Agriculture Reference
In-Depth Information
vinifera
is limited to areas with an average
annual temperature of 10°C and a vegetative
cycle (the period from fl owering to harvest) of
at least two hundred days. Clearly, Italy's gener-
ally temperate, Mediterranean climate allows
vinifera
to thrive. While ssp.
sativa
performs
best in relatively dry climates, ssp.
silvestris
can
tolerate more humid conditions that mimic the
woodland and marshy environments it calls
home; both however are highly heliophilic, in
that they need plenty of sunlight (and in fact
wild vines prefer to live at the forest's edge or
near clearings). The two subspecies differ con-
siderably in a number of other aspects as well,
such as the size and shape of their leaves,
bunches, pips, and berries. The bunches and
berries of ssp.
silvestris
are smaller and fewer,
and their grapes are almost always darkly hued;
there are very few white grapes in the wild.
Wild grapes are also less sweet and higher in
acidity, and have larger and rounder pips.
However, larger bunches and better-tasting
berries are not the only advantages of the culti-
vated
vinifera
subspecies. Wild subspecies are
dioecious, having male and female plants with
unisexual fl owers. Though there are functional
exceptions, the domesticated
vinifera
is instead
an hermaphroditic plant, bisexual, with sex
organs that are both male (stamens that produce
pollen) and female (pistils containing ovaries to
be fertilized). Therefore, it can self-pollinate, and
every plant can bear fruit: not a small advantage,
and one that may explain why our farming ances-
tors might have preferred to cultivate vines rather
than tend wild ones. Interestingly, a small per-
centage of ssp.
silvestris
vines are naturally her-
maphroditic, paving the way for domestication of
what was initially only a wild grapevine species.
Between 10,000 and 7,000
B
.
C
.
E
. all
vinifera
grew wild, and the grape varieties we know
today evolved from them. Grape varieties are
the result of sexual reproduction between two
parent varieties: a fl ower is pollinated or ferti-
lized, leading to the formation of a berry and its
seeds. The seeds are then propagated in a
number of different ways and new vines are
born. Self-pollination occurs when the pollen
reaches the same fl ower it originated in, or a
fl ower on the same vine, or a fl ower on a differ-
ent plant of the same variety. Cross-pollination
happens when the pollen from a fl ower from
one variety reaches a fl ower from another vari-
ety. Clearly, the latter was a great deal more
common in times past, when different varieties
were planted in the same vineyard.
Most likely, the fi rst grape varieties were wild
vines that adapted over time to new
terroirs
via
human efforts to cultivate them. In a phone
interview with Attilio Scienza of the University
of Milan, he told me that cross-pollination not
just between cultivated varieties but also between
wild vines and the earliest cultivated species also
seems likely. Though some DNA-based studies
reject the possible genetic relationships between
cultivated and wild grapevine species (This,
Lacombe, and Thomas 2006), others disagree
and cite Italian native examples such as Sardin-
ia's Bovale Piccolo and Veneto's Oseleta, which
have been shown to have a high genetic affi nity
with local wild vines (Grassi, Labra, Imazio,
Spada, Sgorbati, Scienza, and Sala 2003; Zecca,
De Mattia, Lovicu, Labra, Sala, and Grassi
2009 ). According to a report by Di Vecchi Staraz,
Bandinelli, Boselli, This, Boursiquot, Laucou, et
al. (2007), seven Tuscan native varieties have
important genetic relationships with wild grape-
vines. Due to the large differences observed
between members of a few individual grapevine
species (for example, Sangiovese), some experts
have also postulated the existence of grapevine
“variety-populations” via a mechanism of poly-
clonal inheritance, originating from several dif-
ferent grape seeds. The existence of these was
hypothesized by Levadoux in the mid-twentieth
century and again by Mullins and Meredith in
1989, and has been championed in Italy for For-
tana and Glera (Silvestroni, Di Pietro, Intrieri,
Vignani, Filippetti, Del Casino, et al. 1997; Calò,
Costacurta, Cancellier, Crespan, Milani, Car-
raro, et al. 2000). This is currently a minority
hypothesis, with most experts believing that
every grape variety originates from a unique
seed with just two parents (for example, a single
seed is at the origin of Sangiovese).
