Directory UMM :Data Elmu:jurnal:S:Scientia Horticulturae:Vol85.Issue1-2.July2000:
Scientia Horticulturae 85 (2000) 113±121
The effect of two day±night temperature regimes and
two nutrient solution concentrations on growth
of Lavandula angustifolia `Munstead' and
Magnolia soulangiana
Michal Bielenina,*, Marten K. Joustrab
a
Research Institute of Pomology and Floriculture, ul. Pomologiczna 18,
96±100 Skierniewice, Poland
b
Research Station for Nursery Stock, PB 118, 2770 AC Boskoop, Netherlands
Accepted 24 October 1999
Abstract
Young plants of Magnolia soulangiana and Lavandula angustifolia `Munstead' were given two
concentrations of nutrient solution (EC 0.8 or 1.6 mS cmÿ1) under negative or positive DIF
regimes. Magnolia exposed to warm nights and cool days grew slower than under positive DIF
treatment but root growth was not in¯uenced. The plant's architecture was not altered signi®cantly
except for shorter internodes number 2, 3, 4 and 5 on the main shoot under negative DIF treatment.
Negative DIF resulted also in reduced length of internodes and enhanced ¯owering of Lavandula
without an adverse effect on plant growth. Only the dry matter content of the shoots was reduced.
Use of nutrient solution with EC 1.6 mS cmÿ1 resulted in decreased height of Magnolia and
drastically reduced growth but stimulated ¯owering of Lavandula comparing to nutrient solution of
EC 0.8 mS cmÿ1. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: DIF; Growth; Lavandula angustifolia; Magnolia soulangiana; Nutrient concentration;
Temperature
Abbreviations: DIF, difference between day and night temperatures; EC, electrical conductivity
*
Corresponding author. Research Institute of Pomology and Floriculture, ul. WarynÂskiego 14,
96±100 Skierniewice, Poland. Tel.: 48-601-385842.
E-mail address: [email protected] (M. Bielenin)
0304-4238/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 9 9 ) 0 0 1 3 1 - 4
114
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
1. Introduction
Greenhouse cultivation of trees and shrubs can signi®cantly hasten plants
growth, and consequently, shorten a production cycle. Unfortunately, for some
species also negative effects of protected cultivation are observed which can
include excessive internode elongation, poor branching, inhibition of root growth
as well as reduction in ¯owering. Therefore, treatments or techniques that would
prevent these changes are required.
Lower day than night temperatures or negative DIF (Erwin et al., 1989) can
reduce stem elongation and result in more compact plants. This was observed,
among others, on Dendranthema grandi¯ora (Cockshull et al., 1995), Euphorbia
pulcherrima (Berghage and Heins, 1991), Fuchsia hybrida (Erwin et al., 1991),
Campanula isophylla (Moe, 1990) and Lilium longi¯orum (Erwin et al., 1989).
Also Zieslin and Tsujita (1988) showed that negative DIF resulted in signi®cantly
shorter stems of Easter lilies `Nellie White', while the same phenomenon on roses
was reported by Van den Berg (1984). Even though a complete physiological
explanation of the DIF effect is still not known, it was suggested that DIF
treatments bring about changes in endogenous gibberellin levels with GA1 being
mostly involved (Myster et al., 1995). Additionally, photoperiod and far-red light
were proved to in¯uence the DIF effect, probably through modi®cation of
gibberellin biosynthesis (Moe et al., 1995). Moreover, ¯uctuations between day
and night temperatures also affect the water vapour pressure de®cit gradient of
the air thus altering the transpiration and nutrient uptake of the plants (SchuÈssler,
1995).
On the other hand, it is well known that water availability in¯uences the
vegetative growth of plants. A decreased difference between the water potential
of the roots and the soil results in reduced water uptake of the plants, and
consequently, growth retardation (Hendriks and Ueber, 1995). A positive effect of
drought stress on quality of poinsettia was reported by Roeber and Horn (1993)
while a high concentration of nutrient solution was found to affect the growth
characteristic of Pelargonium zonale resulting in more compact plants (Leeuwen,
1994).
Magnolia soulangiana and Lavandula are important nursery plants, valued for
their attractive ¯owers. Both species, when grown in a greenhouse, can reach a
saleable size much faster than in outside beds. Detailed procedures for
greenhouse production of these species have not been developed but usually
they are grown under positive DIF and fertigated with nutrient solution of
EC 0.8 mS cmÿ1. Unfortunately, loss in plant quality during protected
cultivation limits the commercial use of this technology. The main problems
encountered during greenhouse cultivation are poor branching and excessive
elongation growth of Magnolia and loose growth habit and sparse ¯owering of
Lavandula (Joustra, 1994a,b). Thus, it is interesting to see whether the use of
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
115
negative DIF treatment and an increase in the concentration of nutrient solution
can help to produce plants of higher quality.
The objective of this study was to evaluate the effects of two DIF treatments
and two concentrations of nutrient solution on plant growth pattern and quality of
greenhouse grown Lavandula angustifolia `Munstead' and Magnolia soulangiana.
2. Materials and methods
Rooted cuttings of Lavandula angustifolia `Munstead' and one-year-old plants
of Magnolia soulangiana obtained from a commercial grower were used as
planting material. After overwintering in a cool greenhouse they were potted in
2 dm3 (Lavandula) or 3 dm3 (Magnolia) containers and placed on tables with
an intermittent ¯ooding system under conditions of positive or negative DIF
(Table 1). In each compartment two concentrations of nutrient solution were
tested, i.e., `low' with an EC value of 0.8 mS cmÿ1 and `high' with an EC value
of 1.6 mS cmÿ1 (for data on composition of the solution, see Table 2). There were
36 plants in each treatment organised in two replicates. The trial was started on
20th January and plants were grown under the natural photoperiod in Boskoop,
The Netherlands. After placing in the greenhouse, the Magnolia plants were cut
Table 1
Actual average day and night temperatures (8C) in greenhouse compartments during the experiment
Week of experiment
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Positive DIF
Negative DIF
Day
Night
Mean
Day
Night
Mean
15.1
15.3
17.2
22.4
18.8
20.4
20.4
21.6
22.1
23.7
22.8
24.0
25.2
24.9
24.6
26.5
25.3
10.5
10.5
8.9
12.0
11.7
12.6
12.6
13.3
13.6
14.0
13.5
14.0
14.5
14.3
15.1
15.2
15.6
12.2
12.3
12.1
15.6
14.7
15.9
16.0
17.0
17.5
18.7
18.4
19.2
20.2
20.3
20.6
21.7
21.4
12.0
11.8
13.6
17.5
15.1
17.1
18.2
19.3
19.5
21.5
21.0
21.2
22.7
23.8
22.4
24.3
22.8
13.8
13.7
12.3
14.1
15.3
17.0
17.3
17.5
17.6
19.1
18.0
18.4
18.7
19.6
19.5
19.8
19.8
13.2
13.0
12.6
14.9
14.8
16.6
17.4
17.8
18.0
19.9
19.2
19.4
20.3
21.4
20.9
22.0
21.3
116
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
Table 2
Concentration and composition of nutrient solutions (in both treatments, the same amount of
micronutrients was incorporated into the potting mix as a PG-Mix fertiliser)
Treatment
Low nutrient concentration
High nutrient concentration
EC
(mS cmÿ1)
0.8
1.6
Nutrient concentration (mmol dmÿ3)
NOÿ
3
H2 POÿ
4
SOÿ
4
NH
K
4
6.50
13.0
0.50
1.00
0.75
1.50
0.75
1.50
Mg2 Ca2
2.25 0.75
4.50 1.50
2.00
4.00
above the highest viable bud. The plants of both species were harvested after 17
weeks of growth. The total sum of solar radiation upon the greenhouse during the
experiment was 1134 MJ mÿ2.
For Lavandula the height and width of plants, number of shoots per plant
and mean length of fully grown internodes as well as the number of ¯owering
plants were recorded. Approximate plant volume was calculated from height
and width measurements using the equation for the volume of a cylinder
(V 14 p height width2 ). The fresh and dry weights of the above-ground
parts of the plants were measured and the dry matter content of shoots was
calculated.
The length of main and side shoots, number of side shoots, dry weight of root
system as well as fresh and dry weight of shoots were measured for Magnolia.
Dry matter content of shoots was calculated as dry to fresh weight ratio. To
evaluate the effect of DIF and nutrient concentration treatments on the length of
consecutive internodes on the main shoot of Magnolia, the corresponding
internodes were compared between treatments when elongation stopped. Analysis
of variance (ANOVA) was performed to establish signi®cant differences between
treatments according to Student's t-test.
3. Results and discussion
3.1. Lavandula angustifolia Munstead
No interaction between temperature and nutrient treatments was observed.
There was no difference in height/width ratio or plant volume between
temperature treatments (Table 3) and the number of shoots and fresh weight
were not affected either. Thus, it can be concluded that plant growth was not
reduced. However, negative DIF treatment resulted in shorter internodes and
lower dry matter content. The latter agrees with the results of Zieslin and Tsujita
(1988) on lilies and may be attributed to higher respiration at night and reduced
photosynthesis during the day. Contrary to the results on some short-day plants
(Moe, 1993; Mortensen, 1994), ¯owering was signi®cantly enhanced by negative
117
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
Table 3
Effect of temperature regime and concentration of nutrient solution on growth of Lavandula
angustifolia `Munstead'
DIF
Height/width
Volume
No. of shoots per plant
Mean length of internode (mm)
Shoot fresh weight (g)
Dry matter content of shoots (%)
Solution concentration
Negative
LSD
Positive
High
LSD
Low
0.58
6.34
36.1
13
46.3
16.1
0.04nsa
1.2ns
3.1ns
1.1a
8.6ns
0.9a
0.57
6.42
34.9
15.0
43.6
18.3
0.58
5.80
33.4
14.0
40.7
18.0
0.03ns
1.0a
2.6a
0.9a
7.0a
0.7a
0.59
6.96
37.1
15.0
49.4
17.1
a
Differences signi®cant at P < 0.05 level or not signi®cant (ns) according to Student's t-test. No
interaction was signi®cant.
DIF (Fig. 1). This effect might result from changes in GA3 activity in the plant
tissue as suggested by Moe (1990).
The high concentration of nutrient solution did not change the shape of plants
(height/width ratios were the same in both EC treatments) but it reduced plants'
growth, as height, width, volume of plants and number of shoots were lower in
this treatment. Also length of internodes as well as fresh weight of shoots were
reduced. However, dry weight was unaffected, which resulted in higher dry
matter content. Moreover, ¯owering was improved in this treatment (Fig. 1). In
Fig. 1. Effect of temperature treatment and concentration of nutrient solution on ¯owering of
Lavandula angustifolia `Munstead' grown in greenhouse (error bars represent S.E. for means).
118
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
the light of the results it seems that the nutrient concentration of EC
1.6 mS cmÿ1 was too high for Lavandula cultivated in the intermittent ¯ooding
system and the adverse effects on growth may be explained as the consequences
of salinity stress.
We suggest that negative DIF treatment can be used commercially to control
shoot elongation in Lavandula during spring. The ¯ower stimulation observed
under negative DIF and high nutrient concentration was still not enough for
commercial growing as plants grown outside ¯ower very easily. On the other
hand, the increase in ¯owering compared to standard greenhouse conditions was
very promising and may help to identify the factors important for ¯ower initiation
in Lavandula.
3.2. Magnolia soulangiana
In general, plants from the negative DIF treatment were smaller than those
from positive DIF. Both main and side shoots were shorter while the number of
shoots as well as the fresh and dry weight of shoots were lower. It seems that, as
in the case of Lavandula, these results can be attributed to higher night respiration
and lower photosynthesis rates under negative DIF. The growth of roots was
similar in both temperature treatments, however (Table 4). Lengths of fully-grown
internodes number 2, 3, 4, and 5 (counting from the stem base) were lower under
negative DIF but the difference was the most evident for internodes 2, 3 and 4
(Fig. 2). The length of the ®rst internode on the shoot was very low in all
treatments and differences were not statistically signi®cant. The length of
internode number 6 did not differ signi®cantly between temperature treatments at
5% level of signi®cance. Even though negative DIF changes the growth
characteristics of Magnolia soulangiana the effect is, unlike that on Lavandula,
limited to the ®rst stages of growth (except for the ®rst internode on the shoot). A
Table 4
Growth of Magnolia soulangiana under positive and negative DIF regimes and two concentrations
of nutrient solution
DIF
Length of main shoot (cm)
Total length of side shoots (cm)
No. of shoots per plant
Shoot fresh weight (g)
Dry matter content of shoots (%)
Dry weight of roots (g)
Solution concentration
Negative
LSD
Positive
High
LSD
Low
29.0
26.9
2.1
42.4
20.3
2.56
2.9a
6.5a
0.2a
6.2a
0.3a
0.6ns
41.4
43.9
2.4
54.4
20.7
2.77
35.5
37.1
2.4
49.9
20.2
2.58
2.3a
5.3ns
0.2ns
5.1ns
0.2a
0.5ns
38.5
38.2
2.3
51.2
20.5
2.69
a
Differences signi®cant at P < 0.05 level or not signi®cant (ns) according to Student's t-test. No
interaction was signi®cant.
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
119
Fig. 2. Effect of temperature treatment and concentration of nutrient solution on length of
consecutive internodes on main shoot of Magnolia soulangiana grown in greenhouse (error bars
represent S.E. for means).
different action of DIF depending on growth stage was also reported by Sach
(1995). Less pronounced differences between treatments in late spring can also
come from the longer photoperiod stimulating gibberellin biosynthesis which
nulli®es the effect of negative DIF (Moe et al., 1995). Additionally, negative DIF
conditions become dif®cult to obtain during late spring. Thus, the procedure
cannot be seen as an ef®cient tool for reducing ®nal length of internodes
throughout the production cycle during greenhouse cultivation of this species.
However, negative DIF can help to control excessive internode elongation at the
beginning of the growing season (Fig. 2) which can be important when protecting
structures are used only to force plant growth in the spring. Moreover, good root
growth combined with reduced shoot growth can make the acclimation of
greenhouse plants to outside conditions much easier.
High nutrient concentrations reduced the length of the main shoot (Table 4) but
had no effect on length of internodes (Fig. 2). So the reduction of main shoot
length (which was also observed on Pelargonium by Leeuwen (1994)) came in
this treatment exclusively from a lower number of internodes on the shoot which
suggests slower shoot development. However, neither the length of the side shoots
nor the number of shoots were changed (Table 4). Thus, we can conclude that a
high level of nutrients results in somewhat smaller but not much more compact
plants even though main shoot domination is slightly suppressed. A high nutrient
120
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
concentration also resulted in a lower dry matter content of shoots, while the fresh
weight of shoots as well as the dry weight of roots were unaffected. These suggest
that the nutrient concentrations tested in the experiment fall within the range of
tolerance for Magnolia but they failed to in¯uence the plants' growth pattern
signi®cantly.
4. Conclusions
1. Negative DIF reduces the length of internodes on Lavandula without an
adverse effect on growth.
2. Magnolia grows slower when exposed to negative DIF conditions but changes
in the plant's architecture are limited and the length of internodes is reduced
only at the beginning of the growing season.
3. Negative DIF enhances ¯owering of Lavandula.
4. A higher nutrient concentration reduces growth of both Magnolia and
Lavandula, the latter being much more affected supposedly due to a higher
sensitivity to salinity stress.
Acknowledgements
The experiments were conducted in Research Station for Nursery Stock,
Boskoop, The Netherlands, as a part of the extended research project on the effect
of physical conditions on growth of nursery plants in greenhouse. We would like
to thank J.H.M. Sievierink, for his work on the statistical data analysis as well as
A.J. van Fulpen and M.R. Blanken for their technical assistance.
References
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poinsettia. J. Am. Soc. Hort. Sci. 116 (1), 14±18.
Cockshull, K.E., Langton, F.A., Cave, C.R.J., 1995. Differential effects of different DIF treatments
on chrysanthemum and poinsettia. Acta Hort. 378, 15±25.
Erwin, J.E., Heins, R.D., Karlsson, M.G., 1989. Thermomorphogenesis in Lilium longi¯orum. Am.
J. Bot. 76 (1), 47±52.
Erwin, J.E., Heins, R.D., Moe, R., 1991. Temperature and photoperiod effects on Fuchsia hybrida morphology. J. Am. Soc. Hort. Sci. 116 (6), 960±995.
Hendriks, L., Ueber, E., 1995. Alternative methods of regulating the elongation growth of
ornamental plants: a current assessment. Acta Hort. 378, 159±163.
Joustra, M.K., 1994a. Orientatie op effecten van de klimaatsfactoren licht, temperatuur en
luchtvochtigheid op de groei van boomkwekerijgewassen in pot. Proefstation voor de
Boomkwekerij, Boskoop, Rapp. 25.
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Joustra, M.K., 1994b. Zoeken naar optimale kastemperatuur in het voorjaargewassen indelen naar
klimaatreaktie. De Boomkwekerij 7 (2), 22±23.
van Leeuwen, G.J.L., 1994. Remstoffen kunnen overbodig zijn. Vakblad voor de Bloemisterij 1,
38±39.
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stem elongation and ¯owering of the long-day plant Campanula isophylla Moretti. Sci. Hort. 43,
291±305.
Moe, R., 1993. Control of plant morphogenesis and ¯owering by temperature alternations. Flow.
Newsletter 15, 30±34.
Moe, R., Willumsen, K., Ihlebekk, I.H., Stupa, A.I., Glomsrud, N.M., Mortensen, L.M., 1995. DIF
and temperature drop responses in SDP and LDP, a comparison. Acta Hort. 378, 27±33.
Mortensen, L.M., 1994. Effects of day/night temperature variations on growth, morphogenesis and
¯owering of Kalanchoe blossfeldiana v. Poelln. at different CO2 concentrations, daylengths and
photon ¯ux densities. Sci. Hort. 59, 233±241.
Myster, J., Moe, R., Juntilla, O., 1995. Does diurnal temperature ¯uctuations (DIF) regulate
internode lengths mediated through the biosynthetic formation of GA1 in Begonia hiemalis
Fotch? Acta Hort. 378, 123±128.
Roeber, R., Horn, W., 1993. Wirkung unterschiedlicher Wassergaben auf Wachstum, QualitaÈt und
Prolingegalt von Euphorbia pulcherrima Willd. ex Klotzsch. Gartenbauwiss. 58, 15±20.
Sach, L., 1995. The effect of difference in temperature regimes (DIF) on pot chrysanthemums and
bedding plants. Acta Hort. 378, 81±86.
SchuÈssler, H.K., 1995. Effect of various water vapour pressure de®cit gradients and nitrogen levels
on morphogenesis of Euphorbia pulcherrima `Freedom'. Acta Hort. 378, 149±157.
Van den Berg, G.A., 1984. In¯uence of higher night than day temperatures on the winter production
of `Sonia' roses under Dutch glasshouse conditions. Acta Hort. 148, 581±590.
Zieslin, K., Tsujita, M.J., 1988. Regulation of stem elongation of lilies by temperature and the effect
of gibberellin. Sci. Hort. 37, 165±169.
The effect of two day±night temperature regimes and
two nutrient solution concentrations on growth
of Lavandula angustifolia `Munstead' and
Magnolia soulangiana
Michal Bielenina,*, Marten K. Joustrab
a
Research Institute of Pomology and Floriculture, ul. Pomologiczna 18,
96±100 Skierniewice, Poland
b
Research Station for Nursery Stock, PB 118, 2770 AC Boskoop, Netherlands
Accepted 24 October 1999
Abstract
Young plants of Magnolia soulangiana and Lavandula angustifolia `Munstead' were given two
concentrations of nutrient solution (EC 0.8 or 1.6 mS cmÿ1) under negative or positive DIF
regimes. Magnolia exposed to warm nights and cool days grew slower than under positive DIF
treatment but root growth was not in¯uenced. The plant's architecture was not altered signi®cantly
except for shorter internodes number 2, 3, 4 and 5 on the main shoot under negative DIF treatment.
Negative DIF resulted also in reduced length of internodes and enhanced ¯owering of Lavandula
without an adverse effect on plant growth. Only the dry matter content of the shoots was reduced.
Use of nutrient solution with EC 1.6 mS cmÿ1 resulted in decreased height of Magnolia and
drastically reduced growth but stimulated ¯owering of Lavandula comparing to nutrient solution of
EC 0.8 mS cmÿ1. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: DIF; Growth; Lavandula angustifolia; Magnolia soulangiana; Nutrient concentration;
Temperature
Abbreviations: DIF, difference between day and night temperatures; EC, electrical conductivity
*
Corresponding author. Research Institute of Pomology and Floriculture, ul. WarynÂskiego 14,
96±100 Skierniewice, Poland. Tel.: 48-601-385842.
E-mail address: [email protected] (M. Bielenin)
0304-4238/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 9 9 ) 0 0 1 3 1 - 4
114
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
1. Introduction
Greenhouse cultivation of trees and shrubs can signi®cantly hasten plants
growth, and consequently, shorten a production cycle. Unfortunately, for some
species also negative effects of protected cultivation are observed which can
include excessive internode elongation, poor branching, inhibition of root growth
as well as reduction in ¯owering. Therefore, treatments or techniques that would
prevent these changes are required.
Lower day than night temperatures or negative DIF (Erwin et al., 1989) can
reduce stem elongation and result in more compact plants. This was observed,
among others, on Dendranthema grandi¯ora (Cockshull et al., 1995), Euphorbia
pulcherrima (Berghage and Heins, 1991), Fuchsia hybrida (Erwin et al., 1991),
Campanula isophylla (Moe, 1990) and Lilium longi¯orum (Erwin et al., 1989).
Also Zieslin and Tsujita (1988) showed that negative DIF resulted in signi®cantly
shorter stems of Easter lilies `Nellie White', while the same phenomenon on roses
was reported by Van den Berg (1984). Even though a complete physiological
explanation of the DIF effect is still not known, it was suggested that DIF
treatments bring about changes in endogenous gibberellin levels with GA1 being
mostly involved (Myster et al., 1995). Additionally, photoperiod and far-red light
were proved to in¯uence the DIF effect, probably through modi®cation of
gibberellin biosynthesis (Moe et al., 1995). Moreover, ¯uctuations between day
and night temperatures also affect the water vapour pressure de®cit gradient of
the air thus altering the transpiration and nutrient uptake of the plants (SchuÈssler,
1995).
On the other hand, it is well known that water availability in¯uences the
vegetative growth of plants. A decreased difference between the water potential
of the roots and the soil results in reduced water uptake of the plants, and
consequently, growth retardation (Hendriks and Ueber, 1995). A positive effect of
drought stress on quality of poinsettia was reported by Roeber and Horn (1993)
while a high concentration of nutrient solution was found to affect the growth
characteristic of Pelargonium zonale resulting in more compact plants (Leeuwen,
1994).
Magnolia soulangiana and Lavandula are important nursery plants, valued for
their attractive ¯owers. Both species, when grown in a greenhouse, can reach a
saleable size much faster than in outside beds. Detailed procedures for
greenhouse production of these species have not been developed but usually
they are grown under positive DIF and fertigated with nutrient solution of
EC 0.8 mS cmÿ1. Unfortunately, loss in plant quality during protected
cultivation limits the commercial use of this technology. The main problems
encountered during greenhouse cultivation are poor branching and excessive
elongation growth of Magnolia and loose growth habit and sparse ¯owering of
Lavandula (Joustra, 1994a,b). Thus, it is interesting to see whether the use of
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
115
negative DIF treatment and an increase in the concentration of nutrient solution
can help to produce plants of higher quality.
The objective of this study was to evaluate the effects of two DIF treatments
and two concentrations of nutrient solution on plant growth pattern and quality of
greenhouse grown Lavandula angustifolia `Munstead' and Magnolia soulangiana.
2. Materials and methods
Rooted cuttings of Lavandula angustifolia `Munstead' and one-year-old plants
of Magnolia soulangiana obtained from a commercial grower were used as
planting material. After overwintering in a cool greenhouse they were potted in
2 dm3 (Lavandula) or 3 dm3 (Magnolia) containers and placed on tables with
an intermittent ¯ooding system under conditions of positive or negative DIF
(Table 1). In each compartment two concentrations of nutrient solution were
tested, i.e., `low' with an EC value of 0.8 mS cmÿ1 and `high' with an EC value
of 1.6 mS cmÿ1 (for data on composition of the solution, see Table 2). There were
36 plants in each treatment organised in two replicates. The trial was started on
20th January and plants were grown under the natural photoperiod in Boskoop,
The Netherlands. After placing in the greenhouse, the Magnolia plants were cut
Table 1
Actual average day and night temperatures (8C) in greenhouse compartments during the experiment
Week of experiment
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Positive DIF
Negative DIF
Day
Night
Mean
Day
Night
Mean
15.1
15.3
17.2
22.4
18.8
20.4
20.4
21.6
22.1
23.7
22.8
24.0
25.2
24.9
24.6
26.5
25.3
10.5
10.5
8.9
12.0
11.7
12.6
12.6
13.3
13.6
14.0
13.5
14.0
14.5
14.3
15.1
15.2
15.6
12.2
12.3
12.1
15.6
14.7
15.9
16.0
17.0
17.5
18.7
18.4
19.2
20.2
20.3
20.6
21.7
21.4
12.0
11.8
13.6
17.5
15.1
17.1
18.2
19.3
19.5
21.5
21.0
21.2
22.7
23.8
22.4
24.3
22.8
13.8
13.7
12.3
14.1
15.3
17.0
17.3
17.5
17.6
19.1
18.0
18.4
18.7
19.6
19.5
19.8
19.8
13.2
13.0
12.6
14.9
14.8
16.6
17.4
17.8
18.0
19.9
19.2
19.4
20.3
21.4
20.9
22.0
21.3
116
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
Table 2
Concentration and composition of nutrient solutions (in both treatments, the same amount of
micronutrients was incorporated into the potting mix as a PG-Mix fertiliser)
Treatment
Low nutrient concentration
High nutrient concentration
EC
(mS cmÿ1)
0.8
1.6
Nutrient concentration (mmol dmÿ3)
NOÿ
3
H2 POÿ
4
SOÿ
4
NH
K
4
6.50
13.0
0.50
1.00
0.75
1.50
0.75
1.50
Mg2 Ca2
2.25 0.75
4.50 1.50
2.00
4.00
above the highest viable bud. The plants of both species were harvested after 17
weeks of growth. The total sum of solar radiation upon the greenhouse during the
experiment was 1134 MJ mÿ2.
For Lavandula the height and width of plants, number of shoots per plant
and mean length of fully grown internodes as well as the number of ¯owering
plants were recorded. Approximate plant volume was calculated from height
and width measurements using the equation for the volume of a cylinder
(V 14 p height width2 ). The fresh and dry weights of the above-ground
parts of the plants were measured and the dry matter content of shoots was
calculated.
The length of main and side shoots, number of side shoots, dry weight of root
system as well as fresh and dry weight of shoots were measured for Magnolia.
Dry matter content of shoots was calculated as dry to fresh weight ratio. To
evaluate the effect of DIF and nutrient concentration treatments on the length of
consecutive internodes on the main shoot of Magnolia, the corresponding
internodes were compared between treatments when elongation stopped. Analysis
of variance (ANOVA) was performed to establish signi®cant differences between
treatments according to Student's t-test.
3. Results and discussion
3.1. Lavandula angustifolia Munstead
No interaction between temperature and nutrient treatments was observed.
There was no difference in height/width ratio or plant volume between
temperature treatments (Table 3) and the number of shoots and fresh weight
were not affected either. Thus, it can be concluded that plant growth was not
reduced. However, negative DIF treatment resulted in shorter internodes and
lower dry matter content. The latter agrees with the results of Zieslin and Tsujita
(1988) on lilies and may be attributed to higher respiration at night and reduced
photosynthesis during the day. Contrary to the results on some short-day plants
(Moe, 1993; Mortensen, 1994), ¯owering was signi®cantly enhanced by negative
117
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
Table 3
Effect of temperature regime and concentration of nutrient solution on growth of Lavandula
angustifolia `Munstead'
DIF
Height/width
Volume
No. of shoots per plant
Mean length of internode (mm)
Shoot fresh weight (g)
Dry matter content of shoots (%)
Solution concentration
Negative
LSD
Positive
High
LSD
Low
0.58
6.34
36.1
13
46.3
16.1
0.04nsa
1.2ns
3.1ns
1.1a
8.6ns
0.9a
0.57
6.42
34.9
15.0
43.6
18.3
0.58
5.80
33.4
14.0
40.7
18.0
0.03ns
1.0a
2.6a
0.9a
7.0a
0.7a
0.59
6.96
37.1
15.0
49.4
17.1
a
Differences signi®cant at P < 0.05 level or not signi®cant (ns) according to Student's t-test. No
interaction was signi®cant.
DIF (Fig. 1). This effect might result from changes in GA3 activity in the plant
tissue as suggested by Moe (1990).
The high concentration of nutrient solution did not change the shape of plants
(height/width ratios were the same in both EC treatments) but it reduced plants'
growth, as height, width, volume of plants and number of shoots were lower in
this treatment. Also length of internodes as well as fresh weight of shoots were
reduced. However, dry weight was unaffected, which resulted in higher dry
matter content. Moreover, ¯owering was improved in this treatment (Fig. 1). In
Fig. 1. Effect of temperature treatment and concentration of nutrient solution on ¯owering of
Lavandula angustifolia `Munstead' grown in greenhouse (error bars represent S.E. for means).
118
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
the light of the results it seems that the nutrient concentration of EC
1.6 mS cmÿ1 was too high for Lavandula cultivated in the intermittent ¯ooding
system and the adverse effects on growth may be explained as the consequences
of salinity stress.
We suggest that negative DIF treatment can be used commercially to control
shoot elongation in Lavandula during spring. The ¯ower stimulation observed
under negative DIF and high nutrient concentration was still not enough for
commercial growing as plants grown outside ¯ower very easily. On the other
hand, the increase in ¯owering compared to standard greenhouse conditions was
very promising and may help to identify the factors important for ¯ower initiation
in Lavandula.
3.2. Magnolia soulangiana
In general, plants from the negative DIF treatment were smaller than those
from positive DIF. Both main and side shoots were shorter while the number of
shoots as well as the fresh and dry weight of shoots were lower. It seems that, as
in the case of Lavandula, these results can be attributed to higher night respiration
and lower photosynthesis rates under negative DIF. The growth of roots was
similar in both temperature treatments, however (Table 4). Lengths of fully-grown
internodes number 2, 3, 4, and 5 (counting from the stem base) were lower under
negative DIF but the difference was the most evident for internodes 2, 3 and 4
(Fig. 2). The length of the ®rst internode on the shoot was very low in all
treatments and differences were not statistically signi®cant. The length of
internode number 6 did not differ signi®cantly between temperature treatments at
5% level of signi®cance. Even though negative DIF changes the growth
characteristics of Magnolia soulangiana the effect is, unlike that on Lavandula,
limited to the ®rst stages of growth (except for the ®rst internode on the shoot). A
Table 4
Growth of Magnolia soulangiana under positive and negative DIF regimes and two concentrations
of nutrient solution
DIF
Length of main shoot (cm)
Total length of side shoots (cm)
No. of shoots per plant
Shoot fresh weight (g)
Dry matter content of shoots (%)
Dry weight of roots (g)
Solution concentration
Negative
LSD
Positive
High
LSD
Low
29.0
26.9
2.1
42.4
20.3
2.56
2.9a
6.5a
0.2a
6.2a
0.3a
0.6ns
41.4
43.9
2.4
54.4
20.7
2.77
35.5
37.1
2.4
49.9
20.2
2.58
2.3a
5.3ns
0.2ns
5.1ns
0.2a
0.5ns
38.5
38.2
2.3
51.2
20.5
2.69
a
Differences signi®cant at P < 0.05 level or not signi®cant (ns) according to Student's t-test. No
interaction was signi®cant.
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
119
Fig. 2. Effect of temperature treatment and concentration of nutrient solution on length of
consecutive internodes on main shoot of Magnolia soulangiana grown in greenhouse (error bars
represent S.E. for means).
different action of DIF depending on growth stage was also reported by Sach
(1995). Less pronounced differences between treatments in late spring can also
come from the longer photoperiod stimulating gibberellin biosynthesis which
nulli®es the effect of negative DIF (Moe et al., 1995). Additionally, negative DIF
conditions become dif®cult to obtain during late spring. Thus, the procedure
cannot be seen as an ef®cient tool for reducing ®nal length of internodes
throughout the production cycle during greenhouse cultivation of this species.
However, negative DIF can help to control excessive internode elongation at the
beginning of the growing season (Fig. 2) which can be important when protecting
structures are used only to force plant growth in the spring. Moreover, good root
growth combined with reduced shoot growth can make the acclimation of
greenhouse plants to outside conditions much easier.
High nutrient concentrations reduced the length of the main shoot (Table 4) but
had no effect on length of internodes (Fig. 2). So the reduction of main shoot
length (which was also observed on Pelargonium by Leeuwen (1994)) came in
this treatment exclusively from a lower number of internodes on the shoot which
suggests slower shoot development. However, neither the length of the side shoots
nor the number of shoots were changed (Table 4). Thus, we can conclude that a
high level of nutrients results in somewhat smaller but not much more compact
plants even though main shoot domination is slightly suppressed. A high nutrient
120
M. Bielenin, M.K. Joustra / Scientia Horticulturae 85 (2000) 113±121
concentration also resulted in a lower dry matter content of shoots, while the fresh
weight of shoots as well as the dry weight of roots were unaffected. These suggest
that the nutrient concentrations tested in the experiment fall within the range of
tolerance for Magnolia but they failed to in¯uence the plants' growth pattern
signi®cantly.
4. Conclusions
1. Negative DIF reduces the length of internodes on Lavandula without an
adverse effect on growth.
2. Magnolia grows slower when exposed to negative DIF conditions but changes
in the plant's architecture are limited and the length of internodes is reduced
only at the beginning of the growing season.
3. Negative DIF enhances ¯owering of Lavandula.
4. A higher nutrient concentration reduces growth of both Magnolia and
Lavandula, the latter being much more affected supposedly due to a higher
sensitivity to salinity stress.
Acknowledgements
The experiments were conducted in Research Station for Nursery Stock,
Boskoop, The Netherlands, as a part of the extended research project on the effect
of physical conditions on growth of nursery plants in greenhouse. We would like
to thank J.H.M. Sievierink, for his work on the statistical data analysis as well as
A.J. van Fulpen and M.R. Blanken for their technical assistance.
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