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Potatoes in bunches

Aeroponic growing system creates a larger supply of seed potatoes for growers

APTA / IAC View from above of seed potato planting in greenhousesAPTA / IAC

Harvesting potatoes, a tuber that grows underground, as if they were grapes on a vine may seem strange. But this is what a Brazilian company is doing by putting into practice a technique brought to Brazil and adapted to the country’s tropical conditions by researchers at the São Paulo Agency for Agribusiness Technology (APTA) and Agronomic Institute of Campinas (IAC). This technique is aeroponics, a process in which, instead of growing underground, plant roots are suspended in the air. It is a variation of hydroponics, in which the root system of the plants is immersed in water. This technology is used to grow seed potatoes, which are minitubers used for growing more plants.

Aeroponics is found in countries such as the United States, Spain, Finland, China and South Korea, and it can be used for other crops, such as tomatoes, lettuce, cucumbers and strawberries. Commercial introduction of this technique in Brazil began in 2013, through a research project coordinated by engineer-agronomist Thiago Leandro Factor, a researcher at the Regional APTA Hub in Mococa. “Using materials that are easy to obtain on the market, we developed a system with commercial dimensions, good durability and easy handling, in addition to improving the nutritional content of the tubers for this type of crop,” says Factor. The study also resulted in the doctoral dissertation of agribusiness technologist Alex Humberto Calori, under the advising of agronomist Luís Felipe Villani Purquerio, of the Horticulture Center of IAC, who were part of the team.

These minitubers are grown in a type of dark box, in which the leaves are on top, outside the box, and the roots, where the seed potatoes grow, are inside it.  Between the exposed roots inside the box, there are nebulizers that release small drops of water with all the nutrients necessary for the plant to grow, at regular intervals. Along the sides of the box, made from PVC, there are sliding windows. “This way, it’s possible to harvest potatoes as if they were grapes,” says Purquerio.

“While we were conducting the project, we received visits from students and professors from several universities, as well as owners of companies,” says Purquerio. These included the owners of CBA Sementes, located in Divinolândia (São Paulo State), the first company to use the APTA and IAC technology. The system is also being used by two other companies: one in Mucugê (Bahia State) and another in Tapira (Minas Gerais State).

Potatoes are the third most important food of vegetable origin consumed by humans, behind only rice and wheat. For planting, seed potatoes are recommended, but they are one of the most expensive items for producers, accounting for between 15% and 30% of the production cost. The high price and low availability of adequate seeds in Brazil are factors that lead producers, mainly the smaller producers, to use material that is inappropriate for planting, such as very small potatoes that were not commercially used from the previous harvest. If they are infected, this promotes the spread of diseases, and over time, the quality of the crops worsens, and productivity falls.

APTA / IAC Under the growing tables, roots and minitubers grow, receiving water mixed with nutrients, by nebulizationAPTA / IAC

High productivity
The most common system for seed potato production is by seeding other seed potatoes in vases or planters, with topsoil and organic material, such as humus. Later, they are harvested to be planted in the field. This type of planting requires irrigation, application of fertilizers and pest control. Other techniques are aeroponics and hydroponics. Aeroponics has received attention because productivity can reach 50 or more tubers per plant, which is much higher than other systems, which do not go beyond seven. “Aeroponics reduces water use by 98%, fertilizer use by 60% and insecticide use by up to 100% when compared to traditional planting, directly in the soil or a seeder,” says Factor.

Most of the demand for seeds is met by material without phytosanitary approval from official government agencies or certification companies. For this reason, many producers turn to importing. “This is because farmers and specialized companies in Brazil cannot meet the demand,” explains Factor. “In 2016, 7.8 thousand tons of minitubers were imported for planting, at a cost of approximately US$ 9.1 million.”

“Our customers are potato growers looking for quality by using premium growing material,” notes Lucas Moreira, of CBA Sementes. “We are the first in Brazil to produce using aeroponics, with no contact between the crop and the soil.” According to Moreira, the company was founded using the technological base of IAC and APTA.

The aeroponic system does present some drawbacks however. These include the high initial cost of implementation, which is around R$600 per square meter. In addition, because of the automatic nebulizers, producers need to have a back-up generator for electricity production in the event the public electricity supply fails, or they risk losing the crop. “Since this is a recent technique–the first studies date from the 1980s–and was only commercially introduced in Brazil in 2016, aeroponics still offers a wide-open field for development and improvement with more studies, principally on the handling of the crop and plant nutrition,” adds Purquerio.

System development, evaluation of plant density and electrical conductivity of the nutrient solution in aeroponic production of seed potatoes (No. 12/50786-8); Grant Mechanism Regular Research Grant; First Projects Program (PPP) CNPq; Principal Investigator Thiago Leandro Factor (APTA); Investment R$136,937.62.