Use of tomato rootstocks as a measure to increase productivity and combat diseases

The use of commercial tomato rootstocks has become popular, because in addition to protecting the plant against soil-borne diseases, it increases the vigor and productivity of the crop. Grafting – as the technique is known – is a propagation method that consists of fusing tissues from two different plants, the purpose of which is to explore the desirable characteristics of each one. In general, the lower part (rootstock) contributes to the roots and the lower area of ​​the stem, being responsible for supporting the plant, absorbing water and nutrients and adapting to soil and substrate conditions. The upper part (the graft) will help the stem, leaves, flowers and fruits.

In Brazil, according to Embrapa (Brazilian Agricultural Research Corporation), the first records of the use of grafting in vegetable cultivation date back to the 50s, in the northern region of the country. Japanese immigrants who lived in Pará grafted tomato plants onto "jurubeba juna" – a plant native to the region – as an alternative to control bacterial wilt. Caused by the bacterium Ralstonia solanacearum, it is one of the most important and destructive diseases of tomato, especially in tropical and subtropical conditions, with serious epidemiological implications and devastating economic consequences in commercial tomato fields, severely limiting the productive capacity and sustainability of the business. of the affected host species.

This pathology attacks a wide number of plant species, assuming special importance for causing damage to crops of great economic and social relevance, such as potatoes, peppers, bananas, eggplants and tobacco, as well as some cucurbits such as cucumber and zucchini. A highly effective measure is the use of tomato rootstocks with high tolerance to certain biovars of Ralstonia solanacearum, which is known to be a soil-dwelling pathogen, persisting for several years, and which presents great genetic, biochemical and Virulence. The bacteria penetrate the plant from the root system through wounds or natural openings. Thus, it colonizes the xylem, causing wilting as a reflection of vascular dysfunction, which only occurs due to the multiplication of bacteria, which ends up leading the plant to death.

An example of a generative rootstock that has shown good results as one of the measures in disease management is Shincheonggang, an exclusive product from Seminis (Bayer's fruit and vegetable segment). Recently introduced on the market, it is also resistant to race 3 of Fusarium wilt and root-knot nematodes.

The ideal age for grafting is 18 to 30 days after sowing, depending on the technique adopted and climatic conditions. Another excellent feature is that it provides better phytosanitary management of soil diseases, adopting greater safety when carried out within an integrated management program, enabling the cultivation of tomatoes within commercial standards, increasing the producer's profitability.

The magazine Plant Pathology & Quarantine recently published a scientific article that discloses data from a test carried out on a tomato plantation, using the Seminis rootstock in an area contaminated by Ralstonia solanacearum, carried out with the aim of measuring productivity and incidences that this disease causes.

The experiment was carried out in blocks with 20 plants highly infested by the bacteria, during the 2018-2019 season, at EPAGRI (Agricultural Research and Rural Extension Company of Santa Catarina), and the results were visibly positive, proving how much the use of the Rootstock can be an excellent alternative to combat the disease. The first symptom of tomato bacterial wilt appeared 20 days after transplanting and all plants that had the rootstock performed better when compared to plants that did not have it. The grafted plants were also capable of producing tomato fruits within commercial standards.

To better understand the real extent of the Shincheonggang rootstock's effectiveness in the tests, it is necessary to analyze the numbers obtained. Therefore, we have to understand the classification adopted for the sizes in grams of Compack tomatoes, being “A extra” for fruits weighing between 100 and 150 grams and “AA extra” for fruits weighing more than 150 grams.

Plants with the Shincheonggang rootstock were capable of producing 29.522 fruits classified as “A extra” and 68.524 “AA extra” fruits per hectare. This all shows us that the rootstock is one of the main components of the production system that can directly and indirectly affect the productivity and quality of tomato plants.

By Marcelo Tavares, marketing manager for the Seminis brand, Bayer's produce arm in Brazil