Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-90-22
Title: Effect of bottom heating regimes on growth of three foliage plants
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 Material Information
Title: Effect of bottom heating regimes on growth of three foliage plants
Series Title: CFREC-Apopka research report
Physical Description: 4 p. : ; 28 cm.
Language: English
Creator: Poole, R. T ( Richard Turk )
Conover, Charles Albert, 1934-
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, IFAS, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1990
Subject: Foliage plants -- Effect of temperature on -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 2).
Statement of Responsibility: R.T. Poole and C.A. Conover.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065856
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70288126

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Effect of Bottom Heating Regimes on Growth of Three Foliage Plants -; ,

R.T. Poole and C.A. Conover

University of Florida, IFAS F' 3 2
Central Florida Research and Education Center-Apopka
CFREC-Apopka Research Report, RH-90-22

Tropical foliage plants are among the most energy consuming of all
greenhouse crops to produce. Even in Florida, with its sub-tropical
climate, growers are looking for ways to reduce energy costs. One method
of energy conservation is utilization of bottom heat. In greenhouses where
bottom heat has been employed in the production of some flowering plants
and woody ornamentals, air temperature was reduced without increasing crop
turnover time because bottom heating elevated the root zone temperature.
This increased the rate of uptake of nutrients from the potting medium and
the resulting plant growth was comparable to plants grown in higher air
temperatures without bottom heat. Very little research has been conducted
on bottom heating regimes in foliage plant production or on the scheduling
of such bottom heat regimes. The following study was designed to examine
the growth of three species of foliage plants subjected to various air
temperatures and bottom heat regimes.

A 4 x 4 factorial experiment was initiated 20 December 1989, using
liners of Dieffenbachia maculata 'Camille' (Camille dieffenbachia),
Epipremnum aureum (golden pothos) and Spathiphyllum 'Petite' ('Petite' or
'Bennett' spathiphyllum) potted into 6-inch standard pots with Vergro
Container Mix (Canadian sphagnum peat moss, coarse vermiculite and perlite,
without superphosphate, Verlite Co., Tampa FL 33680). Pots were then
placed in zoned forced-air chambers where plants received (1) control, no
bottom heat, (2) 750F minimum bottom heat from 6 a.m. to 6 p.m. daily, (3)
750F minimum bottom heat from 6 p.m. to 6 a.m. nightly, or (4) 750F
constant minimum bottom heat. The forced-air chambers were located in
glasshouses receiving a maximum 1500 ft-c light and plants were subjected
to minimum air temperatures of 60, 65, 70 or 750 F. Plants received 5
grams/pot 19-6-12 Osmocote 3-month release rate fertilizer (Sierra Chemical
Co., Milpitas, CA 95035) at time of placement in glasshouses and were
irrigated 3 times per week.

Height or vine length was measured initially and monthly
thereafter. The number of hours bottom heaters and air heaters operated to
maintain the various minimum potting medium and air temperatures tested
were recorded daily. Air temperature at bench level and potting medium
temperature taken from pots growing golden pothos were recorded twice a
week at 8:00 a.m. and 1:00 p.m. from (1), the control, receiving no bottom
heating, for each of the four air temperatures tested. Plant grade, based
on a scale of 1 poor quality, unsalable, 3 fair quality, salable and 5
excellent quality plant material, was determined when experiment ended on
27 March 1990.

IProfessor of Plant Physiology and Professor and Center Director,
respectively. Central Florida Research and Education Center, 2807 Binion
Road, Apopka, FL 32703.

Increasing air temperature from 600F to 75F increased growth and
plant grade of Camille dieffenbachia and golden pothos, but had no effect
on Petite spathiphyllum (Table 1). Neither the presence or absence of
bottom heat, nor the hours regimes were implemented affected growth and
quality of Petite spathiphyllum. Best quality golden pothos were produced
from the control group which received no bottom heating. Plant grades were
slightly higher for Camille dieffenbachia when plants received 750F minimum
bottom heat for 12 hours during the day, from 6 a.m. until 6 p.m., but the
increase in plant quality was too small to justify the extra expenditure.
Results from this experiment show the bottom heating schedules used in the
production of the three species tested; 1, had no affect on Petite
spathiphyllum, 2, 12 hours during the daytime slightly increased plant
quality but was not cost effective for Camille dieffenbachia, and 3,
actually proved detrimental to growth of golden pothos.

Hours air heaters were in operation almost doubled when minimum air
temperature was maintained at 750F as opposed to 700F and about a 10 fold
increase in hours of operation was needed to maintain 750F instead of 60F
(Table 2). When minimum air temperature maintained was 700F potting media
temperatures recorded at 8:00 am. and 1:00 pm. were never more than 6F
lower than air temperatures recorded at the same time (Table 3). Since
there was only a slight increase in plant growth and grade for all species
tested when air temperature was increased from 700F to 750F, we recommend
utilizing the 700F air temperature for these plants if energy conservation
is a priority.

Additional Reading

1. Bodnaruk, W. H., Jr., T. W. Mills, and D. L. Ingram. 1981.
Response of four foliage plants to heated soil and reduced air
temperatures. Proc. Fla. State Hort. Soc. 94:104-107.
2. Conover, C. A. and R. T. Poole. 1987. Growth of Dieffenbachia
maculata 'Perfection' as affected by air and soil temperatures and
fertilization. HortScience 22(5):893-895.
3. Jones, W. H. and R. McAvoy. 1982. Effect of root zone heating on
growth of Poinsettia. J. Amer. Soc. Hort. Sci. 107:525-530.
4. Koller, D. C., L. K. Hiller, and R. W. Van Denburgh. 1980. A forced-
air system for controlling soil temperatures in plastic pots.
HortScience 15:189-190.
5. Wang, Y. T. and A. N. Roberts. 1983. Influence of air and soil
temperatures on the growth and development of Lilium longiflorum Thumb.
during different growth phases. J. Amer. Soc. Hort. Sci. 108:810-815.
6. White, J. W. and J. A. Biernbaum. 1984. Effects of root-zone heating
on growth and flowering of calceolaria. HortScience 19:289-290.

Table 1. Growth and plant
20 December 1989

grade of three foliage plants grown from
through 27 March 1990 utilizing various air

temperatures and bottom heating regimes.
Dieffenbachia maculata Epipremnum aureum Spathiphyllum
'Camille' 'Petite'

Air Temp Plant Plant Plant
(F) Height Grade Height Grade Height Grade

60 27.5 2.9 23.7 4.3 22.1 2.4
65 31.3 3.4 27.3 4.4 23.8 2.7
70 31.0 3.8 30.3 4.7 22.9 2.6
75 32.8 3.8 30.1 4.8 23.9 2.6

linear ** ** ** ** ns ns
quadratic ns ns ns ns ns ns
cubic ns ns ns ns ns ns

Bottom heating

Control 30.6ax 3.5ab 32.7b 4.5a 23.8a 2.6a
750F 6a.m.-6p.m. 30.9a 3.7b 29.2b 4.7a 23.2a 2.8a
750F 6p.m.-6a.m. 30.9a 3.5ab 24.7a 4.6a 23.1a 2.7a
750F constant 30.2a 3.2a 24.8ab 4.4a 22.5a 2.4a
"Plants were graded on a scale of 1 = poor quality, unsalable, 3 =
average quality, salable, and 5 = excellent quality.
Yns, **, Nonsignificant or significant at P = 0.01.
XMean separation in columns by Duncan's multiple range test, 5%.

Table 2. Number of hours air heaters were in operation to maintain
greenhouses at air temperatures tested from 1 January
through 26 March 1989.

Air temperature
(F) Jan Feb Mar Total hours

60 15 16 14 45
65 64 36 39 139
70 98 62 64 224
75 164 124 123 411

Table 3. Air and potting media temperatures recorded at
1:00 pm twice a week in greenhouses where test
grown from 4 January through 21 March 1989.

8:00 am and
plants were

JAN 16 JAN 16 FEB 05 FEB 05
8:00 AM 1:00 PM 8:00 AM 1:00 PM

Air Heater Air Media Air Media Air Media Air Media
Setting (OF) Temp Temp Temp Temp Temp Temp Temp Temp

60 60 61 83 73 61 62 80 72
65 66 66 82 75 68 66 81 75
70 70 70 84 78 71 69 83 79
75 76 72 83 79 76 72 82 80

FEB 27 FEB 27 MAR 19 MAR 19
8:00 AM 1:00 PM 8:00 AM 1:00 PM

Air Heater Air Media Air Media Air Media Air Media
Setting (OF) TempTempp Temp Temp Temp Temp Temp Temp

60 63 60 80 75 63 60 85 75
65 67 65 80 75 68 64 84 77
70 71 68 86 77 72 68 86 78
75 76 71 84 79 76 71 86 79

ZAir temperature data obtained from thermometers placed at bench level.
YMedia temperature readings obtained from thermometers placed in control
media, receiving no supplemental heat, in pots containing Epipremnum


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