**10. Potassium increases crops quality**

K is usually the most abundant cation in the cultures, being found in the tissues in greater proportion in the ionic form (K+ ). K stimulates vegetation and tillering (grasses); increases the content of carbohydrates, oils, fats, and proteins; stimulates the filling of the grains, reducing the chopping; promotes storage of sugar and starch; helps symbiotic N fixation; increases the use of water; and increases resistance to droughts, frosts, pests, and diseases. As K improves the quality of agricultural products, it is described as the "quality nutrient." It is interesting to note the high correlation of K and proteins in the seeds of several cultivated plants, since cultures with high protein contents require (and export) large amounts of K through the grains.

Among the essential mineral nutrients for plants, K stands out for its influence in quality attributes that affect the concentration of phytonutrients critical for human health. However, many plants, nutritious solutions, and environmental factors often limit the absorption of K from the nutritious solution in sufficient quantity to optimize the quality attributes mentioned earlier [52].

**Author details**

Alfenas, Brazil

**References**

cabal: FUNEP; 1995. 43pp

UFLA; 1996. 50pp

(Bulletin, 347)

Paragominas, Brazil

Douglas José Marques<sup>1</sup>

Wellington Ferrari da Silva4

\*, Hudson Carvalho Bianchini1

1 Setor de Olericultura e Experimentação, Universidade José do Rosário Vellano,

2 Núcleo de Pesquisa Vegetal Básica e Aplicada, Universidade Federal Rural da Amazônia,

[1] Moraes CAG, Furlani PR. Cultivation of fruit vegetables in hydroponics in protected

[2] Castellane PD, de Araujo JAC. Nutritious Solution Cultivation—Hydroponics. Jaboti-

[3] Faquin V, Furtini Neto AE, Vilela LAA. Production of Lettuce in Hydroponics. Lavras:

[4] Haag HP, Monteiro FA, Wakakuri PY. Guava fruit (*Psidium guayava* L.): Development

[5] Martinez V, Cerda A. Influence of N source on rate of Cl, N, Na, and K uptake by cucumber seedlings grown in saline conditions. Journal of Plant Nutrition. 1989;**12**:971-983

[6] Cometti NN, Furlani PR, Ruiz HA, Fernandes Filho EI. Nutrition solutions: Formulation and applications. In: Manlio SF, editor. Mineral Plant Nutrition. Vol. 89. Viçosa: Socie-

[7] Goto R, Tivelli SW. Production of Vegetables in Protected Environment: Subtropical

[8] Furlani PR, Silveira LCP, Bolonhezi D, Faquim V. Hydroponic Plant Cultivation. Cam-

[9] Hoagland DR, Arnon DL. The Water Culture Methods for Growing Plants without Nutritious Solution. Berkeley: California Agriculture Experiment Station; 1950. 32pp

4 Departamento de Engenharia Nuclear, Programa de Pós-Graduação em Ciências e Técnicas Nucleares, Universidade Federal de Minas Gerais—UFMG, Belo Horizonte, Brazil

environment. Informe agropecuário, Belo Horizonte: MG; 1999. 113pp

and extraction of nutrients. Scientia Agricola. 1993;**50**(3):413-418

Conditions. São Paulo: Fundação Editora da UNESP; 1998. 319pp

dade Brasileira de Ciência do Solo; 2006. 11pp

pinas: IAC; 1999. 52pp. (Boletim técnico, 180)

\*Address all correspondence to: douglasjmarques81@yahoo.com.br

3 Instituto Federal de Muzambinho, Muzambinho, Brazil

, Allan Klynger da Silva Lobato2,3 and

http://dx.doi.org/10.5772/intechopen.72854

65

Potassium Fertilization in the Production of Vegetables and Fruits

K is a nutrient particularly required by carbohydrate-producing plants, as it participates in the photosynthetic process, transports carbohydrates from the leaves to the tuber or stalk, and activates the starch synthetase enzyme. In sugarcane, research results have shown a close relationship between the K content in the stems and with the sugar production. In the soybean culture, increased potassium fertilization promotes an increase in the grain protein content and a reduction in the oil content. This one fact can be understood by the participation of K in the process of protein synthesis in the plants. For citrus cultivation, it was observed that the increase of the K content in the leaves increases the size, the production, and the number of fruits. It also increases the vitamin C content and the percentage of acid in the juice, and decreases the concentration of soluble solids and the percentage of juice and solids/acid in the fruit.

The acidity in the tomato and the solids and starch content in the potato are positively correlated with the potassium fertilization, which also affects the composition and quality of strawberry, grape, grapefruit, pistachio, watermelon, and tomato. Generally, K appears to affect acidity, the pH, and carotenoid content. In tomato, the increase of K in the nutritive solution improves the color of the pulp and increases the content of lycopene, which is the carotenoid responsible for the red color of tomato and watermelon [53].

Lycopene is not essential for humans and animals, but research shows that it is then beneficial because it has antioxidant properties, which neutralizes free radicals that can cause cell damage. Lycopene is the most sensitive pigment to K deficiency, since K being an essential cofactor for protein synthesis, its deficiency could lead to reduced rates of enzymatic reactions involved in the synthesis of carotenoids and their precursors [54].
