–150 lbs/acre. Ca, Mg, and S should be considered as **secondary macronutrients** required in quantities of about 10–50 lbs/acre. **Micronutrient nutrients** (Fe, Mn, Zn, Cu, B, Mo, and Cl) are generally necessary in quantities less than 1 lb/acre.

are obtained from the soil or hydroponic nutrient solution. Nutrient elements are essential for all plants. For some plant species, sodium, silicon, and nickel are basic nutrients and provide positive contributions to their growth, although they are not necessary for other plant species. It is imperative that the cobalt element is used for nitrogen fixation by legumes. Additional elements, such as selenium and iodine, are not necessary for plants but are necessary for humans

Potassium, together with N and P, plays an important role in plant development. It is an important macronutrient for plants having many functions such as plant nutrition, activation of numerous enzymes, and protection of electrical potential gradients in cell membranes. It is also considered as an important cation that protects the anion-cation balance. Turgor regulation and osmotic regulation in plants are greatly controlled by potassium ion. In addition,

Potassium is often referred to as a quality element for plant production [3] and has proven to have a crucial role in many product quality parameters. Product quality parameters such as fruit size, appearance, color, soluble solids, acidity, vitamin content, taste, and shelf life are affected positively by supplying K in sufficient quantity. These properties are influenced by photosynthesis, translocation of photosynthesis, protein synthesis, regulation of stomata, activation of enzymes, and many other processes. The tolerance of potassium to environmental stresses, such as drought, excess water, wind, high and low temperature, and the role of potassium in plant water regulation are factors that increase the productivity of trees and the quality of fruits. Plants are extremely sensitive to diseases and pests. Optimum feeding of K comes from above these troubles. In addition, other effects of potassium can be listed as follows: high fruit juice content, high C vitamin content, acceleration of ripening of fruits, and

**1.** It plays an important role in the activation of basic enzymes for the production of proteins

**2.** Potassium protects the water content in plants. Thus, as a biophysical function, it helps to maintain the turgor of the cells. Turgid cells protect the vitality of the leaf. Therefore,

The relationship between the water and the nutrient content of the cell controls both the transfer of sugars produced by photosynthesis to the fruit storage organs and the transfer through the plant. The amount of potassium consumed in biophysical functions is higher than the

In order for plant growth to be healthy, all the essential nutrients are important at the same time. But there are huge differences in the quantities to be given to the plants. N, P, and K are **primary macronutrients** that should be given in amounts of about 50–150 lbs/acre. Ca, Mg, and S should be considered as **secondary macronutrients** required in quantities of about

and plant-consuming herbivores. Thus, it can be used as a nutrient for plants [1].

10 Potassium - Improvement of Quality in Fruits and Vegetables Through Hydroponic Nutrient Management

potassium is responsible for balanced transport of water to the plant [2].

resistance to physical degradation during transport and storage [4].

photosynthesis proceeds efficiently.

amount spent in biochemical functions [5].

Potassium has two main functions in terms of water and nutrients in plants:

and sugars. For this biochemical function, K is required in small quantities.

Potassium is found in a nutrient solution as almost completely free ion (K cation). Potassium ions or potassium cations play a role in **the cation exchange capacity (CEC)**. CEC prevents soluble cations from leaking out of the plant root. Potassium ions can swiftly exchange with other soluble ions [6].

Most of the plant nutrients are ionic. The K cation is a place of importance in the hydroponic nutrient solution. In many stages of the plant's nutrient uptake and afterward, the potassium cation plays an important role. The additive provided by the potassium is either direct or indirect. Indirect effects also result from the cationic property of potassium. There are several parameters that provide these effects. These parameters can be expressed as **cation exchange capacity (CEC), pH value, electrical conductivity (EC), root temperature, total ionic concentration, osmotic pressure**. In the hydroponic nutrient solution, due to the presence of K cation, the amount of some ions is suppressed, while the amount of other ions is increased. In all these cases, there is a balance effect.

The aim of this chapter is to emphasize the importance and role of potassium ion in the nutrient solution in the hydroponic system. The hydroponic system provides a controlled nutrient for the plant. Macronutrients and micronutrients required by the plant are given to the plant by controlled nutrient solution. Controlled nutrient supply increases the yield of the plant. The importance of potassium cations in transporting nutrient solutions to plants is great. Due to the cation exchange capacity, potassium ion affects many factors such as pH value, osmotic pressure and electrical conductivity in the nutrient solution given to the plant. These factors have an effective role in the productivity of the plant as well as in the nutrient uptake. The potassium ions enter the interaction and exchange process with other ionic nutrients through the cation exchange process in the hydroponic system. Therefore, this nutrient is an indispensable element of the hydroponic system. All these cases will be explained separately in the chapter.
