 |
The
wild ancestor of Malus domestica is Malus sieversii (which
has no common name), a tree still found wild in the mountains
of Central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan,
and Xinjiang, China. M. sieversii resists many diseases
and pests that affect domestic apples, and research with
it to develop new disease-resistant apples is continuing.
Other species that were previously thought to have made
contributions to the genome of the domestic apples are
Malus baccata and Malus sylvestris, but there is no hard
evidence for this in older apple cultivars. These and
other Malus species have been used in some recent breeding
programmes to develop apples suitable for growing in climates
unsuitable for M. domestica, mainly for increased cold
tolerance. |
|
|
Apples
have been a very important food in all cooler climates,
and is probably the earliest tree to be cultivated. To
a greater degree than other tree fruit, except possibly
citrus, apples store for months while still retaining
much of their nutritive value. Winter apples, picked in
late autumn and stored just above freezing, have been
an important food in Asia and Europe for millennia, and
the United States since the arrival of Europeans. There
are more than 7,500 known cultivars of apples. Different
cultivars are available for temperate and subtropical
climates. Apples do not flower in tropical climates because
they have a chilling requirement. Commercially-popular
apple cultivars are soft but crisp. |
|
