Volume 30 Number 1 Article 8 Pages: 11-11
Year 1976 Month 1
Title: Greenhouse Forced Flowering as a Tool for Disease Resistancer
Authors: H.S. Aldwinckle and R.C. Lamb
Citation
Abstract:
Apple seedlings in two progenies
were screened for resistance to apple
scab (Venturia inuequdis) and then
grown in the greenhouse under optimum
conditions of light, temperature,
fertilization and pest control.
Without
any cold treatment certain plants began
flowering 16 months after germination.
Other plants flowered after
manual defoliation.
A second defoliation
initiated flowering in more plants
so that by 26 months after germination
93% of the surviving plants in one
nrogeny and 89% in the other had
flowered.
Some plants flowered three
times, at 6-8 month intervals, within
32 months of germination.
The original
force flowered plants were transplanted
to the field when 33 months
old.
They flowered the same year.
Crosses were made using the force
flowered plants as pollen and as seed
parents.
Cross-fertilization was confirmed
by using genes for scab resistance
as markers in test crosses with
susceptible cultivars.
In further research, seedlings have
been screened in their first year in
the greenhouse for resistance to apple
scab, cedar apple rust and fire blight.
Selected plants resistant to all three
diseases were then grown under optimum
conditions in the greenhouse.
At 18 months, many plants were at
least 3m high, the mean height at
which the lowest flower clusters developed
on plants of earlier progenies
flowering within 20 months of germination.
The force flowering technique is
useful in combining several major genes for scab resistance with resistance
to other diseases such as cedar
apple rust (Gymnosporangium juniperi-
virginianae), fire blight (Erwinia
amylovora), and powdery mildew
(Podosphuera leucotrichu) that can be
detected in young plants.
Rapid back
crossing to improve size and quality
can then be done.
Evaluation of fruit
and tree characters, however, must
still be made in the field.
APS membership administration
ISHS membership administration
