Under Control - 2019 - 11

'Albion'
Ambient
HPS
'Cabrillo'
LED
Ambient
HPS
Strawberry plants grown under LED lights produced more berries so
the yields were larger and fruit size was larger.
almost always one to two crowns per plant. The plants
under ambient light never developed as many crowns as the
supplemental light treatments. The vegetative growth on the
ambient light plants was also much slower.
Under ambient light the plants had very little energy so the
total strawberry yield was much smaller. The ambient light
plants produced fewer berries and each berry was larger. LEDs
produced more berries so the yields were larger and had a
larger berry size.
In all cases for the five-month trial, the light treatments
outperformed the ambient light treatment for total yield.
Under ambient light, the yield for 'Albion' was 1.77 kilograms
per square meter. Under HPS lights, the yield was 2.72
kilograms per square meter. 'Albion' had its highest yield under
LEDs at 3.68 kilograms per square meter, which was 100% over
ambient light.
'Cabrillo' under ambient conditions had a yield of 3.03
kilograms per square meter. 'Cabrillo' had a 72% higher yield
than 'Albion' under ambient light. Under HPS, the yield for
'Cabrillo' was 4.9 kilograms per square meter. Under LEDs, the
yield for 'Cabrillo' was 5.67 kilograms.
Under ambient and LED light, the average berry size for
'Albion' was 16 grams per berry. Under HPS light, 'Albion'
berry size was 14 grams per berry.
'Cabrillo' followed the same berry size trend as 'Albion'.
Under ambient and LED light, the berry size for 'Cabrillo' was
18 grams. Under HPS light the berry size was 15 grams.
Under HPS lights, both cultivars produced the smallest
berries, but plants had more berry clusters. Allred said the
radiant heat provided by HPS lamps wasn't necessarily
beneficial because the berries were smaller and yields were
lower than LEDs. He couldn't say whether the differences in
yield and berry size were due to the temperature difference or if
the light quality may have played a role.
LED
For the five month trial done at Cornell University, HPS and LED
light treatments outperformed the ambient light treatment for total
strawberry yield of 'Albion' and Cabrillo'.
The sweetness of the fruit (Brix value, °Bx) was also measured
for the strawberries produced under the three different light
treatments. Under ambient light, 'Albion' had the lowest Brix
value at 7.4 degrees. Under LEDs, 'Albion' had a Brix of 8.5
degrees. 'Albion' strawberries grown under HPS had the highest
Brix at 9.4 degrees.
'Cabrillo' had slightly lower sugar content than 'Albion'. For
'Cabrillo,' grown with ambient light the Brix value was 5.9
degrees. Under LEDs, the Brix value was 6.7 degrees. As with
'Albion,' 'Cabrillo' grown with HPS lamps had the highest Brix
at 7.3 degrees.
FUTURE STRAWBERRY RESEARCH
Allred plans to run an identical trial with 'Albion' and
'Cabrillo' at the same time of year. Other experiments will be
conducted using a range of different DLIs, including 15, 20
and 25 moles per square meter per day.
" We are also going to be doing some other experiments
with light and carbon dioxide, looking at the interaction
between DLI and carbon dioxide, " he says. " One of the things
that can be done with greenhouse lettuce is a higher level
of carbon dioxide can be used to achieve the same yields as
higher light levels. For example, 1,000-ppm carbon dioxide
can offset the need for additional light by a couple moles of
light. We want to look at the impact of higher carbon dioxide
levels on strawberries. It may be possible to use higher carbon
dioxide levels to substitute for higher light levels in respect to
fruit yields. "
For more information: Contact Jonathan Allred at jaa337@
cornell.edu, or visit www.cornellcea.com, www.greenhouse.
cornell.edu or www.glase.org. v
David Kuack is a freelance technical writer in Fort Worth,
Texas. He can be reached at dkuack@gmail.com.
UNDER CONTROL: TIPS FOR CONTROLLED ENVIRONMENT GROWING * 2019 11
http://www.cornellcea.com http://www.greenhouse http://www.cornell.edu http://www.glase.org
Under Control - 2019

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