**4.1 Hydroponics**

The use of the hydroponics method in herbal production dates back many years. During the Babylonian period (605–562 BC), plants on the terraces were irrigated from the Euphrates River using pumps. It is understood from historical records that the Aztecs living in Tenochtitlan in the 40s BC produced plants on man-made islands by a method called chinampas, in which plants were directly in contact with water [30]. Until the present, chinampas have been producing 40.000 t/yr. of vegetables and flowers annually, consequently, the FAO recognized chinampas as a globally important agricultural historical heritage [31, 32]. As is known, hydroponic plant production systems are one of the fastest growing sectors in horticulture. The use of hydroponic crop production methods has increased by 20% worldwide between 2016 and 2019. In addition, the production value in dollar terms increased from 6.9 to 8.3 × 109 dollars in the same interval, and it is estimated that these values will increase up to 45% in 2025 [33]. In addition, the annual growth rate is estimated to increase by 6.8% between 2019 and 2024 in areas such as the United States, Canada, Germany, United Kingdom, China, Brazil, the Middle East, and South Africa [34, 35]. Strawberry is more popular than any other fruit in the world. Traditional strawberry farming, on the other hand, has major difficulties with productivity and plant loss due to soil-borne plant diseases. Besides, the chemicals needed to treat soil are quite toxic. That is why growers have opted for hydroponic strawberry cultivation. With this approach, the issues such as pest and disease control, high productivity in the field and good quality of the fruit are considerably achieved. In regions where the

climatic conditions are ideal, the soil is not a concern thanks to hydroponic farming. Soil-borne pathogens and the damaging impacts of pests are the main reason why hydroponics in greenhouse strawberry cultivation are demanded nowadays. Hence, owing to hydroponics, growers can increase yields and enhance product quality by using correct fertilization and water management [36–39]. For this method, producers have generally used the varieties such as Rubigen, Sabrina, Festival, and Albion.

Cocopeat is a growing medium used frequently by gardeners and especially for hydroponics. Cocopeat is made free from sand and out of coconut husk which is why it is appropriate for use in agriculture, particularly hydroponics. Thanks to its high water-holding capacity, %100 organic feature and pH of 5.7–6.5, Cocopeat is one of the best products to be used in agriculture. For the greenhouse cultivation of hydroponic strawberries, diagonal planting with 13 seedlings placed at 15 cm spacing is used for generally around 12 thousand seedlings per decare. Planting begins in October, with the first harvest occurring in December. This process continues until the middle of June. At the end of this process, approximately 10 tons of product can be obtained if suitable garden management methods are used and a correct plant nutrition program is implemented. Producers have become more aware of their production processes. Despite the ongoing rise in input costs, growers continue to crop since they still make a profit. Bumblebees are used to enhance pollination and fertilization, especially in greenhouse production. By avoiding the use of pesticides, bumblebees improve product quality while also contributing to natural production. Since the initial expense of growing strawberries in a greenhouse is so expensive, easiness, and productivity are critical. Strawberry production is generally limited to a sixmonth season, however, by using hydroponics in cultivation, this may be prolonged up to 12 months. Thanks to this benefit, fresh strawberries may be brought to market for a period of 12 months. When strawberries are properly cared for, production and efficiency in hydroponics may be four times higher than in traditional agriculture. Regardless of the significant initial investment, hydroponics has been used in the Mediterranean region by gardeners for the cultivation of strawberries in recent years.

This method is preferred since customers are prepared to spend the most and there is a lot of demand [40]. In addition, in greenhouse hydroponic strawberry cultivation, it was determined that frigo seedlings are advantageous in terms of yield and tubed seedlings are advantageous in terms of earliness [41]. Likewise, frigo seedlings are advantageous in terms of productivity and tubed seedlings are advantageous in terms of early maturing. Briefly, the productivity has been enhanced and fresh strawberries for the market have been available for over a year, thanks to the adoption of hydroponic technology in the strawberry greenhouse culture. Moreover, with this approach, plants have been protected from soil-borne pathogens and pests while the nutrition they provide has been boosted [4].

Hydroponic systems can technically be classified into two groups. The first is open systems that provide nutrients directly and once to plant roots, and the other is closed systems that provide a continuous and cyclical supply of nutrients to plants. In addition, the nutrient solution given once in open systems comes into contact with the plant roots continuously or occasionally. The media substrates and nutrient solutions used in this system are used only once; that is, they are not reused. Some advantages of open systems are that the plant nutrition solution application is simpler and the risk of infection is less for the plant [42]. In closed systems, plant nutrition solutions are applied to the plant roots, which are given alternately to the plants and collected in containers, as a liquid substrate or as a liquid solution. Substrates used can be organic (such as coconut fiber, rice husk, sawdust, and charcoal) or inorganic (pumice, sand,

#### *Strawberry Cultivation Techniques DOI: http://dx.doi.org/10.5772/intechopen.104611*

gravel, and ground brick). In this plant production method, the use of water and nutrients is generally the best, and the disadvantage is the need for electricity [35, 43]. However, in recent years, attempts were made to minimize these disadvantages by using renewable energy. Furthermore, additional applications such as sufficient oxygen uptake of plant roots, suitable temperature environment, adequate nutrient supply, and increasing the activity of beneficial microorganisms for the plant are rapidly applied. Thus, smart farming methods are used in soilless culture in order to understand and follow the communication between plant roots and shoots in strawberry plants in a deeper and more detailed way, and as a result, new technologybased trends were developed to improve plant roots [44]. In another research, strawberry production was carried out using a hydroponic system in tunnel greenhouses to protect against the harmful effects of rain. In this study, a significant increase in yield was achieved by protecting plants from the harmful effects of rain and reducing disease and pest pressure [45, 46]. Hydroponics is a fairly new method that can produce products in and out of season under fully controlled conditions without soil. As is well known, plant feeding and fertilization processes are carried out entirely through the irrigation system in this production model.

In agricultural production, applications such as hydroponic production, vertical agriculture, or soilless agriculture are also increasingly popular for strawberry production [47, 48]. Production methods of vertical farming and hydroponics can be applied in smaller areas and use 95% less water and nutrients than traditional strawberry production methods [49]. At the same time, hydroponic production methods are more advantageous than other methods, since production can be closer to consumption centers in arid and semi-arid conditions regardless of soil quality [50]. Besides, this production model has many advantages such as more efficient and correct use of water management, production throughout the year, higher yields and minimizing the use of pesticides compared to soil culture [51]. It is extremely important to apply for an accurate and effective plant nutrition program in strawberry production with the hydroponics system. In this system, remote-controlled automation systems have been used in strawberry and tomato production in recent years [52, 53]. In this method, the properties of irrigation water and the accuracy of these properties are extremely important. In remote sensing systems, the turnkey solution collects information about the growth of plants in soilless strawberry cultivation and makes predictions accordingly. Previously, a compact sensor with an oscillator circuit was used to monitor the irrigation status and concentration of fertilization of the plants [54]. Moreover, there was a noticeable increase in the use of light emitting diode (LEDs) technology in strawberry production in recent years. Some researchers report that LED lights can be used alone or in combination with other light systems to increase plant behavior, yield, and fruit quality. In a study conducted for this purpose, three different light systems (LED blue, LED red, and fluorescence neon tubes as control) were used to evaluate the effect on plant growth and fruit quality in soilless strawberry production. According to the results, blue LED light with a wavelength of 400–500 nm promotes biomass accumulation, especially at the root and crown level. In addition, fruit set (65 g plant−1) in plants treated with blue light was 25% higher than plants in the control group (45 g plant−1) and with red light (35 g plant−1). There was no change in the main quality traits of the fruit, but it was determined that the color and anthocyanin amounts were low as a result of both applications. As a result of this study, it was reported that the use of blue light increases fruit yield by keeping fruit quality stable [55].

Since the plant nutrient solution is used repeatedly in closed hydroponic systems, root exudates, which have an intraspecific allelopathic effect, accumulate in the

strawberry roots over time and inhibit plant growth by causing an autotoxic effect on the plants. In a study, electro-degradation (ED) was applied to the culture solution in order to degrade these root exudates in strawberries and to increase fruit yield and quality. During this application, four types of nutrient solutions were applied. These include renewed, non-renewed, and non-renewed with direct current electrode gradation (DC-ED) and finally non-renewed with alternative current electro-degradation (AC-ED). While 25% standard Enshi nutrient solution was added to the culture solutions which were renewed every three weeks, DC- and AC-ED were applied to the non-regenerated solutions. It was reported that the fruit yield obtained with the renewed solution (225.9 g plant−1) and the yield obtained from the non-renewed and AC-ED solution provided statistically similar results. Fruit yield was decreased to approximately half (114.0 g plant−1) in the non-renewed solution compared to the renewed solution, but plants treated with the non-renewed solution with DC-ED produced an intermediate yield between the non-renewed and renewed solution. The growth performances of the plants treated with the renewed nutrient solution were higher than the plants treated with the non-renewed solution with DC-ED. Briefly, it was indicated that nonrenewed and AC-ED nutrient solutions may have a positive effect on fruit development, yield, and quality in strawberries [56]. In addition to the hydroponic method mentioned above, new methods such as vertical farming are also used in strawberry production.

### **4.2 Vertical farming (VF) in strawberry production**

In recent years, the area of arable land has been declining gradually due to the increase in the human population, urbanization, pollution, and soil erosion. While the world population living in urban areas is 60%, it is estimated that this rate may increase to 68% in the 2050s with the increase in immigration in the 2030s [57, 58]. Vertical farming will be an important factor in solving problems occurring due to these challenges. Regarding advanced farming techniques such as vertical farming, controlled-environment agriculture is performed so that high yields are obtained by using fewer resources in a restricted area [54, 59, 60]. Unfortunately, industry-based agricultural practices disrupt the natural structure of the soil and increase the erosion rate (10–40 times). Moreover, according to some studies, it is estimated that these agricultural production methods can reduce clean water resources by about 70%. However, in VF applications, high-efficiency production can be achieved using much less water and space. It was stated, for example, that a Japanese agricultural tool named Mirai provides information on 25.000 m<sup>2</sup> of the indoor agricultural farm to producers and academics. This agricultural vehicle provides 40% energy and significant water savings [61]. As a leader of VF, the aviation farm has increased the agricultural product yield of New York by 390 times and 95% water savings [62]. Carbon dioxide is a very vital factor in agricultural production. As a result, a new toolkit was built with wireless communication that can be handled by mobile phones to properly determine carbon dioxide estimation in vertical farming. Moreover, these devices provide automatic observation for all developmental stages of plants [63, 64]. In recent years, hydroponic vertical farming has become the most advanced, environmentallyfriendly agricultural production technique that does not harm biodiversity. Ways to achieve this are to focus on deserts, which make up one-third of the world. Based on this idea, Chinese and Norwegian experts are currently working on the application of these production methods in the deserts of Dubai, Qatar, Jordan, and China. The most important argument for achieving this goal is the use of technologies such as IoT [65, 66]. In recent years, due to negative factors such as climate change in agricultural lands, pollution of soils due to the intensity of agricultural practices, use of agricultural lands as settlement areas, and deterioration of soil structure, plant production companies, or their investors have pioneered the use of horizontal farming techniques, which is a different and alternative method for strawberry production.

### **4.3 Using horizontal systems in strawberry production**

Horizontal systems can be on the ground or have the potential to be stacked on top of each other. Since fruit harvesting and other agricultural tasks are easier at breastor neck height, horizontal systems are preferred. Containers, pots, bags, and gutters can be used as a medium for plant growth. Since the plants need regular irrigation and fertilization, the preferred environments for growing plants should have sufficient depth and high water-holding capacity. In this method, in contrast to field production, the ability to store water and nutrients is limited. It was reported by experts that the use of galvanized metal, which cause high concentrations of zinc accumulation, should be avoided as a plant-growing medium. In this system, as the plants grow, they make use of wire and other support systems so the plants can stand upright to provide convenience during harvest [67]. In addition to the use of hydroponics, vertical farming, and horizontal systems in strawberry production, there has been an increase recently in the use of quite new techniques such as robot technology, artificial intelligence, and machine learning in the harvesting process.

## **4.4 New harvesting techniques used in strawberry production**

As is known, harvesting is one of the most important criteria in determining product quality and productivity in agricultural production. It is reported that 3.1 billion USD product loss is expected every year in the USA due to the lack of qualified manpower [68]. According to data from the United States Department of Agriculture, 14% of agricultural input costs are spent on manpower. At the same time, the labor cost in industrial agriculture can reach up to 39% [69]. Deep studies are still needed about the production of more specific sensors for the effective use of automation systems in fruit harvesting. For example, strawberries are berry-like fruits that can be consumed in any season of the year. However, the use of manpower in strawberry harvesting and packaging processes is one of the most effective factors in increasing fruit prices [70]. Since the strawberries grown in greenhouse conditions are harvested with robotic harvesting technology, the cost is reduced. A robot named Agrobot was developed for this harvesting process and this robot can harvest and pack strawberries from rows of plants [71]. For example, Agrobot's SW 6010, which is a semi-automatic robot model, was reported to provide significant convenience in strawberry harvesting. Another example, Tektu T-100, is another strawberry harvesting robot model that can be charged with electricity and is environmentally friendly [70]. In recent years, due to the decrease in qualified personnel and manpower in agricultural production, the necessity of minimizing losses during the harvest, and reasons such as time and cost savings force farmers to use agricultural robotic technologies. Recently, some researchers reported that fruit-picking robots are being developed by private companies rather than academic researchers. Moreover, the problems in seasonal fruit picking jobs necessitate the use of automation systems in fruit harvesting. In the last 5 years, there was a significant increase in the number of companies producing fruitpicking robots. Advanced vision systems, image processing techniques and artificial

intelligence are used in the harvesting of berries, pome fruits, apples, and stone fruits. For example, the mobile robot can pick up strawberry fruits growing on strawberry pads several feet above the ground and can sort them by size or weight and place them in fruit baskets as they move. RGB (Red-Green-Blue) cameras with three-dimensional (3D) features are used to determine the position and ripening times of the fruits. The robot gently harvests with the help of an arm that imitates the human arm extending from the bottom up, has padded soft-grip plastic claws and can rotate 90° to pluck the fruit from the stem. It can harvest soft fruits at a rate of 11.500 berries (between 180 and 360 kg) in a 16-hour day, well beyond the 50 kg typically collected by a human [72]. In light of this information, it is expected that there will be an increase in the use of robotic technologies in fruit harvesting.

In this context, many studies were carried out around the world. A deep learning algorithm, Rotate-YOLO (R-YOLO) was developed to perform real-time location and harvesting of strawberries regarding a strawberry robot technology that performs the strawberry harvest. In addition, with the help of the bounding box, it accurately detects the plucking point with an angle to follow the direction of the strawberry and harvests it gently. It was reported that the robot, customized for the harvest of ridge-planted strawberries, with fiber sensors on its end-effector to control its speed, avoids real-time distance measurements. As a result, the researchers stated that the robot using Rotate-YOLO (R-YOLO) was successful in correctly identifying strawberries at a speed of 0.056 per second, with a 640 × 480 resolution RGB camera and a rate of 94.43% [73]. Furthermore, the monitoring system used in the strawberry harvest monitors the ripening time of the strawberry, reduces possible injuries during the harvest and detects diseases and pests at the right time. Therefore, the strategic advantages of agricultural production are implemented in different strawberry production applications by using innovative technologies. Experts are working on a system that can monitor strawberry cultivation in real ecologies, as well as access more accurate information about the harvest time of the strawberry plant and make the right decision. The system recommended above has a design that analyzes and stores the climatic data for the strawberry and images recorded through the IoT-Edge-AI-Cloud concept [74, 75]. The IoT-Edge device, Arduino and Raspberry Pi will be sufficient to install such systems at affordable costs. Even if the strawberry producer expands their production area, the system operated through AI-Cloud can easily be expanded as well according to the purpose and demand. The system can effectively evaluate the climate data in strawberry cultivation by reasoning with an artificial memory of the maturity stages of the strawberry plant. All data obtained in strawberry production (such as harvest time, disease detection, and production data) are analyzed by evaluating the data transferred to the integrated interface. In a study, ecological data and images of strawberries from hydroponic strawberry production were obtained using the IoT-Edge module and transferred to a nano-sized private AI-Cloud-based analysis station module and visualized to determine when to harvest. The monitoring and analysis results were envisioned with an integrated interface supply for major data such as fluctuating yields, harvest periods, and pest diagnosis. The suggested system is based on the idea of AI-Cloud. This concept helps server container to be scaled up quickly and simply as it grows. The suggested system was put to the test in a home where Seolhyang strawberries were grown using hydroponics. Over the course of four months, 1.316.848 actual environmental data points pertaining to 13 data kinds were monitored. Using 1575 strawberry photos from the Smart Berry Farm and a Google Images search, the harvest time was predicted with a high accuracy rate of 98.267% [76].
