research
Michigan State to have 20 different tion research. Within each green- can achieve various combinations standing of how the environment
climate-controlled greenhouse house, and even on individual of photoperiod, light intensity and infl uences crop timing and quality.
sections for fl oriculture produc- benches within a greenhouse, we temperature to further our under- We have determined the effects of
daily light integral (DLI) and pho-
toperiod on growth attributes (e.g.,
branching and stem thickness) and
fl owering characteristics (e.g., time
to fl ower and fl ower number) of a
wide range of bedding, potted and
EDUCATION
perennial ornamental crops. That
research continues today as the
MERCHANDISING SHOWCASE
need for effi cient crops and reli-
able scheduling increases.
IDEA EXCHANGES
WORKSHOPS DLI Research
SEMINARS
The DLI available to green-
house crops varies considerably,
TOURS depending on the time of year,
location, cloud cover, crop spacing,
glazing material, overhead obstruc-
2010
tions, and use of supplemental
lighting, whitewash and shade
curtains. A recent focus of our
research has been to quantify how
the average DLI infl uences root and
At the Heart
shoot growth of cuttings and seed-
lings as well as crops after trans-
plant into their fi nal containers.
of it All
Many bedding and peren-
nial crops are propagated from
December through March, when
the day length is short and the angle
of the sun is relatively low. During
this time, the DLI is low, especially
in the northern half of the United
States and in Canada. We have
TRADE shown that a low DLI during prop-
SHOW
agation can inhibit rooting of cut-
tings and seedlings. For example,
cuttings of petunia rooted under a
very low DLI took longer to become
established compared with a higher
MEET SUPPLIERS
DLI (Figure 2, page 29). Therefore,
during the darkest periods of the
SEE NEW PRODUCTS
year (December and January),
ONE-STOP
AND NEW VARIETIES
supplemental lighting from high-
SHOPPING pressure sodium (HPS) lamps can
shorten liner production time.
Many Northern propagators of
NETWORKING
young plants have HPS lighting in
only a part of their greenhouses.
Greenhouse growers asked when
lighting would have the big-
SHARE IDEAS
gest impact if they could provide
AND SOLUTIONS
lighting during only a portion of
the plug stage.
In our research, we provided HPS
MEET FRIENDS BUILD RELATIONSHIPS
lighting during different seedling
AND COLLEAGUES
stages; in general, lighting had the
most benefi t when the natural DLI
The Heart of Horticulture
TM
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