review: co 2 enrichment in greenhouses. crop …wittwer, 1966). the positive effect on greenhouse...
TRANSCRIPT
Scientia Horticulturae, 33 (1987) 1-25 1 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
Review: C O 2 Enrichment in Greenhouses. Crop Responses
LEIV M. MORTENSEN
Department of Floriculture and Greenhouse Crops, Agricultural University of Norway, P.O. Box 13, N-1432, .4s-NLH (Norway)
(Accepted for publication 8 April 1987)
ABSTRACT
Mortensen, L.M., 1987. Review: C02 enrichment in greenhouses. Crop responses. Scientia Hor- tic., 33: 1-25.
The interest in C02 enrichment has risen and declined several times throughout this century. During the last few years the interest of C02 enrichment has strongly increased, mainly due to a better scientific understanding of how C02 affects plants and due to the introduction of non- polluting C02 sources.
C02 enrichment decreases the oxygen inhibition of photosynthesis and increases the net pho- tosynthesis in plants. This is the basis for increased growth rates caused by C02 at low as well as at high light levels. Elevated C02 concentrations also increase the optimal temperature for growth.
Pot plants, cut flowers, vegetables and forest plants show very positive effects from C02 enrich- ment by increased dry weight, plant height, number of leaves and lateral branching. Plant quality expressed by growth habit and number of flowers is often enhanced by C02 enrichment. The rooting of cuttings is often stimulated by high C02 levels.
The optimal C02 concentration for growth and yield seems to lie between 700 and 900 HI l- I, and this C02 level is generally recommended in greenhouses. C02 concentrations higher than 1000 HI I- i might cause growth reductions and leaf injuries, and certainly do increase the loss of C02 due to leakage from the greenhouse.
Continuous C02 enrichment during the light period seems to be superior to intermittent CO~ application. C02 enrichment during periods of ventilation of the greenhouse increases the yield of cucumber, while some other species seem to be less affected.
Air pollution in connection with the burning of hydrocarbons for C02 enrichment might cause visible or invisible injuries to plants. The safest source of C02 is pure liquid C02 from containers, which is recommended for general use for greenhouse crops.
Further research with the C02 factor should mainly be concentrated on how C02 enrichment affects the optimal levels of temperature and air humidity for plant growth and quality.
Keywords: CO2 enrichment; greenhouse; responses; review.
0304-4238/87/$03.50 © 1987 Elsevier Science Publishers B.V.
INTRODUCTION
It is almost 200 years since the positive effects of CO2 enrichment on plant growth were first observed (Saussure, 1804). From about 1900 to the early 1930's, extensive C02 research was carried out in different European countries (Brown and Escombe, 1902; Demoussy, 1903, 1904a,b; Fischer, 1912, 1919; LSbner, 1913; Winter, 1913; Berkowski, 1913, 1914; Werth, 1914; Gerlach, 1919, 1920; Lundeg~rdh, 1924; Owen et al., 1926; Thorsrud, 1926; Bolas and Hen- derson, 1928; Small and White, 1930; Bolas and Melville, 1935) and in the U.S.A. (Cummings and Jones, 1918). CO2 research up to 1924 has been reviewed by Lundeg~rdh (1924). Many of the results were of limited value because of poor experimental methods. However, the positive effects of CO2 enrichment found in many experiments were quite convincing. In spite of this, C02 enrichment of the greenhouse atmosphere was not practiced to any great extent until the late 1950's. The main reasons were probably the use of soil rich in organic matter, which is a major source of C02, and the negative effects of air pollutants associated with the burning of hydrocarbons for CO2 enrich- ment. A new interest in CO2 enrichment arose again in the 1960's. Practical application of C02 followed in the wake of active research on CO2 during this decade (Gaastra, 1959, 1966; Daunicht, 1961a,b,c, 1965, 1966; Goldsberry, 1961; Holley and Goldsberry, 1961; Berkel, 1962, 1964; Holley et al., 1962; Golds- berry and Holley, 1962; Winden, 1962; Wittwer and Robb, 1964; H~rdh, 1966; Wittwer, 1966). The positive effect on greenhouse crops were stated again and again. However, many growers did not find any significant increase in growth or yield. Often plant injuries occurred, causing economic loss. They were most probably due to air pollutants produced during the process of burning kerosene or propane ( C2H4, CO, SO2 and NOx), or to uncontrolled and damagingly high CO2 concentrations ( > 3000 H1 l-1). The large interest in C02 enrichment arising in the 1960's declined again due to these problems. During the 1970's, CO2 enrichment was used almost exclusively for lettuce in Scandinavia. From 1980 until today, the use of CO2 enrichment in Scandinavian countries has increased strongly. Today CO2 enrichment is used in about 75% of the green- house area in Norway. This might be for any or all of the following reasons ( Moe and Mortensen, 1986):
(1) less air pollution due to the introduction of kerosene with a low sulphur content ( < 100 mg l- 1 ) and less leakage of propane from improved equipment;
(2) increased use of bottled CO2 gas free from any pollutants; (3) better control of the CO2 concentration by the use of manual measuring
equipment (Dr~iger or Kitagawa gas detectors) or automatic devices using infrared gas analyzers;
(4) improved greenhouse construction giving gas-tight greenhouses and lower CO2 concentrations during the period of high CO2 utilization by the plants;
(5) reduction of natural C02 production in the greenhouses due to the intro- duction of inorganic growing media and the use of concrete floors;
(6) better knowledge of how plants respond to CO2 enrichment in various environmental conditions;
(7) increased competition within the greenhouse industry, which encour- ages interest in high-efficiency production methods.
This review summarizes the observations made on the effects of C02 enrich- ment on plants grown in greenhouses. Unfortunately, many of the observa- tions are reported in a very incomplete way. However, in order to include as many species as possible, these observations are also included. As a basis for understanding the C02 responses observed, the review starts with the physio- logical aspects of CO2 enrichment.
PHYSIOLOGICAL ASPECTS
The main constituent of plant dry matter is carbon, approximately 45% (Salisbury and Ross, 1969). The source of carbon is the CO2 gas in the air which is taken up by the plant through the stomata, and fixed and transformed in a series of processes which form the so-called Calvin-Benson cycle. The normal CO2 concentration in the air is about 335 gl 1-1. This concentration is too low for maximum photosynthesis. The main reason for this is the compe- tition between atmospheric CO2 and 02 to be fixed by the enzyme ribulose diphosphate carboxylase. The normal 02 concentration of 21% inhibits CO2 uptake by the plant and increases a light-dependent respiratory (photorespir- ation) loss of carbon (Forrester et al., 1966; Hesketh, 1967; Joliffe and Tre- gunna, 1968; Ehleringer, 1979; Johal and Chollett, 1980). By increasing the CO2 level to 900 H1 l - 1, this O2-inhibition of photosynthesis is almost elimi- nated due to the increased CO2/02 ratio (Jensen, 1977; Mortensen, 1983b; Mortensen and Moe, 1983b; Mortensen and Ulsaker, 1985). This effect of increasing the C02 concentration is just as important at low as at high light levels, and in both instances stimulates plant growth. Until recently it was a common opinion that CO2 enrichment was effective at high light levels only. The positive effect of C02 enrichment, irrespective of light conditions, is now well established. It has been shown that the percentage effect on relative growth rate is about the same over a range of light levels ( Mortensen and Moe, 1983c; Mortensen and Ulsaker, 1985). This also means that the light compensation point is lowered by increased CO2 concentration (Mortensen and Moe, 1983b,d). It has been shown for some species that CO2 enrichment might com- pensate for a 30% reduction in light intensity (Mortensen and Moe, 1983c; Mortensen and Ulsaker, 1985).
The O2-inhibition of photosynthesis increases with increasing temperature (Joliffe and Tregunna, 1968; Laing et al., 1974; Monson et al., 1982; Mortensen and Ulsaker, 1985). Therefore, the effect of CO2 enrichment will increase with increasing temperatures within a certain range. The optimum temperature for
photosynthesis will, as a consequence, increase in CO2-enriched air (Joliffe and Tregunna, 1968; Enoch and Hurd, 1977; Monson et al., 1982; Mortensen, 1983c). However, there is a need for more research before the advantage of this particular effect of CO2 can be fully utilized in practice. The temperature programs for different greenhouse crops have been developed mostly at normal C02 concentration. They should be re-assessed with CO2 enrichment. In prac- tice, the growers are often advised to increase the ventilation temperature by 2-4 °C when CO2 enrichment is used (Holley and Goldsberry, 1963; Holley et al., 1964; Kimball and Mitchell, 1979; Freeman, 1983; Mortensen, 1983c).
Rising the CO2 concentration reduces the transpiration of plants by 20-40% (Janes, 1970; Enoch and Hurd, 1979; Tolley and Strain, 1984; Rogers et al., 1984; Jones et al., 1985; Morison, 1985). Water consumption is thus signifi- cantly reduced by CO2 enrichment at the same time as photosynthesis is increased. Recent experiments with Begonia×hiemalis have shown that increasing the relative air humidity from 60 to 95% decreased transpiration by about 50% (L.M. Mortensen, unpublished results, 1986). C02 enrichment at 95% relative humidity again decreased transpiration and water uptake by about 30%. Giving the plants a low nutrient concentration (conductivity level 1.0 mS cm- ~ ) at high air humidity resulted in no effect of CO2 enrichment on growth, due to nutrient deficiency. At a medium nutrient concentration (2.0 mS cm-~), C02 enrichment increased the growth but stem elongation and chlorotic leaves reduced the plant quality. CO2 enrichment at a high nutrient concentration (4.0 mS cm -1) increased growth and the plant quality was enhanced (reduced stem elongation, green leaves). The same experiments showed that CO2 enrichment increased the water-use efficiency ( ml water con- sumed per g dry weight produced) by about 30%. All this might imply that the concentration of the nutrient solution supplied to the plants should be main- tained at a somewhat higher level in C02-enriched air, especially at high air humidities, in order to avoid nutrient deficiency. Decreased transpiration might also result in higher leaf temperature due to less evaporative cooling, especially at high irradiation.
OPTIMAL C02 CONCENTRATION
At one time it was a common practice to enrich greenhouses to 2000-3000 H1 l- 1 CO2 because it was believed that the higher the concentration the better. Later, a CO2 concentration of 1000-1500 H1 l-1 was recommended. In the last few years, it has been shown in a number of experiments that concentrations above 900 H11-1 very seldom give any beneficial effect (Calvert and Slack, 1975; Mortensen, 1983b, 1986a; Mortensen and Moe, 1983a,c,d; Heij and Uff- elen, 1984; Mortensen and Ulsaker, 1985 ). For most species it is impossible to give the exact optimal CO2 concentration, because most experiments with CO2 enrichment only include a few CO2 concentrations (for example 335, 900 and
1500/11 l - 1 ). However, from the literature it might be concluded that the opti- mal C02 concentration for plant growth lies between 600 and 900 ~11-1 for most species. In Scandinavia, the recommended C02 concentration is 700-900 pl l-1 for most species. In some cases plant injuries have been observed at concentrations above 1000 pl 1-1, which is also an additional reason to keep the concentration no higher than 900 #11-1. Increased CO2 concentration will also increase the CO2 loss due to leakage from the greenhouse.
EFFECTS OF C02 ENRICHMENT ON DIFFERENT SPECIES
The effects of C02 enrichment on a range of plants grown in greenhouses are summarized in Tables I-IV. Pot plants, cut flowers, vegetables and some forest plants show very positive effects of CO2 enrichment by increased dry weight, plant height, number of leaves and lateral branching. Plant quality, expressed by growth habit and number of flowers, is also often enhanced by CO2 enrichment. More compact pot plants and thicker stems of cut flowers are often observed. Increased growth rates by CO2 application has in many cases reduced the production time. This means increased production per year. All this information clearly shows the great advantage of C02 enrichment to greenhouse plants in general. Unfortunately, much of the published literature on CO2 enrichment does not include the weight of the plants, time to flowering and number of flowers and flower buds. Also the environmental conditions are often poorly defined. This might be explained by the fact that the experiments were often designed to convince the growers about the benefits of C02. Visu- ally, the impact of C02 was convincing, but often the experiments were not followed up by sufficient measurements.
In many species, C02-enrichment stimulates root development of cuttings and on some it stimulates the subsequent growth (Table V). In some cases CO2 treatment of the stock plants has beneficial after-effects on the rooting of the cuttings and on their subsequent growth. Application of CO2 through car- bonated mist enhances rooting of cuttings due to CO2 enrichment of the air (Table V ). The positive effect of C02 enrichment on the rooting of cuttings is most probably due to increased concentrations of carbohydrates which enhance rooting (Mortimer, 1959; Madsen, 1968; Haaland, 1976; Moe, 1977).
INJURIES CAUSED BY HIGH C02 CONCENTRATIONS
Visible leaf injuries are sometimes observed in connection with C02 enrich- ment. These include chlorosis, necrosis and curling of the leaves. In controlled experiments, growth reductions have been observed at high CO2 concentra- tions without visible injuries. In Table VI, species which have been observed to respond negatively to CO2 enrichment, with or without visible injuries, are
TA
BL
EI
Eff
ect o
f C
02 e
nri
chm
ent
(100
0-15
00 #
l I
1 ) o
n g
row
th a
nd
flo
wer
ing
of g
reen
hous
e sp
ecie
s. S
ymbo
ls:
- =
no
t re
cord
ed;
0 =
no e
ffec
t; +
= 1
0-20
%;
+ +
= 20
-30%
, +
+ +
= 30
-50%
; an
d +
+ +
+ >
50%
inc
reas
e of
fre
sh o
r dr
y w
eigh
t, n
um
ber
of
leav
es,
nu
mb
er o
f la
tera
l b
reak
s an
d n
um
ber
of
flow
ers
as a
ffec
ted
by C
02.
Th
e in
crea
se i
n h
eig
ht
is g
iven
in
cm.
Th
e ef
fect
on
tim
e to
flo
wer
ing
is g
iven
as
foll
ows:
0 =
no
effe
ct;
+ =
1-5;
+
+ =
5-1
0;
+ +
+ =
10-1
5; a
nd
+ +
+ +
= 1
5-20
day
s ea
rlie
r fl
ower
ing
by
C02
en
rich
men
t. P
=p
ot
plan
ts;
S=
cut
flow
ers;
U=
bed
din
g p
lant
s;
*=
pro
duct
ion
of c
utti
ngs
from
sto
ck p
lant
s. S
ee f
ootn
ote
for
refe
renc
es
Pla
nt
spec
ies
Ty
pe
Wei
ght
Nu
mb
er
Nu
mb
er o
f H
eig
ht
Nu
mb
er o
f T
ime
to
Co
mm
ents
of
lea
ves
late
ral
(cm
) fl
ower
s fl
ower
ing
bre
aks
A ls
troe
mer
ia
Ant
huri
um s
cher
zeri
anum
A
phel
andr
a sq
uarr
osa
Beg
onia
× h
iem
alis
B
egon
ia ×
tube
rhyb
rida
B
runf
elsi
a ca
lyci
na
CaU
iste
phus
chi
nens
is
Cam
panu
la is
ophy
Ua
Chr
ysan
them
um f
rute
scen
s C
hrys
anth
emum
× m
orifo
lium
D
iant
hus
Dip
lade
nia
Eup
horb
ia p
ulch
erri
ma
Fre
esia
F
uchs
ia
Ger
bera
Hib
iscu
s
S --
--
P +
+
- P
- +
P +
++
+
U
++
+
- P
- _
P +
++
-
P +
++
-
V
--
--
SP
+
++
(+
) S
++
-
P -
_
P +
+(+
) +
S --
--
U
++
+
- S
+
P +
+
-
_ _
+(
+)
-
--
0 --
+
++
+
+
1.5
++
+
--
--
0 +
+(+
) +
+*
0
++
+
--
--
+
++
(+)
--
_ _
-
_ +
+
++
*
5 --
--
--
5-
10
+
+ --
++
*
0 +
0
(+)
_ _
+ +
+
++
+
3-9
+
++
+
(0)+
_
_ _
++
(+)
++
--
_
_
--
0-1
0
0+
-
+ 0
0 0
En
han
ced
flo
wer
qua
lity
(1)
S
pat
ha
+0
.4 c
m (
2)
Mo
re c
om
pac
t (3
) R
educ
ed l
eaf
size
(4)
(5
) (6
) In
crea
sed
flo
wer
wei
ght
(7)
(8)
Incr
ease
d g
row
th (
9)
(10)
B
ette
r qu
alit
y, m
ore
late
ral
bre
aks
(11)
B
ette
r g
row
th a
nd
lea
f co
lour
, ea
rlie
r an
d b
ette
r fl
ower
ing
(12)
D
iam
eter
of
star
+ 0
-2 c
m (
13)
En
han
ced
qua
lity
(14
) (1
5)
Eff
ect
dep
end
ing
on
cult
ivar
; fl
ower
di
am.
+0
.5 c
m (
16)
Ear
lier
flo
wer
s an
d m
ore
flow
ers
(17)
Imp
ati
ens
rep
ens
U
+ +
+ +
- +
+ +
+ 1-
2 K
ala
nch
oe
blo
ssfe
ldia
na
p
+
÷
÷
- +
+
1
Lil
ium
S
+
+
( +
)
- -
-
i m
B
Pa
chys
tach
ys
P
..
..
.
Pa
vio
na
m
ult
iflo
ra
U
+ +
+ ( +
)
- 4-
6 -
Pa
larg
on
ium
h
ort
oru
m
p +
+ ( +
)
- -
0-1
+ +
( + )
P
etu
nia
U
+
+
+
.
..
.
Ro
sa
S +
+(+
) 0
- 3-
5 +
+
Sa
intp
au
lia
io
na
nth
a
p +
+ +
+ +
+ ( +
)
- 1-
2 +
+ +
( + )
S
alv
ia
U
- 0
- -
-
Sin
nin
gia
p
..
..
0
Tag
etes
U
+ +
- -
0 -
Tulip
a S
0 0
0 0
0
- (1
8)
+ V
isua
lly:
mor
e fl
ower
s (1
9)
+ B
ette
r qu
alit
y, r
educ
ed f
low
er d
rop;
in
crea
sed
stem
sti
ffne
ss a
nd g
reen
co
lour
ing
of le
aves
(20
) 0
Cur
led
leav
es, r
educ
ed q
uali
ty (
21)
- L
arge
r le
aves
(22
) +
+(+
) (2
3)
÷+
(+)
(24)
( +
)
Red
uced
no.
of b
lind
sho
ots
(25)
+
÷+
(+)
(26)
0
Mor
e co
mpa
ct (
27)
0 In
crea
sed
grow
th, d
ark-
gree
n le
aves
(2
8)
0 Fl
ower
dia
m.
+ 0-
1 cm
(29
) 0
(30)
Ref
eren
ces:
(1)
Ver
boom
and
van
Sta
aver
en,
1978
. (2
) K
loug
art,
197
8; S
chm
idt,
198
6. (
3) M
tinc
h an
d L
einf
elde
r, 1
968;
Klo
ugar
t, 1
978.
(4)
L
inde
man
n, 1
973;
Ano
n., 1
981;
Mor
tens
en a
nd U
lsak
er,
1985
; Sch
mid
t, 1
985.
(5)
Dju
rhuu
s, 1
984.
(6)
Klo
ugar
t, 1
978.
(7)
Hug
hes
and
Coc
kshu
ll,
1969
. (8
) M
oe,
1977
. (9
) P
apen
hage
n, 1
983.
(1
0) K
obel
, 19
65;
Rii
s L
avse
n, 1
967;
Lin
dstr
om,
1968
; N
elso
n an
d L
arso
n, 1
969;
Hug
hes
and
Coc
kshu
ll,
1971
a,b,
197
2; S
koye
and
Too
p, 1
973;
Eng
et
al.,
1983
; Mor
tens
en a
nd M
oe,
1983
a,c;
Mor
tens
en,
1986
b. (
11)
Gol
dsbe
rry,
196
1, 1
963;
H
olle
y an
d B
aker
, 19
63; B
jerg
g~rd
, 19
64; M
cKea
g, 1
965;
Hol
ley,
196
7. (
12)
Rii
s L
avse
n, 1
967;
Klo
ugar
t, 1
978.
(13
) W
alla
and
Kri
stof
fers
en,
1974
; M
orte
nsen
, 19
85a.
(14
) A
non.
, 19
80b;
van
Os,
198
3. (
15)
Pap
enha
gen,
198
3. (
16)
Ber
kel,
1982
, 198
3; T
sujt
a, 1
983.
(17
) K
loug
art,
197
8; S
axe
and
Chr
iste
nsen
, 19
85.
(18)
Rei
mhe
rr,
1984
. (1
9) R
iis
Lav
sen,
196
7; M
orte
nsen
, 19
83b;
Pap
enha
gen,
198
3; S
chm
idt
and
Lau
terb
ach,
198
5b.
(20)
M
asta
lerz
, 19
68; D
urie
ux,
1978
. (2
1) A
non.
, 19
80a.
(22
) R
eim
herr
, 19
84.
(23)
Pap
enha
gen,
198
3; A
uge
et a
l., 1
984.
(24
) D
auni
cht,
196
6; W
alla
an
d K
rist
offe
rsen
, 19
74.
(25)
Hol
ley
and
Gol
dsbe
rry,
196
1; G
olds
berr
y an
d H
olle
y, 1
962,
196
6; L
inds
trom
, 19
65;
Mat
tson
and
Wid
mer
, 19
71;
Zie
slin
et
al.,
1972
; Han
d an
d C
ocks
hull
, 19
75a,
b; T
hom
pson
and
Han
an,
1976
; Jen
sen,
198
0; M
orte
nsen
and
Moe
, 19
83d;
Hen
drik
s, 1
985.
(26
) M
tinc
h an
d L
einf
elde
r, 1
967;
Sch
icke
danz
and
Gom
mli
ch,
1968
; M
orte
nsen
, 19
83e;
Aug
e et
al.,
198
4. (
27)
Wal
la a
nd K
rist
offe
rsen
, 19
74.
(28)
G
Stz,
198
5. (
29)
Wal
la a
nd K
rist
offe
rsen
, 19
74.
(30)
R. M
oe, p
erso
nal
com
mun
icat
ion,
198
6.
TA
BL
E
II
Eff
ect
of C
O2
enri
chm
ent
(10
00
-15
00
/zl
l- 1
) o
n f
olia
ge p
ot
pla
nts
. S
ym
bo
ls a
s in
Tab
le I
. In
so
me
case
s in
crea
se o
f h
eig
ht
is g
iven
as
a p
erce
nta
ge.
See
fo
otn
ote
for
ref
eren
ces
0o
Sp
ecie
s W
eig
ht
Nu
mb
er
of
Nu
mb
er o
f H
eig
ht
Co
mm
ents
le
aves
la
tera
l (c
m)
bre
aks
Asp
len
ium
+
+ (
+ )
- -
5 (1
) B
ou
vard
ia
..
..
B
ette
r g
row
th a
nd
qu
alit
y (
2)
Ch
loro
ph
ytu
m
..
..
L
arg
er p
lan
ts (
3)
Cis
s~
an
tart
ica
+
+ +
( +
) +
+ +
- 2
0-3
0
(4)
Cis
sus
rho
mb
ifo
lia
-
- +
+ 2
Pro
du
ctio
n t
ime
red
uce
d 1
0%
(5)
Co
dia
eum
+
+ -
- 17
%
Bet
ter
leaf
co
lou
r an
d p
lan
t m
orp
ho
gen
esis
, la
rger
lea
ves
(6
) C
offe
a a
rab
ica
-
+ +
-
- ( 7
) D
ieff
enb
ach
ia m
acu
lata
+
0
+ ÷
0
(8)
Ep
ipre
mn
um
a
ure
um
-
- -
17%
B
ette
r g
row
th (
9)
Eu
ph
orb
ia m
ilii
+
+ -
- 0
(10)
E
up
ho
rbia
tri
go
na
+
+ +
- -
2-
3 C
AM
-pla
nt,
+
CO
2 d
ay a
nd
nig
ht
(11)
F
ats
hed
era
liz
ei
+ +
+ +
- -
20
-30
(1
2)
Fa
tsia
jap
on
ica
-
- -
20
-30
%
Lar
ger
lea
ves
(13
) F
icu
s b
enja
min
a
+ +
+ +
+ -
4-
8 (1
4)
Fic
us
ela
stic
a
+ (
+ )
- -
- L
arg
er l
eav
es (
15)
Hed
era
hel
ix
+ +
( +
) +
( +
) -
5-1
5
(16)
M
on
ster
a d
elic
iosa
.
..
.
Du
rin
g w
inte
r sa
le v
alu
e in
crea
sed
27
%,
du
rin
g
sum
mer
no
eff
ect
(17)
N
eph
role
pis
exa
lta
ta
+ +
+
( +
)
- -
(18)
P
ach
ypo
diu
m l
am
erei
+
+ +
+ +
- 3
- 5
(19)
P
hil
od
end
ron
co
rco
vad
ense
+
+ +
- -
- (2
0)
Sch
effi
era
act
ino
ph
ylla
+
+ +
( +
) +
( +
) -
5 (2
1)
Sci
nd
ap
sus
au
reu
s .
..
.
Du
rin
g w
inte
r sa
le v
alu
e in
crea
sed
41
%,
du
rin
g
sum
mer
no
eff
ect
(22
) S
ole
iro
lia
sol
eiro
lii
+ +
+ -
- -
(23
) S
pa
thip
hyl
lum
h
ybri
da
-
- -
25%
B
ette
r g
row
th a
nd
qu
alit
y,
earl
ier
flo
wer
ing
S
tere
osp
errn
um
ch
elo
no
ides
20
%
(24)
S
yng
on
iurn
po
do
ph
yUu
m
+ +
+ -
- 5
-10
B
ette
r g
row
th a
nd
qu
alit
y (
25
) (2
6)
References: (I) Pa
penh
agen
, 1983; Au
ge et al., 19
84. (2) Pa
penh
agen
, 1983. (3) Pa
penh
agen
, 1983. (4) Reimherr,
1985a. (5) Anon., 1980a. (6) Riis
Lavsen, 1967; Klougart, 1978. (7) Pa
penh
agen
, 1983. (8) Klougart, 1978; Sa
xe and
Christensen, 1985. (9) Sc
hmid
t an
d Brundert, 1984. (1
0) Sch
midt
an
d Lauterbach, 1985a. (11
) Sc
hmid
t an
d Lauterbach, 1985a. (12
) Pa
penh
agen
, 1983. (1
3) Pap
enha
gen,
1983. (14
) Pa
penh
agen
, 1983; A
uge et al., 1984;
Saxe
and
Christensen, 1985; Reimherr,
1985
b. (15
) Ri
is Lavsen, 1967; Klougart, 1978. (16
) Ri
is Lavsen, 1967; Daugaard, 1
981; Sax
e an
d Christensen,
1985; Mortensen, 1
985b
. (1
7) Klougart, 1978. (18
) Mo
rten
sen,
1983e; Pa
penh
agen
, 1983; Sa
xe and
Christensen, 1985. (1
9) Sch
midt
and
Lauterbach,
1985a,b. (20
) Sc
hmid
t an
d Brundert, 1984. (21) Reimherr, 1985a. (22) Klougart, 1978. (23) Mo
rten
sen,
1985b. (2
4) Sch
midt
and
Brundert, 1984. (25)
Schm
idt an
d Brundert, 1984. (26) Sch
midt
and
Brundert, 1984.
9
TABLE III
The effect of C02 enrichment on vegetable plants. Symbols as described in Table I. See footnote for references
Plant species Plant dry or Yield Comments fresh weight
Brassica oleracea gongylodes + ÷ + + Capsicum a n n u u m - + + ( + ) Cucumis melo - + + ( + ) Cucumis sat ivus + + + ( + ) + + ( + ) Lactuca sativa + + + -
Lycopersicon escu len tum + + + ( + ) + + ( + )
So lanum melongena - + + ÷ +
Reduced production time (1) More and heavier fruits (2) Earlier flowering, more fruits ( 3 ) More and heavier fruits (4) Reduced production time by 15-25%. More and broader leaves (5) One week earlier flowering, less abortion under poor light condition, more and heavier fruits (6) Earlier flowering, more and larger fruits (7)
References: (1) Daunicht, 1961c. (2) Milhet and Costes, 1975; Uffelen, 1975; Enoch et al., 1976; Vijverberg and Uffelen, 1977. (3) Milhet and Costes, 1975. (4) Daunicht, 1961b; Slobbe, 1964; Enoch et al., 1970, 1976; Berkel and Uffelen, 1975; Dennis, 1980; Heij and Uffelen, 1984; Slack and Hand, 1985. (5) Wittwer and Robb, 1964; Enoch et al., 1970; Guttormsen and Moe, 1979; Hand et al., 1981; Mortensen, 1985b,c. (6) Wittwer, 1966; Hurd, 1968; Hand and Postlethwaite, 1971; Madsen, 1973; Canham, 1974; Calvert and Slack, 1975; Hicklenton and Jolliffe, 1978; Kim- ball and Mitchell, 1979. (7) Milhet and Costes, 1975.
listed. Based on the literature referred to in Table VI, the injurious effects of high concentrations may be explained by:
(1) too high leaf temperatures at high irradiance levels as affected by reduced transpiration at high C02 concentrations (this seems to take place especially after periods of dull weather);
(2) accumulation of starch which breaks down the chlorophyll, promoted by high light level and low temperatures;
(3) reduced nutrient uptake because of reduced transpiration, particularly at high air humidity.
In many cases, however, it might be difficult to give any good explanation. This is one of the areas where more research is needed.
TIME OF C02 APPLICATION
In Scandinavia, a CO2 concentration of 700-900 H11-1 is generally recom- mended from sunrise until sunset as long as the greenhouse is not ventilated. During the winter, artificial lighting is used extensively due to low solar radia- tion. CO2 enrichment is used throughout the irradiation period. CO2 is supplied mostly during the winter because of the limited need for ventilation. During
10
TABLE IV
Effect of CO2 enrichment (1000/~11-1 ) on growth of seedlings of forest plants. Symbols described in Table I. See footnote for references
Species Plant dry Shoot Comments or fresh elongation weight (cm)
Ilex aquifolium - 0-25 Four of seven cultivars responded positively (1)
Liquidambar styraciflua + + - (2) Picea abies + ÷ ÷ 3-5 Root and shoot similarly affected (3) Picea glauca - 0 (4) Picea pungens + + + 5 (5) Picea si tchensis + + + + 4 (6) P inus contorta + + + + 4 (7) P inus nigra 0 0 ÷ 50% increase of weight, but not
significant (8) Pinus ponderosa + + + 0 (9) Pinus silvestris - 5-10 (10) Pinus taeda - - (11 ) Pseudotsuga rnenzlesii - 0 (12)
References: (1) Lin and Molnar, 1982. (2) Tolley and Strain, 1984. (3) HArdh, 1966; Hurd, 1968; Yeatman, 1970; Siren and Alden, 1972; Mortensen, 1983b. (4) Lin and Molnar, 1982. (5) Tinus, 1972. (6) Canham and McCavish, 1981. (7) Canham and McCavish, 1981. (8) Canham and McCavish, 1981. (9) Tinus, 1972. (10) Siren and Alden, 1972. (11) Tolley and Strain, 1984. (12) Lin and Molnar, 1982.
the rest of the year, CO2 application might be given in periods of cloudy weather with no ventilation. On sunny days, C02 might be supplied in the early morn- ing and in the evening, but the effect of this enrichment is expected to be of minor importance.
C02 ENRICHMENT DURING VENTILATION
In a greenhouse without ventilation and without C02 application, thecon- centration might fall to below 200/ll 1-1 (HoUey et al., 1962; Sebesta and Reiersen, 1981; Schapendonk and Gaastra, 1984; Slack and Hand, 1985 ). Even with ventilation the concentration might decrease significantly below the out- side concentration. Levels of 250-300 #l 1-1 have been reported (Slack and Hand,. 1985; Grimstad and Mortensen, 1986). Therefore the question has been raised of whether CO2 should also be supplied during periods of ventilation. Experiments with cucumber in England (Slack and Hand, 1985) and Norway (Mortensen, 1986a) have shown 3-7 kgm -2 (8-19%) increase in yield by such enrichment. In the English experiments, constant concentrations of 350, 400 and 450/~1 l - 1 were compared with ambient and the effect increased with
11
TABLE V
Effect of C02 enrichment (1000-2000 pl l - 1 ) on root development on cuttings, and on the cutting weight 2-5 weeks later. The after effect on plant weight 4 weeks later in non-enriched air is also given. M = C02 enrichment to the stock plants only, and the weight of the rooted cuttings were taken after 5-14 weeks. T = CO~ enrichment through carbonated mist, root development recorded after 2-8 weeks. See footnote for references
Plant species Effects on root % increase % increase Comments development of cutting of plant
weight weight
Begonia X argento-guttata Longer roots 10 0 (1) Begonia X tuberhybrida None - 0 M (2) Campanula isophylla More and longer roots - 15-30 M (3) Chamaecyparis Higher rooting percentage - - T (4) Chrysanthemum '6408' Higher rooting percentage, - - (5)
more roots per cutting Chrysanthemum '6408' Higher rooting percentage, - - T (6)
more roots Dianthu~ Increased rooting - - M, earlier and
better flowering (7)
Ficus pumila None 0 0 (8) Fuchsia magellanica Longer roots 28 0 (9) Hedera helix Increased rooting 30-60 (10) Hedera helix None - 0 M (11) Hemigraphis alternata Longer roots 11 0 ( 12 ) Ilex aquifolium Higher rooting percentage, - - T (13)
longer and more roots Ilex crenata None - - T (14) Jupinerus horizontalis Higher rooting percentage, - - T (15)
more and longer roots Jupinerus sabina Higher rooting percentage, - - T (16)
more and longer roots Jupinerus squamata None - - T (17) Magnolia sieboldii More and longer roots - - T (18) Magnolia soulaniana Higher rooting percentage, - - T (19)
more and longer roots Osmanthus heterophyllic None 0 0 ( 20 ) Pelargonium X hortorum Increased rooting 0 0 ( 21 ) Peperomia glabella More and longer roots 50 0 ( 22 ) Potentillafruticosa More and longer roots - - T (23) Potentilla fruticosa Higher rooting percentage, - - (24)
more and longer roots Pseudotsuga menziesii Higher rooting percentage, - - T (25)
more and longer roots Rhododendron Varying - - T, in one cultivar
enhanced rooting, in two no effect (26)
Taxus X media Higher rooting percentage, - - T (27) more and longer roots
Thuja occidentalis Higher rooting percentage, - - more and longer roots
Weigela 'Centennial' Higher rooting percentage, - - more roots
T (28)
(29)
References: (1) Davis and Potter, 1983. (2) Djurhuus, 1984. (3) Moe, 1977. (4) Lin and Molnar, 1980. (5) Molnar and Cumming, 1968. (6) Molnar and Cnmming, 1968. (7) Holley and Altstadt, 1966. (8) Davis and Potter, 1983. (9) Davis and Potter, 1983. (10) Daugaard, 1981. (11) Daugaard, 1981. (12) Davis and Potter, 1983. (13) Lin and Molnar, 1980. (14) Lin and Molnar, 1980. (15) Molnar and C,,mrning, 1968. (16) Lin and Molnar, 1980. (17) Lin and Molnar, 1980. (18) Lin and Molnar, 1980. (19) Lin and Molnar, 1980. (20) Davis and Potter, 1983. (21) Davis and Potter, 1983; Reuther and Forschner, 1983. (22) Davis and Potter, 1983. (23) Molnar and Cumming, 1968. (24) Molnar and Cumming, 1968. (25) Lin and Molnar, 1980. (26) Lin and Molnar, 1980. (27) Lin and Molnar, 1980. (28) Molnar and Cumming, 1968. (29) Molnar and Cumming, 1968.
12
TABLE VI
Plant species in which visible injuries or growth reduction have been observed at high C02-con- centrations. The C02 level at which the injuries have been observed is given. See footnote for references
Plant species Injury level Description (#11 -~)
Asplenium 1200-1500
Begonia×cheimantha 1000
Bouvardia 1500 Codiaeum 900 Coffea arabica 1500 Chlorophytum 1500 Chrysanthemum × morifolium 1000-1500 Cucumus sativus 1500 Euphorbia pulcherrima 800 Ficus benjamina 1500 Fuchsia 1500 Gerbera 1000 Lactuca sativa 1000
Lycopersicon esculentum 1000-1500
Phaseolus vulgaris 1400 Philodendron corcovadense 900 Stereospermum chelonoides 900
Syngonium podophyUum 900
Growth reduction, necrotic spots on leaves (I) Chlorotic leaves, increases with irradiance level (2) Slight leaf chlorosis (3) Poor leaf colour during summer (4) Leaf number and size reduced (5) Reduced leaf size (6) Leaf necrosis in some cultivars (7) Leaf chlorosis and necrosis (8) Leaf chlorosis and necrosis (9) Growth reduction (10) Growth reduction (11) Leaf chlorosis and necrosis (12) Marginal leaf necrosis in cv. 'Baccarat' (13) Curling of leaves, leaf chlorosis and necrosis (14) Chlorosis of primary leaves (15) Reduced growth during summer (16) Young leaves chlorotic during summer (17) Reduced growth during summer and winter (18)
References: (1) Papenhagen, 1983; Auge et al., 1984. (2) R. Moe, personal communication, 1986. (3) Papenhagen, 1983. (4) Riis Lavsen, 1967. (5) Papenhagen, 1983. (6) Papenhagen, 1983. (7) Woltz, 1969; Woltz and Engelhard, 1971; Walla and Kristoffersen, 1974. (8) Berkel, 1984. (9) Papenhagen, 1983. (10) Papenhagen, 1983. (11) Papenhagen, 1983. (12) Berkel, 1982, 1983, 1984; Papenhagen, 1983. (13) Mortensen, 1985c. (14) Madsen, 1968; Berkel and Heij, 1971; Ber- kel, 1984. (15) Ehret and JoUiffe, 1985a. (16) Schmidt and Brundert, 1984. (17) Schmidt and Brundert, 1984. (18) Schmidt and Brundert, 1984.
increased concentration. Instead of keeping the CO2 level constant, irrespec- tive of the rate of ventilation, a constant CO2 flow of about 3-4 kg per 1000 m -2 would probably be advantageous. In a greenhouse with tomatoes, it was found tha t at a low ventilation rate (relatively low solar radiat ion), the C02 concentration at a CO2 flow of 2.8 kg per 1000 m -2 was 400-450 #l 1-1 ( Grim- stad and Mortensen, 1986). At high ventilation (high solar radiat ion), the CO2 concentration was 300-320 #1 l - 1 at the same CO2 flow. This means tha t a relatively low CO2 flow is needed to obtain a high concentration with limited
13
ventilation, while quite a high C02 flow is needed at a high ventilation rate. The greenhouse computers give the possibility of reducing the C02 concentra- tion step-wise by increased opening of the ventilators. However, in green- houses without computers, a constant CO2 flow of 3-4 kg per 1000 m-2 h-1 or more might be recommended for cucumber irrespective of the ventilation rate. Recent results from a greenhouse nursery in Norway indicate that flow rates up to about 10 kg 1000 m -2 h-1 in periods of ventilation might be of econom- ical benefit (J. Fuglerud, personal communication, 1986 ).
Experiments with tomatoes in England (Drakes, 1985 ), Denmark ( Saxe et al., 1985) and Norway (Grimstad and Mortensen, 1986) gave contradictory results for enrichment during periods of ventilation. In Denmark and Norway, an insignificant effect on the yield was found, while in England a 3.2 kg per m -2 (14.5%) yield increase was found. Experiments with roses have shown no effects of C02 enrichment in ventilation periods with a C02 flow-rate of 3.0-3.5 kg 1000 m-2 h - 1 ( Mortensen, 1986a ). In these experiments, C02 was supplied through perforated tubes placed on the ground.
INTERMITTENT C02 APPLICATION
In plants grown continuously at high C02 concentrations, photosynthetic rate tends to decrease with time (Newton, 1965; Frydrych, 1976; Aoki and Yabuki, 1977; Imai, 1978; Imai and Murata, 1978; Clough and Peet, 1981; Mor- tensen, 1983d; Bruggink, 1984; Ehret and Jolliffe, 1985a,b; Peet, 1986; Peet et al., 1986 ). This is reflected in much smaller effects of CO2 enrichment on rel- ative growth rate in long-term experiments than would have been expected on the basis of short-term measurements of the effects of CO2 on photosynthesis rates (Mortensen, 1983e; Mortensen and Moe, 1983b,c,d; Mortensen and Ulsaker, 1985). After transferring the plants back to a normal C02 level, it has been shown with cotton that the plants recovered within 4-5 days (Sasek et al., 1985 ). The acclimatization of plants to high CO2 concentrations has been suggested as being caused by accumulation of starch, increased stomatal or internal resistance, reduced activity of ribulose diphosphate carboxylase or decreased regeneration of ribulase diphosphate (Frydrych, 1976; Aoki and Yabuki, 1977; Caemmerer and Farquhar, 1981; Azcou-Bieto, 1983; Kriede- mann and Wong, 1984; Sasek et al., 1985; DeLucia et al., 1986; Peet, 1986; Peet et al., 1986). The question has been raised whether intermittent CO2 applica- tion would reduce the negative effect of continuous high CO2 levels. If this were the case, the same effect could be obtained using smaller amounts of CO2. Experiments with chrysanthemum, Saintpaulia and soy beans, however, show that continuous CO2 enrichment is superior ( Clough and Peet, 1981; Morten- sen, 1986b). Studies on tomatoes have shown that the yield decreases when the daily enrichment period is reduced (Calvert and Slack, 1976). It might
14
thus be concluded that continuous enrichment should be applied whenever possible.
SOURCES OF C02 AND AIR POLLUTION
A few years ago, plant injuries were quite common in connection with CO2 enrichment. This was particularly the case when C02 was supplied by burning kerosene (Hanan, 1973; Ashenden et al., 1977; Hand, 1982, 1983; Mortensen, 1983a). Ethylene (C2H4) pollution due to incomplete combustion was often observed. Ethylene is a plant hormone which stimulates senescence of the plants, causing leaf chlorosis and abscission, and flower-drop. Ethylene has therefore caused substantial crop losses (Abeles, 1973; Mortensen, 1982, 1983a; Woltering, 1985). Although there are differences in sensitivity to ethylene between species, the concentration in the greenhouse environment should not exceed 0.01/zl l - 1. While new kerosene burners do not produce ethylene at all, burners which have been run for a long period produce substantial amounts (L.M. Mortensen, unpublished results, 1982). Proper maintenance of the burners is therefore of the utmost importance. Carbon monoxide (CO) is also produced by incomplete combustion and causes injuries similar to those caused by ethylene, but 3000-5000 times higher concentrations of CO must be present in order to give similar damage (Zimmerman et al., 1933; Burg and Burg, 1967; Mortensen, 1982). In practice, the CO concentration in greenhouses is 0-5 /zl l - 1 and seldom gives rise to any problems (Mortensen, 1983a). Until recently, kerosene also contained sulphur in concentrations which generated sufficient SO2 to cause damage. These two pollutants, ethylene and SO2, were probably the main reason why CO2 application was often discredited. Since the intro- duction of low-sulphur kerosene ( < 100 mg S l - 1 ), SO2 pollution has ceased to be a problem (Ashenden et al., 1977; Hand, 1982).
Although kerosene is the CO2 source which has caused most problems, other hydrocarbons, such as propane, might also give rise to pollution. Leakage of commercial propane has caused severe plant injuries in some greenhouse hold- ings in Scandinavia. The propane contains propylene, an active analogue of ethylene, as a major pollutant (Hand, 1971). Safety systems have been improved, however, and the chance of leakage with modern equipment is small. Care should nevertheless be taken to provide sufficient air to avoid incomplete combustion and consequent ethylene and CO pollution. Recently a cucumber crop was almost completely ruined by improper combustion of propane in a greenhouse in Norway. Natural gas from the North Sea is used in some coun- tries for CO2 production, but until now not in Scandinavia. This gas consists mainly of methane and is in itself much less harmful to plants than commercial propane (Hand, 1982). With this gas also, however, care should be taken to supply sufficient air for complete combustion ( Hanan, 1973 ).
In addition to ethylene, nitrogen oxides (NOx=NO+NO2) are the most
TABLE VII
Effects of NOx-poUution (0.8-1.0 pJ 1-1) on See footnote for references
15
different greenhouse plants grown for 20-150 days.
Plant species Effect Description
Chrysanthemum × morifolium None (1) Cucumis sativus None (2) Dieffenbachia maculata Negative Necrotic spots, reduced
growth (3) Ficus benjarnina Negative Reduced growth (4) Ficus elastica Negative Reduced growth (5) Hedera canariensis None (6) Hedera helix Varying Varying effect from none to
reduced growth (7) Hibiscus rosasinensis None (8) Kalanchoe blossfeldiana None (9) Lac tuca sativa None (10) Lycopersicon esculentum Negative Strong growth and yield
reduction, some cultivars necrotic spots (11)
Nephrolepis exaltata None ( 12 ) Rosa Negative Reduced growth, less flowering
shoots (13) Saintpaulia ionantha Negative Reduced growth and delayed
flowering (14)
References: (1) Mortensen, 1985b., (2) Mortensen, 1985b. (3) Saxe and Christensen, 1985. (4) Saxe and Christensen, 1985. (5) Saxe and Christensen, 1985. (6) Saxe and Christensen, 1985. (7) Saxe and Christensen, 1985; Mortensen, 1985b. (8) Saxe and Christensen, 1985. (9) Mor- tensen, 1985b. (10) Mortensen, 1985b. (11) Taylor and Eaton, 1966; Spierings, 1971; Capron and Mansfield, 1977; Mortensen, 1985b,c. (12) Saxe and Christensen, 1985; Mortensen, 1985b. (13) Mortensen, 1985b. (14) Mortensen, 1985b.
important pollutants from the burning of hydrocarbons. NOx is produced from the reaction between 02 and N2 in the air at high temperatures. In greenhouses, concentrat ions up to 1/zl l - 1 have been measured with kerosene as well as with propane burners (Capron and Mansfield, 1975; Hand, 1979; Saxe, 1981; Mor- tensen, 1983a). At a C02 concentrat ion of 1000 #1 l-1, the NOx concentrat ion is often about 0.5/~l l-1. Nitrogen oxide (NO) is normally predominant and makes up approximately 75% of the oxides ( Capron and Mansfield, 1975; Ash- enden et al., 1977; Haukeness et al., 1978). Some propane and kerosene burn- ers, however, seem to produce predominant ly NO2 (Ashenden et al., 1977; Anderson, 1978). The injurious effect of NO and NO2 seem to be similar (Hill and Bennett , 1970; Capron and Mansfield, 1976). The effects of NOx on a range of plant species are summarized in Table VII. Some plants are sensitive and others not. The injuries can be visible with leaf chlorosis and necrosis, or
16
invisible with growth-reduction only. It has been shown that nitrite can accu- mulate to toxic levels in plants exposed to NOx (Zeevaart, 1976; Yoneyama et al., 1979). Differences between species with respect to NOx-sensitivity might be due to differences in nitrite reductase activity and/or the rate of NOx absorption of plants (Matsumaru et al., 1979; Yoneyama et al., 1979). How- ever, injuries caused by NOx have also been observed in plants without accu- mulation of nitrite (Yoneyama et al., 1979). It has been suggested that iron- containing redox agents in the photosynthetic electron transport chain might be complexed by NO, leading to a reduction of photosynthesis (Hill and Ben- nett, 1970). Cultivars within a species have also shown differences in sensitiv- ity to NO~ (Anderson and Mansfield, 1979; Mortensen, 1985b,c). There is also evidence for a much greater sensitivity at low compared to high light levels ( Mortensen, 1986c).
Because of the danger of visible or invisible injuries caused by pollutants following the burning of hydrocarbons, pure liquid C02 in bottles or containers is now generally recommended for greenhouses in Scandinavia. It has been reported that bottles with liquid CO2 might also contain some ethylene ( Mor- ison and Gifford, 1984). Care should therefore be taken to ensure that the CO2 gas delivered is clean.
CONCLUSIONS
During this century, the interest in CO2 enrichment of greenhouse crops has risen and declined several times. The strong interest in recent years is primar- ily based on scientific understanding of plant responses to CO2 enrichment in different climatic conditions, and to the problems of air pollution. CO2 appli- cation today is very important for optimal growing conditions and affects both yield and economy. CO2 is particularly important during the winter and periods with poor light conditions. A CO2 concentration of 700-900 #l l - 1 might gen- erally be recommended. Above this level, growth or yield increases are rela- tively seldom observed, injurious effects of C02 might occur and C02 loss by leakage increase. However, in spite of recent increased scientific knowledge within the field of CO2 enrichment, there is still a need for more research. In particular, the effect of CO2 enrichment at different temperature and humidity levels ought to be studied. A better understanding of why injuries caused by high CO2 concentrations occur is also needed.
ACKNOWLEDGEMENTS
The author is grateful to Prof. E. Stromme for his critical examination of the manuscript. This work was supported by a grant from the National Agri- cultural Research Council of Norway.
17
REFERENCES
Abeles, F.B., 1973. Ethylene in Plant Biology. Academic Press, New York, London. Anderson, L., 1978. Gas-fired heaters cause crop damage. Grower, 89: 574-575. Anderson, L.S. and Mansfield, T.A., 1979. The effects of nitric oxide pollution on the growth of
tomato. Environ. Pollut., 20: 113-121. Anonymous, 1980a. Danish pot plants of top quality in all Europe. Gartner Tidende, 43:634-636
(in Danish). Anonymous, 1980b. Better quality and more lateral breaks with C02 to freesia. Gartneryrket, 70:
883-884 (in Norwegian). Anonymous, 1981. Good results with carbon dioxide to Elatior begonia. Gartner Tidende, 4:38-39
(in Danish). Aoki, M. and Yabuki, K., 1977. Studies on carbon dioxide enrichment for plant growth. VII.
Changes in the dry matter production and photosynthetic rate of cucumber during carbon dioxide enrichment. Agric. Meteorol., 18: 475-485.
Ashenden, T.W., Mansfield, T.A. and Harrison, R.M., 1977. Generation of air pollutants from kerosene combustion in commercial and domestic glasshouses. Environ. Pollut., 14: 93-100.
Auge, R., Vidalie, H., Laffaire, M. and Guerin, L., 1984. Influence du gaz carbonique sur la croiss- ance et le developpement des plantes en pots. Rev. Hortic., 244: 29-35.
Azcou-Bieto, J., 1983. Inhibition of photosynthesis by carbohydrate in wheat leaves. Plant Phys- iol., 73: 681-686.
Berkel, N. van, 1962. Proeven met C02. Groenten Fruit, 17: 1773, 1775. Berkel, N. van, 1964. General aspects of the application of carbon dioxide. Meded. Dir. Tuinbouw
(Neth.), 27: 378-384. Berkel, N. van, 1982. Leaf die-off in gerbera caused by C02 enrichment. XXIst International
Horticultural Congress, Hamburg, International Society for Horticultural Science (1982), Vol. II, Abstract No. 1655.
Berkel, N. van, 1983. C02 doseren bij Gerbera. Meer dan 800 ppm is schadelijk. Vakbl. Bloemis- terij, 25: 47-50.
Berkel, N. van, 1984. Injurious effects of high C02 concentrations on cucumber, tomato, chrysan- themum and gerbera. Acta Hortic., 162: 101-112.
Berkel, N. van and Heij, G., 1971. Damage to tomato plants by C02 enrichment. A.R. Glasshouse Crops Res. Exp. Stn., Naaldwijk, 1969: 48-51.
Berket, N. van and Uffelen, J.A.M. van, 1975. C02 nutrition of spring cucumber in The Nether- lands. Acta Hortic., 51: 213-224.
Berkowski, W., 1913. Beobachtungen tiber das Wachstum der Pflanzen in kohlensiiurereicher Luft. Gartenwelt, 17: 707-709.
Berkowski, W., 1914. Pflanzenwachstum in kohlensiiurereicher Luft. Gartenwelt, 18: 445-446. Bjergg~rd, A., 1964. Carbon dioxide enhances development. Gartner Tidende, 80:61-62 (in
Danish). Bolas, B.D. and Henderson, F.Y., 1928. The effect of increased atmospheric carbon dioxide on the
growth of plants. Ann. Bot. O.S., 42: 509-523. Bolas, B.D. and Melville, R., 1935. The effect on the tomato plant of carbon dioxide produced by
combustion. Ann. Appl. Biol., 22: 1-15. Brown, H.T. and Escombe, F., 1902. The influence of varying amounts of carbon dioxide in the
air on the photosynthetic process of leaves and on the mode of growth of plants. Proc. R. Soc. London, 70." 397-413.
Bruggink, G.T., 1984. Effects of CO2 concentration on growth and photosynthesis of young tomato and carnation plants. Acta Hortic., 162: 279.
Burg, J.N. and Burg, E.A., 1967. Molecular requirements for the biological activity of ethylene. Plant Physiol., 42: 144-152.
18
Caemmerer, S. von and Farquhar, G.D., 1981. Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves. Planta, 153: 376-387.
Calvert, A. and Slack, G., 1975. Effect of carbon dioxide enrichment on growth, development and yield of glasshouse tomatoes. I. Responses to controlled concentrations. J. Hortic. Sci., 50: 61-71.
Calvert, A. and Slack, G., 1976. Effect of carbon dioxide enrichment on growth, development and yield of glasshouse tomatoes. II. The duration of daily periods of enrichment. J. Hortic. Sci., 51: 401-409.
Canham, A.E., 1974. Some aspects of C02, air temperature and supplementary artificial light on the growth of young tomato plants. Acta Hortic., 39" 175-181.
Canham, A.E. and McCavish, M.J., 1981. Some effects of C02, daylength and nutrition on the growth of young forest tree plants. I. In the seedling stage. Forestry, 54: 169-182.
Capron, T.M. and Mansfield, T.A., 1975. Generation of nitrogen oxide pollutants during C02 enrichment of a glasshouse atmosphere. J. Hortic. Sci., 50: 233-238.
Capron, T.M. and Mansfield, T.A., 1976. Inhibition of net photosynthesis in tomato in air polluted with NO and NO2. J. Exp. Bot., 27: 1181-1186.
Capron, T.M. and Mansfield, T.A., 1977. Inhibition of growth in tomato by air polluted with nitrogen oxides. J. Exp. Bot., 28: 112-116.
Clough, J.M. and Peet, M.M., 1981. Effects of intermittent exposure to high atmospheric C02 vegetative growth in soybean. Physiol. Plant., 53: 565-569.
Cummings, M.B. and Jones, C.H., 1918. The aerial fertilization of plants with carbon dioxide. Vermont Agric. Exp. Stn. Bull., 211: 1-56.
Daugaard, H., 1981. CO2 to stock plants and cuttings of Hedera. Ugeskr. Jordbruk, 28:403-405 (in Danish).
Daunicht, H.J., 1961a. Untersuchungen zur Wirkung des Kohlendioxyd-Angebots auf den Ertrag von Treibgemiisen unter besonderes Beriicksichtigung der Hydrokultur. I. Versuche zur Ermit- tlung der Abhiingigkeit des Ertrages vonder C02-Konzentration. Gartenbauwissenschaft, 26: 96-107.
Daunicht, H.J., 1961b. Untersuchungen zur Wirkung des Kohlendioxyd-Angebots auf den Ertrag von Treibgemilsen unter besonderes Beriicksichtigung der Hydrokultur. II. Versuche zur C02- Versorgung bei Hydrokultur. Gurkenversuche. Gartenbauwissenschaft, 26: 109-132.
Daunicht, H.J., 1961c. Untersuchungen zur Wirkung des Kohlendioxyd-Angebots auf den Ertrag von Treibgemilsen unter besonderes Beriicksichtigung der Hydrokultur. III. Versuche zur C02- Versorgung von Hydrokultur. Kohlrabiversuche. Gartenbauwissenschaft, 26: 133-149.
Daunicht, H.J., 1965. C02-Diingung; Entwicklung, heutiger stand, eigene Versuchergebnisse. Acta Hortic., 2: 86-96.
Daunicht, H.J., 1966. Methods and results of experiments on the effects of C02 concentration on vegetable crops. Acta Hortic., 4: 116-125.
Davis, T.D. and Potter, J.R., 1983. High CO2 applied to cuttings: Effects on rooting and subse- quent growth in ornamental species. HortScience, 18: 194-196.
DeLucia, E.H., Sasek, T.W. and Strain, B.R., 1986. Photosynthetic inhibition after long-term exposure to elevated levels of atmospheric carbon dioxide. Photosynthesis Res., 7: 175-184.
Demoussy, E., 1903. Sur la v~g~tation dans des atmosphbres riches en acide carbonique. C. R. Seances Acad. Sci., 136: 325-328.
Demoussy, E., 1904a. Influence sur la v~g~tation de l'acide carbonique. C. R. Seances Acad. Sci., 138: 291-293.
Demoussy, E., 1904b. Sur la v~g~tation dans des atmospheres riches en acide carbonique. C. R. Seances Acad. Sci., Paris, 139: 883-885.
Dennis, D.J., 1980. Effects of carbon dioxide enrichment and temperature program on the growth and yield of glasshouse cucumber. Acta Hortic., 118: 205-220.
19
Djurhuus, R., 1984. The effect of C02, daylength and light on the production and subsequent growth of Begonia × tuberhybrida cuttings. Acta Hortic., 162: 65-74.
Drakes, G.D., 1985. Most return from all summer long. Grower, 17: 15-19. Durieux, A.J.B., 1978. C02 tegen knopval bij teelt 'Enchantement' met bijbelichting. Vakbl.
Bloemisterij, 17: 24-25. Ehleringer, J.R., 1979. Photosynthesis and photorespiration. Biochemistry, physiology, and eco-
logical implications. HortScience, 14: 217-222. Ehret, D.L. and Jolliffe, P.A., 1985a. Leaf injury to bean plants grown in carbon dioxide enriched
atmosphere. Can. J. Bot., 63: 2015-2020. Ehret, D.L. and Jolliffe, P.A., 1985b. Photosynthetic carbon dioxide exchange of bean plants
grown at elevated carbon dioxide concentrations. Can. J. Bot., 63: 2026-2030. Eng, R.Y.N., Tsujita, M.J., Grodzinski, B. and Dutton, R.G., 1983. Production of chrysanthemum
cuttings under supplementary lighting and C02 enrichment. HortScience, 18: 878-879. Enoch, H.Z. and Hurd, R.G., 1977. Effect of light intensity, carbon concentration, and leaf tem-
perature on gas exchange of spray carnation plants. J. Exp. Bot., 28: 84-95. Enoch, H.Z. and Hurd, R.G., 1979. The effect of elevated C02 concentrations in the atmosphere
on plant transpiration and water use efficiency. A. Study with potted carnation plants. Int. J. Biometeorol., 23: 343-351.
Enoch, H,Z., Rylski, I. and Samish, Y., 1970. C02 enrichment to cucumber, lettuce and sweet pepper plants grown in low plastic tunnels in a subtropical climate. Israel J. Agric. Res., 20: 63 -69.
Enoch, H.Z., Rylski, I. and Spigelman, M., 1976. C02 enrichment of strawberry and cucumber plants grown in unheated greenhouses in Israel. Scientia Hortic., 5: 33-41.
Fischer, H., 1912. PflanzenernRhrung mittels Kohlens~iure. Gartenflora, 61: 298-307,336. Fischer, H., 1919. Die Kohlenstoffern~ihrung der Kulturpflanzen. Gartenflora, 68: 165-168. Forrester, M.L., Krotkow, G. and Nelson, C.D., 1966. Effect of oxygen on photosynthesis, pho-
torespiration and respiration in detached leaves. I. Soybean. Plant Physiol., 41: 422-427. Freeman, R., 1983. Better crops through carbon dioxide injection. Grower Talks, 47: 42-48. Frydrych, J., 1976. Photosynthetic characteristics of cucumber seedlings grown under two levels
of carbon dioxide. Photosynthetica, 10: 335-338. Gaastra, P., 1959. Photosynthesis of crop plants as influenced by light, carbon dioxide, tempera-
ture and stomatal diffusion resistance. Meded. Landbouwhogesch., Wageningen, 59: 1-68. Gaastra, P., 1966. Some physiological aspects of C02 application in glasshouse culture. Acta Hor-
tic., 4: 111-116. Gerlach, M., 1919. Kohlens~iurediingung. Mitt. Dtsch. Landwirtschaftsgesellschaft, 34: 54-62,
77-82. Gerlach, M., 1920. Kohlens~iurediingung, Dtsch. Landwirtschaftsgesellschaft, 35: 370-371. Goldsberry, K.L., 1961, Effects of carbon dioxide on carnation growth. Colo. Flower Grower Assoc.
Bull., 138: 1-5. Goldsberry, K.L., 1963. Growth of carnation increase blocks with supplementary C02. Colo. Flower
Grower Assoc, Bull., 164: 1-2. Goldsberry, K.L. and HoUey, W.D., 1962. Carbon dioxide research on roses at Colorado State
University. Colo. Flower Grower Assoc. Bull., 151: 1-6. Goldsberry, K.L. and Holley, W.D., 1966. Six-year evaluation of environment on yield and quality
of greenhouse roses. Colo. Flower Grower Assoc. Bull., 191: 1-3. Grimstad, S. and Mortensen, L.M., 1986. C02 during ventilation to tomatoes-- preliminary results.
Gartneryrket, 5:108 (in Norwegian). G~tz, W., 1985. Vom wirtschaftlichen Nutzen der C02-Diingung. Dtsch. Gartenbau, 14: 716. Guttormsen, G. and Moe, R., 1979. Climatic effects during the raising period of crisp lettuce plants
on the growth after transplanting. Meld. Nor. Landbrukshoegsk., 58: 1-15 (in Norwegian ).
20
Haaland, E., 1976. The effect of light and CO2 on the carbohydrates in stock plants and cuttings of Campanula isophylla Moretti. Scientia Hortic., 5: 353-361.
Hanan, J.J., 1973. Ethylene pollution from combustion in greenhouses. HortScience, 8: 23-24. Hand, D.W., 1971. C02 from hydrocarbon fuels. A.D.A.S.Q. Rev., 1: 18-23. Hand, D.W., 1979. Injury to crops in glasshouse polluted with nitrogen oxids. A.D.A.S.Q. Rev.,
33: 134-143. Hand, D.W., 1982. CO2 enrichment, the benefits and problems. Sci. Hortic., 33: 14-43. Hand, D.W., 1983. On guard for air pollution. Grower, 100: 23-28. Hand, D.W. and Cockshull, K.E., 1975a. Roses. I: The effects of C02 enrichment on winter bloom
production. J. Hortic. Sci., 50: 183-192. Hand, D.W. and Cockshull, K.E., 1975b. The effects of CO2 concentration on the canopy photo-
synthesis and winter bloom production of the glasshouse rose 'Sonia' (Syn. 'Sweet promise'). Acta Hortic., 51: 243-252.
Hand, D.W. and Postlethwaite, J.D., 1971. The response to C02 enrichment of capillary-watered single-truss tomato at different plant densities and seasons. J. Hortic. Sci., 46: 461-470.
Hand, D.W., Slack, G. and Sweeney, D.G., 1981. Lettuce: crop responses to controlled levels of C02 enrichment. Rep. Glasshouse Crops ires. Inst., 1979: 58-59.
H~rdh, J.E., 1966. Trials with carbon dioxide, light and growth substances in forest tree plants. Acta For. Fenn., 81: 1-10.
Haukeness, M.O., Maginnes, E.A., Green, G.H. and Brooks, E.E., 1978. Using the heat and carbon dioxide from turbine exhaust gases for the production of greenhouse tomatoes. HortScience, 13: 292-293.
Heij, G. and Uffelen, J.A.M. van, 1984. Effects of COs concentration on growth of glasshouse cucumber. Acta Hortic., 162: 29-36.
Hendriks, L., 1985. COs-Dfingung yon Rosen. Dtsch. Gartenbau, 51/52: 2340-2342. Hesketh, J., 1967. Enhancement of photosynthetic COs assimilation in the absence of oxygen, as
dependent upon species and temperature. Planta (Berl.), 76: 371-374. Hicklenton, P.R. and JoUiffe, P.A., 1978. Effects of greenhouse COs enrichment on the yield and
photosynthetic physiology of tomato plants. Can. J. Plant Sci., 58: 801-817. Hill, A.C. and Bennett, J.H., 1970. Inhibition of apparent photosynthesis by nitrogen oxides.
Atmos. Environ., 4: 341-348. Holley, W.D., 1967. Response of carnation to three concentrations of COs - - second report. Colo.
Flower Grower Assoc. Bull., 201: 1-4. Holley, W.D. and Altstadt, R.A., 1966. Adding C02 to carnation stock plants improves perform-
ance of the cuttings. Colo. Flower Grower Assoc. Bull., 192: 2-3. Holley, W.D. and Baker, R., 1963. Carnation Production. W.M.C. Brown, IA, 142 pp. Holley, W.D. and Goldsberry, K.L., 1961. Carbon dioxide increases growth of greenhouse roses.
Colo. Flower Grower Assoc. Bull., 139: 1-3. Holley, W.D. and Goldsberry, K.L., 1963. COs and temperature recommendations. Colo. Flower
Grower Assoc. Bull., 164: 3. Holley, W.D., Korns, C.H. and Goldsherry, K.L., 1962. The use of carbon dioxide on carnations.
Colo. Flower Grower Assoc. Bull., 149: 1-4. Holley, W.D., Goldsberry, K.L. and Juengling, C., 1964. Effects of COs concentration and tem-
perature on carnation. Colo. Flower Grower Assoc. Bull., 174: 1-5. Hughes, A.P. and Cockshull, K.E., 1969. Effects of carbon dioxide concentration on the growth
of CaUistephus chinensis cultivar Johannistag. Ann. Bot., 33: 351-365. Hughes, A.P. and Cockshull, K.E., 1971a. The effects of light intensity and carbon dioxide con-
centration on the growth of Chrysanthemum morifolium cv. Bright Golden Anne. Ann. Bot., 35: 899-914.
Hughes, A.P. and Cockshull, K.E., 1971b. The variation in response to light intensity and carbon
21
dioxide concentration shown by two cultivars of Chrysanthemum morifolium grown in con- trolled environment at two times of year. Ann. Bot., 35: 933-945.
Hughes, A.P. and Cockshull, K.E., 1972. Further effects of light intensity, carbon dioxide concen- tration, and day temperature on the growth of Chrysanthemum morifolium cv. Bright Golden Anne in controlled environment. Ann. Bot., 36: 533-550.
Hurd, R.G., 1968. Effects of C02 enrichment on the growth of young tomato plants in low light. Ann. Bot., 32: 531-542.
Imai, K., 1978. Effect of carbon dioxide concentration on growth and dry matter production of crop plants. V. Analysis of after-effect of carbon dioxide treatment on apparent photosynthesis. Jpn. J. Crop Sci., 47: 587-595.
Imai, K. and Murata, Y., 1978. Effect of carbon dioxide concentration on growth and dry matter production of crop plants. IV. After-effects of carbon dioxide-treatments on the apparent pho- tosynthesis, dark respiration and dry matter production. Jpn. J. Crop Sci., 47: 330-335.
Janes, B.E., 1970. Effect of carbon dioxide, osmotic potential of nutrient solution, and light inten- sity on transpiration and resistance to flow of water in pepper plants. Plant Physiol., 45: 95-103.
Jensen, H.E.K., 1980. Carbon dioxide for roses. Statens Planteavlsforseg, Denmark, 82: Rep. No. 1562, 4 pp. (in Danish).
Jensen, R.G., 1977. Ribulose-l,5-bisphosphate carboxylaseoxygenase. Annu. Rev. Plant Physiol., 28: 379-400.
Johal, S. and ChoUet, R., 1980. Ribulose-l,5-biphosphate carboxylase oxygenase. Enzymic, phy- siochemical and nutritional properties. What's New Plant Physiol., 11: 45-48.
Joliffe, P.A. and Tregunna, E.B., 1968. Effect of temperature, C02 concentration, and light inten- sity on oxygen inhibition of photosynthesis in wheat leaves. Plant Physiol., 43: 902-906.
Jones, P., Allen, L.H., Jones, J.W. and Valle, R., 1985. Photosynthesis and transpiration responses of soybean canopies to short- and long-term C02 treatments. Agron. J., 77:119-126.
Kimball, B.A. and Mitchell, S.T., 1979. Tomato yields from C02 enrichment in unventilated and conventionally ventilated greenhouses. J. Am. Soc. Hortic. Sci., 4: 515-520.
Klougart, A., 1978. CO2 - - the forgotten growth factor., Gartner Tidende, 4:50-52 (in Danish). Kobel, F. von, 1965. Der Einfluss der CO2-Anreicherung auf die Produktion yon Chrysanthem-
stecklingen. Gartenbauwissenschaft, 549: 549-556. Kriedemann, P.E. and Wong, S.C., 1984. Growth response and photosynthetic adaptation to car-
bon dioxide: Comparative behaviour in some C3 species. In: C. Sybesma (Editor), Advances in Photosynthesis Research. Vol. IV. Martinus Nijhoff, Junk, The Hague, Boston, Lancaster, pp. 209-212.
Laing, W.A., Ogren, W.L. and Hageman, R.H., 1974. Regulation of soybean net photosynthetic C02 fixation by the interaction of C02, 02, and ribulose 1,5-diphosphate carboxylase. Plant Physiol., 54: 678-685.
Lin, W.C. and Molnar, J.M., 1980. Carbonated mist and high intensity supplementary lighting for propagation of selected woody ornamentals. Proc. Int. Plant. Propag. Soc., 30: 104-109.
Lin, W.C. and Molnar, J.M., 1982. Supplementary lighting and C02 enrichment for accelerated growth of selected woody ornamental seedlings and rooted cuttings. Can. J. Plant Sci., 62: 703-707.
Lindemann, A., 1973. Wachstumsbeeinflussung dutch Anreicherung der Gerwiichshausluft mit Kohlendioxyd (C02) unter schiedlicher Dosierung. Zierpflanzenbau, 19: 778-779.
Lindstrom, R.S., 1965. Carbon dioxide and its effect on the growth of roses. Proc. Am. Soc. Hortic. Sci., 87: 521-524.
Lindstrom, R.S., 1968. Supplemental carbon dioxide and growth of Chrysanthemum morifolium Ramat. Proc. Am. Soc. Hortic. Sci., 92: 627-632.
L~bner, M., 1913. Nochmals fiber Diingung der Pflanzen mit Kohlens~iure. MSllers Dtsch. G~irt- ner-Zeitung, 28: 434-435.
Lundeg~rdh, H., 1924. Der Kreislauf der Kohlens~iure in der Natur. Gustav Fischer, Jena, 308 pp.
22
Madeen, E., 1968. Effect of C02 concentration on the accumulation of starch and sugar in tomato leaves. Physiol. Plant., 21: 169-175.
Madsen, E., 1973. The effect of CO2-concentration on development and dry matter production in young tomato plants. Acta Agric. Scand., 23: 235-240.
Mastalerz, J.W., 1968. Forcing lilies with supplementary fluorescent light and C02. Penn. Flower Grower Bull., 213: 8.
Matsumaru, T., Yoneyama, T., Totsuka, T. and Shiratori, K., 1979. Absorption of atmospheric NO2 by plants and soils. (I) Quantitative estimation of absorbed NO2 in plants by 15N method. Soil Sci. Plant Nutr., 25: 255-265.
Mattson, R.H. and Widmer, R.E., 1971. "Year round" effects of carbon dioxide-supplemented atmospheres on greenhouse rose (Rosa hybrida) production. J. Am. Soc. Hortic. Sci., 96: 487-488.
McKeag, R.J., 1965. Response of carnation to three concentrations of C02. Colo. Flower Grower Assoc. Bull., 187: 1-3.
Milhet, Y. and Costes, C., 1975. Effects of CO2 nutrition on growth and yield of muskmelon (Cuc- umis melo L. ), egg-plant (Solanum melongena L. ) and sweet-pepper ( Capsicum annuum L. ). Acta Hortic., 51: 201-211.
Moe, R., 1977. Effect of light, temperature and CO2 on the growth of Campanula isophylla stock plants and on the subsequent growth and development of their cuttings. Scientia Hortic., 6: 129-141.
Moe, R. and Mortensen, L.M., 1986. C02 enrichment in Norway. In: H.Z. Enoch and B. Kimball (Editors), Carbon Dioxide Enrichment of Greenhouse Crops. Vol. I. Status and C02 Sources. CRC Press, FL, pp. 59-73.
Molnar, J.M. and Cumming, W.A., 1968. Effect of carbon dioxide on propagation of softwood, conifer and herbaceous cuttings. Can. J. Plant Sci., 48: 595-599.
Monson, R.K., Stidham, M.A., Williams, G.J., III, Edwards, G.E. and Uribe, E.G., 1982. Temper- ature dependence of photosynthesis in Agropyron smithii Rydb. Plant Physiol., 69: 921-928.
Morison, J.I.L., 1985. Sensitivity of stomata and water use efficiency to high C02. Plant Cell Environ., 8: 467-474.
Morison, J.I.L. and Gifford, R.M., 1984. Ethylene contamination of C02 cylinders. Plant Physiol., 75: 275-277.
Mortensen, L.M., 1982. Charcoal as a carbon dioxide source in greenhouses. Gartenbauwissen- schaft, 47: 14-18.
Mortensen, L.M., 1983a. Air pollution and plant injuries in greenhouses. Dep. Floriculture and Greenhouse Crops, Agricultural University of Norway, Rep. 281: pp. 1-22 (in Norwegian).
Mortensen, L.M., 1983b. Growth responses of some greenhouse plants to environment. VIII. Effect of C02 on photosynthesis and growth of Norway spruce. Meld. Nor. Landbrukshoegsk., 62: 1-13.
Mortensen, L.M., 1983c. Growth responses of some greenhouse plants to environment. IX. Effect of C02 on photosynthesis of Chrysanthemum morifolium Ramat. at different light, tempera- ture and 02 levels. Meld. Nor. Landbrukshoegsk., 62: I-12.
Mortensen, L.M., 1983d. Growth responses of some greenhouse plants to environment. X. Long- term effect of CO2 enrichment on photosynthesis, photorespiration, carbohydrate content and growth of Chrysanthemum morifolium Ramat. Meld. Nor. Landbrukshoegsk., 62: 1-11.
Mortensen, L.M., 1983e. Growth responses of some greenhouse plants to environment. XII. Effect of C02 on photosynthesis and growth of Saintpaulia ionantha, Kalanchoe blossfeldiana and Nephrolepis exaltata. Meld. Nor. Landbrukshoegsk., 62: 1-16.
Mortensen, L.M., 1985a. Effects of CO2 enrichment and supplementary light on growth and flow- ering of poinsettia, Euphorbia pulcherrima Willd. Meld. Nor. Landbrukshoegsk., 64: 1-8.
Mortensen, L.M., 1985b. Nitrogen oxides produced during C02 enrichment. I. Effects on different greenhouse plants. New Phytol., 101: 103-108.
23
Mortensen, L.M., 1985c. Nitrogen oxides produced during C02 enrichment. II. Effects on different tomato and lettuce cultivars. New Phytol., 101: 411-415.
Mortensen, L.M., 1986a. C02 during ventilation to cucumber and roses. Gartneryrket, 76:140 (in Norwegian).
Mortensen, L.M., 1986b. Effect of intermittent as compared to continuous C02 enrichment on growth and flowering of Chrysanthemum × mori[olium Ramat. and Saintpaulia ionantha H. Wendl. Scientia Hortic., 29: 283-289.
Mortensen, L.M., 1986c. Nitrogen oxides produced during C02 enrichment. III. Effects on tomato at different photon flux densities. New Phytol., 104: 653-660.
Mortensen, L.M. and Moe, R., 1983a. Growth responses of some greenhouse plants to environ- ment. IV. Effects of carbon dioxide on photosynthesis and growth of Chrysanthemum mori- folium Ramat. Meld. Nor. Landbrukshoegsk., 61: 1-11.
Mortensen, L.M. and Moe, R., 1983b. Growth responses of some greenhouse plants to environ- ment. V. Effect of CO2, 02 and light on net photosynthetic rate in Chrysanthemum morifolium Ramat. Scientia Hortic., 19: 133-140.
Mortensen, L.M. and Moe, R., 1983c. Growth responses of some greenhouse plants to environ- ment. VI. Effect of C02 and artificial light on growth of Chrysanthemum mori[olium Ramat. Scientia Hortic., 19: 141-147.
Mortensen, L.M. and Moe, R., 1983d. Growth responses of some greenhouse plants to environ- ment. VII. The effect of C02 on photosynthesis and growth of roses. Meld. Nor. Landbruksh- oegsk., 62: 1-11.
Mortensen, L.M. and Ulsaker, R., 1985. Effect of C02 concentration and light levels on growth, flowering and photosynthesis of Begonia × hiemalis Fotsch. Scientia Hortic., 27: 133-141.
Mortimer, D.C., 1959. Some short-term effects of increased carbon dioxide concentration on pho- tosynthetic assimilation in leaves. Can. J. Bot., 37: 1191-1201.
Miinch, J. and Leinfelder, J., 1967. Ergebnis einer zusiitzlichen Begasung mit C02 bei Saintpau- lien. Gartenwelt, 67: 250-252.
Miinch, J. and Leinfelder, J., 1968. Wirkung zustitzlicher Begasung mit C02 auf Alphelandra squarrosa 'Typ KSniger'. Gartenwelt, 68: 239-241.
Nelson, P.V. and Larson, R.A., 1969. The effect of increased C02 concentrations on chrysanthe- mum (C. morifolium) and snapdragon (Antirrhinum majus). N. C. Agric. Exp. Stn. Tech. Bull. No. 194, pp. 1-15.
Newton, P., 1965. Growth of Cucumis sativus, variety Butcher's Disease Resister, with two con- centrations of carbon dioxide. Ann. Appl. Biol., 56: 55-64.
Owen, 0., Small, T. and Williams, P.H., 1926. Carbon dioxide in relation to glasshouse crops. Part III. The effect of enriched atmospheres on tomatoes and cucumber. Ann. Appl. Biol., 13: 560-576.
Papenhagen, A., 1983. Bessere Ertriige durch C02 - - abet nicht iiberall. GRrtnerbSrse Gartenwelt, 49: 1244-1249.
Peet, M.M., 1986. Acclimation to high C02 in monoecious cucumbers. I. Vegetative and repro- ductive growth. Plant Physiol., 80: 59-62.
Peet, M.M., Huber, S.C. and Patterson, D.T., 1986. Acclimation to high C02 in monoecious cuc- umbers. II. Carbon exchange rates, enzyme activities, and starch and nutrient concentrations. Plant Physiol., 80: 63-67.
Reimherr, P., 1984. C02 und Zusatzlicht bei Impatiens repens und Pavonia multiflora Dtsch. Gartenbau, 51/52: 2313-2314.
Reimherr, P., 1985a. CO2 und Zusatzlicht bei Cissus antarctica und Sche[flera actinophylla. Dtsch. Gartenbau, 1: 10-11.
Reimherr, P., 1985b. CO2 und Zusatzlicht bei Ficus benjamina. Dtsch. Gartenbau, 4: 170. Reuther, G. and Forschner, W., 1983. Die Reaktion yon Pelargonienstecklingen auf Licht und
C02~Begasung in der Bewurzelungsphase. Zierpflanzenbau, 23: 948-954. Riis Lavsen, E., 1967. Studies on C02 for pot plants. Gartner Tidende, 41:625-628 (in Danish).
24
Rogers, H.H., Sionit, N., Cure, J.D., Smith, J.M. and Bingham, G.E., 1984. Influence of elevated carbon dioxide on water relations of soybeans. Plant Physiol., 74: 233-238.
Salisbury, F.B. and Ross, C., 1969. Plant Physiology. Wadsworth, Belmont, CA, 194 pp. Sasek, T.W., DeLucia, E.H. and Strain, B.R., 1985. Reversibility of photosynthetic inhibition in
cotton after long-term exposure to elevated C02 concentrations. Plant Physiol., 78: 619-622. Saussure, T., de, 1804. Recherches Chimiques sur la V~g~tation. Nyon, Paris, 327 pp. Saxe, H., 1981. Growth reduction by NOx during C02 enrichn~ent in the greenhouses. Ugeskr.
Jordbruk, 28:406-409 (in Danish). Saxe, H. and Christensen, O.V., 1985. Effects of carbon dioxide with and without nitric oxide
pollution on growth, morphogenesis and production time of pot plants. Environ. Pollut., 38: 159-169.
Saxe, H., Andersen, A., Buchart, B. and Enoch, H.Z., 1985. Summer C02 for tomato. Gartner Tidende, 51:1655-1659 (in Danish).
Schapendonk, A.H.C.M. and Gaastra, P., 1984. A simulation study on C02 concentration in pro- tected cultivation. Scientia Hortic., 23: 217-229.
Schickedanz, F. and Gommlich, H., 1968. Der Einfluss einer C02-Diingung auf Entwicklung und Bliitenbildung bei Saintpaulien. Gartenwelt, 68:417-419.
Schmidt, K., 1985. Die Kultur yon Elatiorbegonien im Winterhalbjahr. Dtsch. Gartenbau, 39: 1264-1266.
Schmidt, K., 1986. C02-Diingung erlaubt zwei Anthurien-Kulturen je Jahr. G~irtenbSrse Garten- welt, 4: 163-165.
Schmidt, K. and Brundert, W., 1984. C02 fdrdert Hydropflanzen. G~irtnerbSrse Gartenwelt, 22: 547-549.
Schmidt, K. and Lauterbach, D., 1985a. Xeromorphe Pflanzen in Hydrokultur. Kohlensiiure tags oder nachts? Dtsch. Gartenbau, 30: 1442-1443.
Schrnidt, K. and Lauterbach, D., 1985b. Hydrokultur und CO2-Diingung bei Kalancho~-Hybriden. Dtsch. Gartenbau, 37: 1740-1741.
Sebesta, Z. and Reiersen, D., 1981. A comparison of single glass and double acrylic sheeting with respect to heat loss and effects on plant environment. Acta Hortic., 115: 409-416.
Siren, G. and Alden, T., 1972. CO2 supply and its effects on the growth of conifer seedlings grown in a plastic greenhouse. R. Coll. For., Stockholm, Res. Note No. 37, 15 pp.
Skoye, D.A. and Toop, E.W., 1973. Relationship of temperature and mineral nutrition to carbon dioxide enrichment in the forcing of pot chrysanthemums. Can. J. Plant Sci., 53:609-614.
Slack, G. and Hand, D.W., 1985. The effect of winter and summer C02 enrichment on the growth and fruit yield of glasshouse cucumber. J. Hortic. Sci., 4: 507-516.
Slobbe, A., 1964. Carbon dioxide in autumn cucumber. Tuinderij, 17:954-955 (in Dutch). Small, T. and White, H.C., 1930. Carbon dioxide in relation to glasshouse crops. Part IV. The
effect on tomatoes of an enriched atmosphere maintained by means of a stove. Ann. Appl. Biol., 17: 81-89.
Spierings, F.H.F.G., 1971. Influence of fumigation with NO2 on growth and yield of tomato plants. Neth. J. Plant Pathol., 77: 194-200.
Taylor, O.C. and Eaton, F.M., 1966. Suppression of plant growth by nitrogen oxide. Plant Physiol., 41: 132-135.
Thompson, C.J. and Hanan, J.J., 1976. Effect of C02 concentration on roses: If. Yield. Colo. Flower Grower Assoc. Bull., 307: 1-2.
Thorsrud, A., 1926. Carbon dioxide enrichment and electrical heating. Nor. Gartnerforenings Tidssk., 16:133-136 (in Norwegian).
Tinus, R.A., 1972. CO2 enriched atmosphere speeds growth of Ponderosa pine and blue spruce seedlings. Tree Planters' Note, 23: 12-15.
Tolley, L.C. and Strain, B.R., 1984. Effects of CO2 enrichment and water stress on growth of Liquidambar stipaciflua and Pinus taeda seedlings. Can. J. Bot., 62: 2135-2139.
25
Tsujita, M.J., 1983. Tips on carbon dioxide and high-intensity lighting for good winter production. Minn. State Florists Bull., 6: 1-6.
Uffelen, J.A.M., van, 1975. Paprika-onderzoek. Stookteelt 1975. Groenten Fruit, 31: 658-659. Van Os, P., 1983. Positief effect van CO2 bij freesia. Vakbl. Bloemisterij, 49: 42-43. Verboom, H. and van Staaveren, M.C., 1978. Toediening van CO2 bij Alstroemeria. Vakbl. Bloem-
isterij, 33: 61. Vijverberg, A.J. and van Uffelen, J.A.M., 1977. The application of CO2 in the culture of sweet
peppers. Acta Hortic., 58: 293-296. Walla, I. and Kristoffersen, T., 1974. The effect of C02 application under various light and tem-
perature conditions on growth and development of some florist crops. Meld. Nor. Landbruksh- oegsk., 53:1-46 (in Norwegian).
Werth, A.J., 1914. Gemtiseanbauversuche auf Schleswig-Holsteinischen Mooren. Gartenwelt, 18: 447-449.
Winden, W.P., van, 1962. De teelt van sla met toediening van CO2. Groenten Fruit, 17: 1780-1781. Winter, E., 1913. Kohlens~iure zur Erniihrung der Pflanzen. Gartenflora, 62: 402-404. Wittwer, S.H., 1966. Application of carbon dioxide for vegetable growing under glass or plastic.
Acta Hortic., 4: 129-134, Wittwer, S.H. and Robb, W.M., 1964. Carbon dioxide enrichment of greenhouse atmospheres for
food crop production. Econ. Bot., 18: 34-56. Woltering, E.J., 1985. Bltiten- und Blattfall durch Stressfaktor ~,thylen. G~irtnerbSrse Gartenwelt,
34: 1303-1305. Woltz, S.S., 1969. Effects of accumulation of excess photosynthate in chrysanthemum leaves.
Proc. Fla. State Hortic. Soc., 82: 350-352. Woltz, S.S. and Engelhard, A.W., 1971. Physiological disorders of leaves of chrysanthemum cul-
tivars relative to accumulation of excess carbohydrate. Proc. Fla. State Hortic. Soc., 84: 370-374. Yeatman, C.W., 1970. C02 enriched air. Increased growth of conifer seedlings. Technical Notes,
Forestry Chronicle, June 1970, pp. 229-230. Yoneyama, T., Sasakawa, H., Ishizuka, S. and Totsuka, T., 1979. (II) Nitrite accumulation, nitrite
reductase activity and diurnal change of NO2 absorption in leaves. Soil Sci. Plant Nutr., 25: 267-275.
Zeevaart, A.J., 1976. Some effects of fumigating plants for short periods with NO2. Environ. Pol- lut., 11: 97-108.
Zieslin, N., Halevy, A.H. and Enoch, Z., 1972. The role of CO2 in increasing the yield of 'Baccara' roses. Hortic. Res., 12: 97-100.
Zimmerman, P.W., Crocker, W. and Hitchcock, A.E., 1933. The effect of carbon monoxide on plants. Contrib. Boyce Thompson Inst. Plant Res., 5:195 - 211.