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

118 S. Pereira-Lorenzo and A. M. Ramos-Cabrer
style (Botta et al., 1995; Valdiviesso, 1999) and some of them can produce fertile
pollen. This should be taken into account in controlled crosses.
3.2. Floral biology
Figure 5. Shape variation in chestnut cultivars.
Cross-pollination is essential for normal production (Breisch, 1995). In the old
orchard, a combination of 2 upto 20 cultivars is practised to ensure pollination. In
some orchards, cross-pollinations are achieved from wild trees surrounding the
grafted trees. In new orchards, longistaminate cultivars are commonly chosen as
pollinators. Some of them produce large nuts.
Chestnuts pollen is transported by the wind in Mediterranean areas, but the
contribution from insect pollinators becomes more important as humidity in the
environment increases (Breisch, 1995).
Liu and Zhou (1999) have related the abundance of male flowering with the
low productivity of Chinese cultivars. This could also be linked to the association
made by Breviglieri (1955) between male sterility (astaminate and brachystaminate)
and ‘marroni’ type cultivars. Although it is logical to think that an astaminate
or brachystaminate cultivar, which does not produce any pollen, reserved more
energy to produce a bigger nut. Astaminate cultivars are less frequent in Spain. A