important for freshly harvested seeds, which have more pronounced dormancy. An even longer extended cold treatment,
up to 28 days, maybe necessary for certain natural accessions to
break dormancy. Cold treatment of dry seeds is usually not
effective in breaking dormancy.
23. Some Arabidopsis natural accessions require a period of cold
(vernalization) to initiate flowering (e.g., Galdo-1, Monte-1,
Cit-0, Dog-4, Istisu-1, Valsi-1, Mir-0, Tamm-2). Young
rosettes (2–4 weeks old) of late flowering accessions should
be placed at 4
C for 4–7 weeks to accelerate flowering.
24. Various light sources can be used for optimal plant growth,
such as cool-white fluorescent bulbs, incandescent bulbs, very
high output (VHO) lamps, high-intensity discharge (HID)
lamps and shaded sun light. Cool-white fluorescent bulbs,
supplemented by incandescent lighting, are recommended in
growth chambers or growth rooms. HID lamps of 400–1000
watts are conventional in greenhouses in temperate climates to
supplement the sunlight or prolong the natural photoperiod.
25. Arabidopsis is a facultative long-day plant. Plants flower rapidly
under continuous light or long day (>12 h) photoperiods,
while under short days (<12 h) flowering is delayed, favoring
vegetative growth. Plants grow well under a cycle of 16 h
light/8 h dark, or under continuous light.
26. The temperature range for Arabidopsis growth is 16–25
C.
Lower temperatures are permissible, but higher temperatures
are not recommended, especially for germination through early
rosette development. Temperatures above 28
C are better
tolerated by more mature plants (past early rosette stage). In
general, high temperatures result in a reduced number of
leaves, flowers, and seeds. At lower temperatures, growth is
slow, favoring the vegetative phase, and flowering is delayed.
27. Greenhouses with satisfactory cooling, heating, and supplemental light are suitable for large-scale growth of lines that
do not require strict control of environmental conditions,
which include most Arabidopsis natural accessions as well as
species related to Arabidopsis. The use of a shade cloth during
the summer will help reduce light intensity and regulate temperature. However, conditions are often too hot in temperate
climates for Arabidopsis growth in greenhouses during the
summer. It may be necessary to provide supplemental evening
and morning light during the winter, since the plants generally
require a long photoperiod (at least 12 h) for flowering.
28. Most of the commercial growth chambers precisely control
light intensity, photoperiod, temperature (typically Æ1
C),
and often humidity. Custom plant growth rooms provide environmental control similar to that of reach-in chambers. Such
Handling Arabidopsis Plants
19
up to 28 days, maybe necessary for certain natural accessions to
break dormancy. Cold treatment of dry seeds is usually not
effective in breaking dormancy.
23. Some Arabidopsis natural accessions require a period of cold
(vernalization) to initiate flowering (e.g., Galdo-1, Monte-1,
Cit-0, Dog-4, Istisu-1, Valsi-1, Mir-0, Tamm-2). Young
rosettes (2–4 weeks old) of late flowering accessions should
be placed at 4
C for 4–7 weeks to accelerate flowering.
24. Various light sources can be used for optimal plant growth,
such as cool-white fluorescent bulbs, incandescent bulbs, very
high output (VHO) lamps, high-intensity discharge (HID)
lamps and shaded sun light. Cool-white fluorescent bulbs,
supplemented by incandescent lighting, are recommended in
growth chambers or growth rooms. HID lamps of 400–1000
watts are conventional in greenhouses in temperate climates to
supplement the sunlight or prolong the natural photoperiod.
25. Arabidopsis is a facultative long-day plant. Plants flower rapidly
under continuous light or long day (>12 h) photoperiods,
while under short days (<12 h) flowering is delayed, favoring
vegetative growth. Plants grow well under a cycle of 16 h
light/8 h dark, or under continuous light.
26. The temperature range for Arabidopsis growth is 16–25
C.
Lower temperatures are permissible, but higher temperatures
are not recommended, especially for germination through early
rosette development. Temperatures above 28
C are better
tolerated by more mature plants (past early rosette stage). In
general, high temperatures result in a reduced number of
leaves, flowers, and seeds. At lower temperatures, growth is
slow, favoring the vegetative phase, and flowering is delayed.
27. Greenhouses with satisfactory cooling, heating, and supplemental light are suitable for large-scale growth of lines that
do not require strict control of environmental conditions,
which include most Arabidopsis natural accessions as well as
species related to Arabidopsis. The use of a shade cloth during
the summer will help reduce light intensity and regulate temperature. However, conditions are often too hot in temperate
climates for Arabidopsis growth in greenhouses during the
summer. It may be necessary to provide supplemental evening
and morning light during the winter, since the plants generally
require a long photoperiod (at least 12 h) for flowering.
28. Most of the commercial growth chambers precisely control
light intensity, photoperiod, temperature (typically Æ1
C),
and often humidity. Custom plant growth rooms provide environmental control similar to that of reach-in chambers. Such
Handling Arabidopsis Plants
19