Cho, A.R.,
Song, S.J.,
Chung, S.W.
and Kim, Y.J. 2019.
"CO2 enrichment
with higher light level
improves flowering quality
of Phalaenopsis Queen
Beer 'Maneforn.'
Scientia Horticulturae
247: 356-361
SUMMARY:
Six hours of CO2
enrichment each day
over the 16-week period
was sufficient to stimulate
orchid photosynthesis
spiking rates, spike length,
production of floral buds
and lateral branches, and
plant water use efficiency.
In the high light regime,
the percentage of plants
that flowered
ranged from
zero at 400 ppm CO2,
zero at 400 ppm CO2,
to +67% at 800 ppm CO2, and
+100% at 1200 ppm CO2 !
Cho et al. conclude that
"CO2 enrichment combined
with high light of
260 ± 40 µmol m-2 s-1
promotes the flowering quality
of Phalaenopsis," adding that
"CO2 enrichment under
high light conditions
may provide a means
for producing high-quality
Phalaenopsis Queen
Beer 'Mantefon'."
Such findings are great news for
the commercial orchid market !
None of the orchid plants
produced flowers under
the low light regime.
DETAILS:
Cho et al. (2019) note that
"the greenhouse industry
has long recognized the value
of enhancing photosynthesis
by manipulating light and CO2
for improves success
in plant cultivation."
They also note that
"maximizing the photosynthetic
carbon fixation with optimal light level
and CO2 concentration is important
for optimal growth and flowering
in Phalaenopsis [orchids]."
They examined the influence of
atmospheric CO2 concentration
and light level -- on plant photosynthesis,
growth and flowering percentage
during the flowering stage
of the Queen Beer 'Mantefon' orchid.
The four South Korean researchers
subjected 20-month-old orchid plants
(entering the flower induction stage
of growth) to one of three different
atmospheric CO2 concentrations
( 400, 800 or 1200 ppm ) and
one of two light intensities
( 90 ± 10 or 260 ± 40 µmol m-2 s-1,
corresponding to low or high light levels,
respectively) over a period of 16 weeks.
Lighting treatments were applied
from 0600 to 1800 hours each day
and atmospheric CO2 treatment levels
were maintained during the hours
0000 to 0600 ( in the dark because
they perform crassulacean acid
metabolism -- CAM photosynthesis --
at night when their stomata are open ).
