**5. Production of specialty vegetables through hydroponic nutrient management**

Potassium plays an important role in our body through several vital electrolytic activities. Chronic kidney disease (CKD) patients can't excrete unnecessary potassium through their impaired kidneys and thus get accumulated in the blood. This abnormally elevated level of potassium in the blood causing hyperkalemia disease to them. Hyperkalemic or dialysis patients are suggested to avoid potassium-rich food, but our daily diets including fruits and vegetables are rich in potassium. Therefore, production of low potassium content fruits and vegetables would benefit this type of people greatly.

In general, the greenhouse cultured raw melon has higher potassium content of 340 mg/100 g fresh weight [25]. Significant decreases in potassium content in melon fruits would improve the diet of dialysis patients. Therefore, quantitative management of hydroponic culture solution yielded melon fruits having sufficiently low potassium content (**Figure 1**) [16]. A simple management of

**Figure 1.** Reduced potassium nitrates levels decrease the fruit potassium content of netted melon grown in hydroponics [16].

culture solution was used for melon by reducing the potassium at lowest possible level. Therefore, melon plants were grown in nutrient solution with reduced KNO3 concentrations from anthesis till harvest to investigate its impact on the fruit potassium content while maintaining normal growth, yield, and other fruit qualities. On the other hand, sodium concentration in melon fruits followed the reverse trend of potassium concentration. Its concentration increased significantly in all the reduced potassium levels of KNO3 supplied during anthesis to harvest. It was found that melon plants grown in nutrient solution without potassium nitrate during anthesis to harvest produced fruits with an increased sodium concentration of about 56% (**Figure 2**).

79% by without potassium application during the latter half of growth period compared to control. These results suggest that it is possible to produce low-potassium spinach maintaining the normal plant growth. Other minerals like sodium and magnesium content increased with the decrease of potassium content, showing antagonistic role in osmotic pressure balance.

Introductory Chapter: Potassium in Quality Improvement of Fruits and Vegetables

http://dx.doi.org/10.5772/intechopen.75654

5

Lettuce is a popular potassium-rich vegetable usually eaten raw in the salad. CKD patients with hyperkalemia cannot intake large quantities of raw vegetables like lettuce, tomato, strawberry, etc. Therefore, producing low potassium vegetables would be highly appreciable from the viewpoint of dietary restriction. In this case, hydroponic culture systems have wide acceptability as it allows greater control over the root zone environment than soil culture, which makes nutrient management easy based on the plant requirements. Recently, low-potassium-content lettuce has been established by potassium fertilizer management [27]. Hydroponic culture systems have become widely used because they allow greater control over the root zone environment than soil culture, which makes nutrient management easy based on the plant requirements.

Potassium is the crucial macronutrient and main electrolytes in plants. Its requirement is higher than other mineral nutrients except for nitrogen, but some crops at their specific stages demand more potassium than nitrogen. Therefore, adequate potassium fertilization is necessary for enhanced and improved yield and qualities of agricultural produce. This monovalent cation interacts both antagonistically and synergistically with other nutrients. In hydroponic nutrient solution, it shows clear antagonism with sodium at its reduced levels. In this regard, management of potassium nutrient based on crop growth stage and following other culture techniques can produce specialty horticultural crops providing human health benefits. For example, low potassium content melon, strawberry, tomato, lettuce, and other leafy vegeta-

This book aims to enumerate available resources on potassium, its importance to plants yield and quality, management in the hydroponic culture solution, and cultivation techniques of production specialty horticultural crops. The content also discusses news ways of managing and developing sustainable production techniques and software for quality horticultural

1 Department of Agriculture, Faculty of Life and Environmental Science, Shimane

2 Olericulture Division, Horticulture Research Center, Bangladesh Agricultural Research

bles can improve quality of life (QOL) of CKD patients.

crops through potassium nutrition.

Md Asaduzzaman1,2\* and Toshiki Asao1

\*Address all correspondence to: asadcbt@bari.gov.bd

**Author details**

University, Shimane, Japan

Institute, Gazipur, Bangladesh

**6. Conclusion**

Strawberry is the most popular fruit in the world. This sweet-sour taste fruit rich in potassium attracts all aged people. However, elderly people suffering from chronic kidney disease are restricted to eat this fruit. In general, greenhouse-cultured fresh strawberries have a high potassium content of 170 mg/100 g FW of fruit [25]. In this regard, reducing this potassium level in strawberry fruit would remove the dietary restriction to CKD patients. Therefore, our research team also tried to produce low-potassium strawberries through the management of a KNO3 fertilizer in nutrient solution from anthesis to the harvest period. In strawberry plants that were grown in 1/32 level of KNO3 of the standard nutrient solution, fruit potassium was decreased about 23.5% compared to the typical level of potassium in strawberry fruit of 170 mg/100 g FW [25, 26].

Similar to melon and strawberry, tomato is a potassium-rich fruit vegetable. If low-potassium tomato fruit can be produced, it can improve the dietary options of dialysis patients and their quality of life. A method of producing low potassium content tomato fruit was investigated [27].

Hydroponic culture methods for spinach have been investigated with lower levels of potassium in the culture solution [28]. Spinach plants were grown hydroponically either with reduced potassium application throughout the growth period or without potassium applications during the last half of the growth period. No significant differences in fresh weight that were observed in plants cultured with either of the solution. However, the potassium content in plants was reduced as much as 32% by reduced potassium application throughout growth period and

**Figure 2.** Reduced potassium nitrates levels increases the fruit sodium content of netted melon grown in hydroponics (data not published).

79% by without potassium application during the latter half of growth period compared to control. These results suggest that it is possible to produce low-potassium spinach maintaining the normal plant growth. Other minerals like sodium and magnesium content increased with the decrease of potassium content, showing antagonistic role in osmotic pressure balance.

Lettuce is a popular potassium-rich vegetable usually eaten raw in the salad. CKD patients with hyperkalemia cannot intake large quantities of raw vegetables like lettuce, tomato, strawberry, etc. Therefore, producing low potassium vegetables would be highly appreciable from the viewpoint of dietary restriction. In this case, hydroponic culture systems have wide acceptability as it allows greater control over the root zone environment than soil culture, which makes nutrient management easy based on the plant requirements. Recently, low-potassium-content lettuce has been established by potassium fertilizer management [27]. Hydroponic culture systems have become widely used because they allow greater control over the root zone environment than soil culture, which makes nutrient management easy based on the plant requirements.

### **6. Conclusion**

culture solution was used for melon by reducing the potassium at lowest possible level. Therefore,

sis till harvest to investigate its impact on the fruit potassium content while maintaining normal growth, yield, and other fruit qualities. On the other hand, sodium concentration in melon fruits followed the reverse trend of potassium concentration. Its concentration increased significantly in

melon plants grown in nutrient solution without potassium nitrate during anthesis to harvest

Strawberry is the most popular fruit in the world. This sweet-sour taste fruit rich in potassium attracts all aged people. However, elderly people suffering from chronic kidney disease are restricted to eat this fruit. In general, greenhouse-cultured fresh strawberries have a high potassium content of 170 mg/100 g FW of fruit [25]. In this regard, reducing this potassium level in strawberry fruit would remove the dietary restriction to CKD patients. Therefore, our research team also tried to produce low-potassium strawberries through the management

sium was decreased about 23.5% compared to the typical level of potassium in strawberry

Similar to melon and strawberry, tomato is a potassium-rich fruit vegetable. If low-potassium tomato fruit can be produced, it can improve the dietary options of dialysis patients and their quality of life. A method of producing low potassium content tomato fruit was investigated [27]. Hydroponic culture methods for spinach have been investigated with lower levels of potassium in the culture solution [28]. Spinach plants were grown hydroponically either with reduced potassium application throughout the growth period or without potassium applications during the last half of the growth period. No significant differences in fresh weight that were observed in plants cultured with either of the solution. However, the potassium content in plants was reduced as much as 32% by reduced potassium application throughout growth period and

**Figure 2.** Reduced potassium nitrates levels increases the fruit sodium content of netted melon grown in hydroponics

fertilizer in nutrient solution from anthesis to the harvest period. In strawberry

produced fruits with an increased sodium concentration of about 56% (**Figure 2**).

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

concentrations from anthe-

supplied during anthesis to harvest. It was found that

of the standard nutrient solution, fruit potas-

melon plants were grown in nutrient solution with reduced KNO3

all the reduced potassium levels of KNO3

plants that were grown in 1/32 level of KNO3

fruit of 170 mg/100 g FW [25, 26].

of a KNO3

(data not published).

Potassium is the crucial macronutrient and main electrolytes in plants. Its requirement is higher than other mineral nutrients except for nitrogen, but some crops at their specific stages demand more potassium than nitrogen. Therefore, adequate potassium fertilization is necessary for enhanced and improved yield and qualities of agricultural produce. This monovalent cation interacts both antagonistically and synergistically with other nutrients. In hydroponic nutrient solution, it shows clear antagonism with sodium at its reduced levels. In this regard, management of potassium nutrient based on crop growth stage and following other culture techniques can produce specialty horticultural crops providing human health benefits. For example, low potassium content melon, strawberry, tomato, lettuce, and other leafy vegetables can improve quality of life (QOL) of CKD patients.

This book aims to enumerate available resources on potassium, its importance to plants yield and quality, management in the hydroponic culture solution, and cultivation techniques of production specialty horticultural crops. The content also discusses news ways of managing and developing sustainable production techniques and software for quality horticultural crops through potassium nutrition.
