2. Hydroponic system cultivation

According to Embrapa [1], protected cultivation allows farmers to offer the market products with good visual quality in periods of low supply and high prices, contributing to a good profitability, which justifies the investment with the protected structures. Brazil has more than 30,000 hectares of protected cultivation, being the country with the largest cultivated area in this system, in South America.

Protected cultivation, which has the potential to double the productivity reached in the open field, emerges as a technique capable of reconciling high yields with quality in environmental conditions that are potentially stressful to plants and may compromise the production of vegetables. In the last two decades, the protected crop, worldwide, increased 400%, from 700,000 to 3.7 million hectares. The use of hydroponics in protected crops has been used as a tool to solve a wide range of problems, including the reduction of soil and groundwater contamination, and the nutritional biofortification of olive trees [2].

Among the several hydroponic systems that do not use substrates, "Nutrient Film Technique-NFT" is the most widespread in Brazil and in the world [3]. This technique favors the continuous or intermittent circulation of the nutrient solution in culture channels, which can be varied in size and made by different materials, being the most common PVC, polyethylene, polypropylene and masonry [4]. In this agricultural production system, there is still a need for the development of new technologies, notably the need for new software to assist the producer in calculating the nutrient solution [5], since the correct calculation of the nutrient solution is fundamental for success in production. The supply of nutrients at levels suitable for growth, minimizing production losses and providing better quality to fruit vegetables [6]. With the use and advancement of information technologies in the development of software for the Internet, IT stands out as a cross-cutting area for all sectors, gaining its space in agriculture, increasing competitiveness and optimizing production [7].

Hydroponics is an off-the-ground crop technology that promotes the diversification of activities related to agribusiness, as it generates a differentiated product of good quality and of great acceptance in the market, although it cannot be certified As organic cultivation, since hydroponics is not a natural method of cultivation [8, 9]. It is a technique of cultivation in protected environment, in which the soil is replaced by the nutrient solution, in which are contained all the nutrients essential to the development of the plants [10].

Hydroponics has been growing substantially in Brazil, driven by the demand of the consumer market for differentiated vegetables, as well as the higher value added to the product, thus generating significant growth in the hydroponic cultivation of fruit and leafy vegetables [3]. This technique has many advantages over traditional soil cultivation, as it eliminates traditional agricultural operations, such as requiring less human effort, lack of competition for plants for nutrients and water, significant increase in productivity, precocity in the harvest and less occurrence of phytosanitary problems, with less application of pesticides, which generates a better final product quality [11].
