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CENTURY-OLDPRACTICE
Grafting is a propagation method that consists in uniting a shoot or bud with a
growing plant by insertion, with the aim to explore the desirable characteristics of
both of them. The lower portion, known as grafting stock, contributes with the roots
and with the lower portion of the stem, responsible for sustaining the new plant,
through the absorption of water and nutrients and for adapting the plant to the soil
conditions or to another growing medium. The upper portion (graft), which consists
in the commercial segment, consists of the stem, flowers, leaves and fruits. The favo-
rable characteristics of the two plants are expressed in one plant.
Although the technique has been known for many centuries, vegetable grafting
was first practiced in Japan, in the 1920s. In Brazil, the first records of this practice date
back to the 1950s, in the North, where Japanese immigrants in the state of Pará graf-
ted a tomato plant on a native species for keeping bacterial wilt under control. Due
to the high cost of the grafting system, the farmers switched to other crops. Modern
research works have renewed an old practice with more technology and tools and,
due to it, it is pointing to a new scenario for the tomato crops in this Brazilian region.
A prophet in his own land
Graftingtomatoplantscouldbeagoodhelpincontrollingbacterialwilt
andseemstopavethewayfornewproductivechancesfortheAmazonregion
Commercial tomato crops in the Ama-
zon region are a real challenge. High tem-
peratures and wet soils favor the develop-
ment of pests and soil-borne diseases, both
in the open and in protected cultivation,
like nematodes, bacterial wilt and Fusarium
wilt. Agronomic engineer José Lindorico de
Mendonça, from Embrapa Vegetables, ex-
plains that even commercial cultivars glob-
ally known for their resistance to diseases,
end up infected by bacterial wilt in the Am-
azon region, requiring highly resistant graft-
ing stocks for this region.
Mendonça, with a PhD degree in Phy-
totechnics, says that several studies un-
derway are focused on the use of the
genetic diversity of the plants of the Am-
azon region for changing this reality. The
resistance of nightshades, solanaceous
plants, to soil-borne pests, present prom-
ising results compared to the resistance
sources in tomato plants. “Tomato bacte-
rial wilt is the main soil-borne disease in
protected crops in Brazil because the en-
vironmental conditions in this cultivation
system (high temperature and moisture)
favor the development of Ralstonia sola-
nacearum, bacterium that causes the dis-
ease”, he says.
Mendonça maintains that the seed mar-
ket for grafting stocks is furnished with
sufficient amounts of tomato hybrids re-
sistant to multiple soil-borne diseases, ex-
cept for the Amazon region, where even
these resistant species are badly affected
by soil-borne pests. In regions with a high
concentration of protected crops, like
Santa Cruz do Rio Pardo, in the interior
of São Paulo, grafting is successfully used.
With regard to nematodes, which cause
losses to tomato crops, a new breed has
surfaced and it has no resistance source
in the available tomato cultivars: it is
known as Meloidogyne enterolobii.
“Some research works have already
identified resistance sources in wild spe-
cies of the solanaceous family, which could
be used for the development of grafting
stocks or resistant hybrids”, he clarifies.
Some of these species present multiple
resistance to all major soil-borne pests.
The trend is for the finding to change
the reality in the Amazon region, which
could encourage local tomato produc-
tion – most tomatoes are still imported
from other regions in Brazil, from plac-
es as far away as 2,000 kilometers, with
higher prices because of logistics.
