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Viticulture

A lot of pulp and no seeds

Three varieties of seedless table grapes adapted to the tropical climate are launchedonto the market

EMBRAPA UVA E VINHOGreen BRS Linda variety launched by Embrapa: neutral flavor, to the taste of the EuropeansEMBRAPA UVA E VINHO

They can be defined in a few words: succulent and without those bothering pips in the middle of the pulp. They are three varieties of seedless table grapes, one red and two green, which will be launched in Jales, a municipality in northeastern São Paulo, on the 19th of this month, at the Tropical Viticulture Experimental Station of the Brazilian Agricultural Research Corporation (Embrapa). The presence of this kind of fruit is not a novelty in the greengrocers and supermarkets. But the new varieties of seedless grapes are different from the seedless strains planted in the country, like Thompson, Festival and Centennial. The result of a work of genetic improvement by a traditional method that started seven years ago, three strains were developed to flourish in Brazilian climatic conditions, warmer than the majority of the vineyards in the world. “Handling them is simpler, and their productivity greater than that of the varieties from colder regions”, says researcher Umberto Almeida Camargo, from Embrapa Grapes and Wine, located in the city of Bento Gonçalves, Rio Grande do Sul, who is coordinating the works with the seedless grapes.

Strictly speaking, the new varieties are not totally devoid of seeds. They have vestiges of these germinative structures. In the red grapes, they are like traces in the form of one or two pink spots in the inside of the pulp. In the green strains, it is more difficult to see these little spots. “But these traces are as soft as the pulp of the fruit and you don’t feel their presence in your mouth”, Camargo guarantees. It is interesting to note that Embrapa’s cultivars descend from varieties that already were devoid of seeds naturally. After being fecundated, the seedless plants generate embryos, as happens in any other plant. But when about eight weeks have elapsed since fertilization, a spontaneous abortion occurs. This is an event that makes the formation of seeds inviable, because the embryo (which is the fusion of the paternal and maternal genetic material) remains lodged inside this germinative structure.

In the test tube
But, then, if the embryo resulting from crossing two seedless varieties does not develop successfully, how is it possible to create new cultivars using seedless plants? The solution is a technique called embryo rescue and in vitro cultivation. Six weeks after the fecundation of the vine, shortly before the natural abortion of the embryo, the grapes, still immature, are picked. The embryos are removed from the berries and put into test tubes with a nutritive medium that is adequate for them to complete their development and germinate in the laboratory, to be transferred to the field afterwards. This is the way how the generation occurs of a possible new variety of grapes derived from seedless parents. Besides making cross-breeding viable between seedless plants, the technique makes it possible to incorporate in the new variety, right in its first generation, other desirable attributes, such as the flavor, texture and size of the berries. The process for generating a new cultivar also includes patient work on acclimatization and plant reproduction (asexual propagation) by cuttings, under Brazilian field conditions.

Embrapa in Bento Gonçalves has a collection of germplasm (reproductive material) of 1,231 species of vines, for use in genetic improvement projects, and has developed eight selections of seedless grapes. These selections are cultivated in an experimental manner by producers from six Brazilian regions: Pirapora, in Minas Gerais, Petrolina, in Pernambuco, in the São Francisco valley, Marialva, in the north of Paraná, Limoeiro do Norte, in Ceará, besides Jales and Bento Gonçalves.For the time being, three of these selections have heartened Embrapa to launch them as new cultivars. It is interesting that each one of them shows particular characteristics. The red strain, for example, is very aromatic, has a bittersweet taste and high acidity. One of the green strains has golden yellow berries and, as its hallmark, its extreme sweetness, much to the taste of the Brazilian consumer. “This grape is not for any diabetic to eat”, jokes agronomist Sérgio da Costa Dias, from the Pirapora Agricultural Cooperative, who planted, on an experimental basis, 1.5 hectares of vineyard with the new strains. The third variety has a very green skin and is the opposite of the previous green caste: its flavor is neutral, with low levels of sugar and average acidity. It is almost a light or diet grape, and it should please the European consumer. This grape has been given the trade name of BRS Linda. The sweet green grape is BRS Clara, and the dark one, BRS Morena.

Adapted to the environment. In terms of yield per area planted, the production of the new grapes is at least 20% superior to that of the castes of imported origin. Another positive point is the lower cost of their handling. “I need four employees per hectare, when I work with Embrapa’s varieties”, says Tarcísio Bezerra, the manager of Sant’Ana Farm, in Petrolina. “With Festival (an imported caste), six employees are needed.”Since its start, the seedless grape genetic improvement project has received investments in the order of US$ 2.8 million. Three quarters of these resources have come from Embrapa’s own cash, a bit less than 20% came from the National Council for Scientific and Technological Development (CNPq), and the rest from producers cooperatives and agricultural companies. Laying bets on researching (and cultivating) seedless table grapes is a good way for fattening the country’s exports. In Europe, the price of a kilo of seedless grapes can reach US$ 3.50. Today, the estimate is that only 3% of the 600,000 tons a year of table grapes produced in the country are from seedless castes. Of this total, only 26,000 tons were exported in 2002, yielding US$ 34 million.

The production of seedless grapes during almost the whole of the year may increase the presence of the Brazilian grape in Europe and in other markets. This is possible because in the São Francisco valley, a semi-arid region where irrigated fruit growing is developing by leaps and bounds, up to two and a half crops a year of grapes are harvested. This peculiarity guarantees an almost uninterrupted supply of the fruit. In the south of the country, just as in the traditional table grape exporting countries, there is only one harvest a year, generally in the summer months. “Another advantage is that seedless grapes are ideal for making raisins”, Camargo notes. Today, the raisins that are much appreciated at the end of year festivities all come from abroad.

The project
Creation of Seedless Grape Cultivars for Brazilian Table Grape Growing; Coordinator Umberto Almeida Camargo Embrapa Grapes and Wine; Investment US$ 2,150,000.00 (Embrapa), US$ 430,112 (CNPq) and R$ 240,000.00 (private enterprise)

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