Production Practices and Quality Assessment of Food Crops. Vol. 1

Chestnut, an Ancient Crop with Future 113
width ranged from 2.0 to 11.3 cm (4.5 cm on average) (Table 5). The widest point
in the leaf is localised at 7.6 cm from the base. Petiole length is 1.7 cm on average,
with 0.5 cm the minimum and 3.8 the maximum. Leaves present 17 secondary
veins forming a 47° angle with the main vein, but only 15 finished in incisions of
margin.
Burs bear two chestnuts on average and the third in the middle usually does
not develop, though occassional burs present up to six normal chestnuts. A normal
nut by bur was 66% on average (Table 5). Each bearing shoot presents two burs,
but occasionally has up to eight. Spines length is 1.23 cm on average, but is highly
variable (Pereira-Lorenzo et al., 1996a and c) (Figure 3): (1) few cultivars (14%)
showed long spines of 1.56 cm on average. (2) Most of the cultivars (68%) showed
medium size of 1.23 cm on average. (3) 19% of Galician cultivars presented short
spines of 0.95 cm on average. Most of the burs appeared at the end of the bearing
shoots (77% of the samples).
Lateral and central nuts in the bur are significantly different in most of the
parameters (Pereira-Lorenzo et al., 1996c). Lateral nuts are longer, broader and
thicker than central ones. Average style length was 0.9 and 0.8 cm, respectively.
Variation in weight has been taken in account in selection of cultivars. Smaller
nuts can be considered under 10 g, medium between 10 and 15 g and large one
over 15 g (Figure 4).
In Galicia (North-western Spain), the mean weight of the central nuts was
10.1 g, and 11.1 g for lateral ones, with a kernel percentage of 76 and 77%,
respectively.
Average number of nuts per kg for Galician cultivars (North-western Spain)
was 106 (Table 5) versus 73 in Andalucía (South Spain) (Pereira-Lorenzo and
Ramos-Cabrer, 2002), though sizes of the nuts do not appear to be related with
latitude, since in both areas cultivars producing big nuts are cultivated. However,
in the South they have mainly propagated cultivars with larger nuts. In Galicia,
less than 30% of the nuts are over 32 mm, though some cultivars produce more
than 50% of nuts over 36 mm. In the Canary Islands, some cultivars such as
Arafero produce 70 nuts per kg while De Sala, Del Haya, or Donosa produce more
than 100 nuts per kg (Pereira et al., 2001b).
Normal nuts can vary from 1.2 cm to 4.3 cm in length, 1.0 cm to 4.7 cm in
width and 0.7 to 3.9 cm in thickness. The mean values for both lateral and central
nuts being 2.8–2.9, 3.2–3.3 and 1.8–2.0 cm, respectively (Table 5). Hilum size
can vary between 0.3 × 0.7 cm to 1.3 × 2.0 cm in central nuts and 0.3 × 0.9 cm
to 3.0 × 4.1 cm in lateral ones.
Five types of shapes are defined in chestnut, according to the relationship between
the width and the length of the nuts (WL = Width/Length*100) in (1) triangular
(WL < 100), (2) round (WL = 100), (3) elliptical-triangular (100 ≥ WL < 110),
(4) elliptical short (110 ≥ WL < 120), and (5) elliptical broad (120 ≤ WL)
(Casabianca and Vincensini, 1981) (Figure 5). These shapes have been used in
classification of chesnut cultivars in France and Spain (Casabianca and Vicensini,
1981; Pereira-Lorenzo et al., 1996a).
Penetrations of the inner coat in cotyledons can be upto the depth of 2.7 cm. Such
penetrations make it difficult for the nut peeling. European nuts are said to be easiest