Directory UMM :Data Elmu:jurnal:S:Scientia Horticulturae:Vol86.Issue1.Sept2000:
Scientia Horticulturae 86 (2000) 57±70
The effects of temperature and daylength on
¯ower initiation and development in Dianthus
allwoodii and Dianthus alpinus
D.C.E. Wurra,*, Jane R. Fellowsa, Lynn Andrewsb
a
Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK
Horticulture Research International, Efford, Lymington, Hampshire SO41 0LZ, UK
b
Accepted 21 December 1999
Abstract
In four experiments the major effect on ¯owering was that of temperature. Temperatures applied
between 2 October and 20 February in¯uenced the time of ¯owering of D. allwoodii, `Doris', while
in D. alpinus, `Pike's Pink', temperatures applied over a longer period between 2 October and 11
March in¯uenced the time of ¯owering. Keeping stock plants at low temperatures, before cuttings
were taken, advanced ¯owering. The earliest ¯owering in `Doris' was achieved by storing stock
plants at 3.98C and then rooting cuttings at 14.98C (rather than at 10.08C) suggesting that it was
possible to satisfy their ¯ower induction requirement entirely during cold storage. In `Pike's Pink'
earliest ¯owering was achieved by storing stock plants at 3.98C and then rooting cuttings at 10.08C,
suggesting that the cold requirement for ¯ower induction was not entirely satis®ed by cold storing
stock plants but in addition needed some time at low temperature during rooting. The cold
requirement of `Pike's Pink' was greater than that of `Doris' and in several treatments was not
satis®ed suf®ciently for ¯owering to occur.
The number of ¯owers in `Doris' was increased by low stock plant temperatures, low
temperatures post-rooting, and higher temperatures during growing on. In `Pike's Pink' number of
¯owers were increased by low stock plant temperatures and low temperatures post-rooting.
# 2000 Elsevier Science B.V. All rights reserved.
Keywords: Temperature; Light intensity; Daylength; Flower initiation
*
Corresponding author. Tel.: 44-1789-470382; fax: 44-1789-470552.
E-mail address: [email protected] (D.C.E. Wurr)
0304-4238/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 0 0 ) 0 0 1 3 1 - X
58
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
1. Introduction
An increasingly competitive market for container nursery stock production
wants plants in ¯ower, at point of sale, over an extended sales period. This
requires the establishment of techniques to produce sequences of quality plants, at
the optimum ¯owering stage, over an extended season. In Dianthus this involves
understanding the roles of daylength, irradiance and temperature in ¯ower
initiation and development.
Modern pinks are probably cultivars of D. allwoodii, a hybrid of D.
caryophyllus and D. plumarius and possibly other species (Cockshull, 1985).
However, knowledge of the physiology of D. allwoodii is very limited and there
appears to be no scienti®c literature concerning D. alpinus. There is some
evidence of daylength effects in the garden pink `Doris'. Plants failed to produce
¯ower buds when grown for 6 months in short days, whereas plants given `duskto-dawn' lighting (long days) from tungsten lamps for 1 month initiated ¯owers
which reached anthesis just over 1 month after the treatment ended (Harris,
1973).
It may be possible to infer some understanding of the physiology from that of
D. caryophyllus, the glasshouse carnation. Certainly in D. caryophyllus there are
effects of daylength, irradiance and temperature on ¯ower initiation (Bunt and
Cockshull, 1985) but only effects of temperature on ¯ower development.
According to Cockshull (1985) many Dianthus species require vernalization but
there is a wide range of responses within the genus Dianthus and sometimes even
within a species.
2. Materials and methods
Four experiments were conducted, studying the effects of daylength, irradiance
and temperature on the ¯owering of D. allwoodii, `Doris' and D. alpinus, `Pike's
Pink'. Temperature regimes are shown in Fig. 1, together with the timescales in
days from 1 January in each year. Effects of treatments applied during three
stages of growth: stock plant maintenance, rooting and post-rooting were studied.
Where controlled environment cabinets were used to apply environmental
treatments, plants were arranged within each cabinet in a blocked structure. This
enabled true replication to be imposed once plants were removed from the
cabinets.
2.1. Experiment 1 1995/1996 Ð effects of temperature post-rooting
Cuttings were taken from stock plants, maintained in pots under cold glass, on
22 June, rooted under mist and potted on into 9 cm pots and the terminal shoots of
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
Fig. 1. Temperature regimes for the four experiments showing time durations and the mean temperatures observed during each phase.
59
60
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
`Doris' were pinched out. Forty-eight plants of each type were put, in four
replicates, into each of four environments in controlled environment cabinets on 2
October for 8 weeks. The effect of continuous temperatures of 6.10.06,
10.10.06, 13.90.04 and 18.10.028C was studied with a daylength of 8 h
given by 30 W mÿ2 PAR ¯uorescent lighting, together with tungsten lamps at
2 W mÿ2 PAR. This lighting regime was chosen because its daily light integral
most closely represented that occurring during December and January in the UK.
Samples of ®ve plants of each type were taken on 3 October, 30 October and 13
November and dissected under a binocular microscope. Plants were cut off at the
lowest pair of leaves or leaf scars and the state of the apex was recorded. On 27
November the plants were moved onto ebb and ¯ow benches in a ventilated
polyethylene tunnel with an average temperature of 9.20.398C until ¯owering
was complete. Further samples were taken on 27 November, 19 December, 22
January, 4 March, 10 April, 26 April and 14 May. Flowers were tagged as they
opened and the total number of ¯owers and the height of stems were recorded on
all plants.
2.2. Experiment 2 1996 Ð effects of temperature during rooting and temperature
and daylength post-rooting
This experiment and the two following imposed different temperature regimes
using a combination of semi-commercial and experimental conditions. Cuttings
were taken from stock plants on 29 October and rooted under mist at slightly
different air temperatures: means of 9.80.27 and 11.30.298C. Resulting plants
were then grown for 8 weeks in controlled environment cabinets from 15 January.
There were four replicates of six plants receiving all combinations of two
temperatures: 10.00.01 and 18.00.018C and two daylengths: 12 and 15 h,
under the same irradiance conditions as in experiment 1. Plants were then moved
to a ventilated polyethylene tunnel on 11 March. Flower development was
recorded as previously and the average temperature over the whole period in the
polyethylene tunnel was 12.60.468C.
2.3. Experiment 3 1996/1997 Ð effects of temperature during stock plant
maintenance and rooting
The effects of temperature on one-year-old stock plants and the cuttings taken
from them during rooting and post-rooting were explored further. In the 5 weeks
up to 7 November stock plants were exposed to cold temperatures (3.90.018C)
in an unlit cold store; ambient temperatures (13.40.288C) in an unheated clear
polyethylene tunnel or warm temperatures (16.30.168C) in a heated glasshouse
before cuttings were taken as previously described. Then mean continuous
temperatures of 10.00.20 or 14.90.008C, combined with a 16 h daylength
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
61
given by high pressure sodium lamps at 16 W mÿ2 PAR, were applied during
rooting from 7 November to 15 January. On 20 January 32 plants of each type and
treatment were put in four replicate controlled environment cabinets at
10.00.018C under a 12 h daylength with irradiance as in experiments 1 and
2. Eight plants of each treatment went into each cabinet. Samples of three plants
per treatment were taken for dissection on 20 January. Plants were moved to a
ventilated clear polyethylene tunnel on 17 March. Flower development was
recorded as previously and the average temperature in the polyethylene tunnel
over the whole period was 15.60.338C.
2.4. Experiment 4 1997 Ð effects of temperature during stock plant maintenance,
rooting and post-rooting
This was designed to extend the ideas developed from the previous three
experiments. There were two replicates of four stock plant environments, two
rooting temperatures and two temperatures post-rooting. Stock plants of both
`Doris' and `Pike's Pink', which had previously been kept at the high temperature
(16.30.168C) in experiment 3, were used. They were either kept warm for 36
days, starting from 15 January, or transferred to an unlit cold store at 4.80.078C
for 36, 24 or 12 days, before cuttings were taken after 36 days. These were then
rooted `warm' (14.90.158C) or `cool' (13.10.208C) from 21 February to 3
April and grown post-rooting at two temperatures from 25 April until the
experiment was terminated on 31 August. A ventilated polyethylene tunnel
(15.80.338C) and a cooled glasshouse compartment (13.00.198C) were used
to give a mean temperature difference of 2.88C. Flower development was
recorded as before.
2.5. Data analysis
Data were subjected to analysis of variance. For all experiments the two
cultivars were analysed separately and the tables present results where there are
signi®cant differences at p
The effects of temperature and daylength on
¯ower initiation and development in Dianthus
allwoodii and Dianthus alpinus
D.C.E. Wurra,*, Jane R. Fellowsa, Lynn Andrewsb
a
Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK
Horticulture Research International, Efford, Lymington, Hampshire SO41 0LZ, UK
b
Accepted 21 December 1999
Abstract
In four experiments the major effect on ¯owering was that of temperature. Temperatures applied
between 2 October and 20 February in¯uenced the time of ¯owering of D. allwoodii, `Doris', while
in D. alpinus, `Pike's Pink', temperatures applied over a longer period between 2 October and 11
March in¯uenced the time of ¯owering. Keeping stock plants at low temperatures, before cuttings
were taken, advanced ¯owering. The earliest ¯owering in `Doris' was achieved by storing stock
plants at 3.98C and then rooting cuttings at 14.98C (rather than at 10.08C) suggesting that it was
possible to satisfy their ¯ower induction requirement entirely during cold storage. In `Pike's Pink'
earliest ¯owering was achieved by storing stock plants at 3.98C and then rooting cuttings at 10.08C,
suggesting that the cold requirement for ¯ower induction was not entirely satis®ed by cold storing
stock plants but in addition needed some time at low temperature during rooting. The cold
requirement of `Pike's Pink' was greater than that of `Doris' and in several treatments was not
satis®ed suf®ciently for ¯owering to occur.
The number of ¯owers in `Doris' was increased by low stock plant temperatures, low
temperatures post-rooting, and higher temperatures during growing on. In `Pike's Pink' number of
¯owers were increased by low stock plant temperatures and low temperatures post-rooting.
# 2000 Elsevier Science B.V. All rights reserved.
Keywords: Temperature; Light intensity; Daylength; Flower initiation
*
Corresponding author. Tel.: 44-1789-470382; fax: 44-1789-470552.
E-mail address: [email protected] (D.C.E. Wurr)
0304-4238/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 0 0 ) 0 0 1 3 1 - X
58
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
1. Introduction
An increasingly competitive market for container nursery stock production
wants plants in ¯ower, at point of sale, over an extended sales period. This
requires the establishment of techniques to produce sequences of quality plants, at
the optimum ¯owering stage, over an extended season. In Dianthus this involves
understanding the roles of daylength, irradiance and temperature in ¯ower
initiation and development.
Modern pinks are probably cultivars of D. allwoodii, a hybrid of D.
caryophyllus and D. plumarius and possibly other species (Cockshull, 1985).
However, knowledge of the physiology of D. allwoodii is very limited and there
appears to be no scienti®c literature concerning D. alpinus. There is some
evidence of daylength effects in the garden pink `Doris'. Plants failed to produce
¯ower buds when grown for 6 months in short days, whereas plants given `duskto-dawn' lighting (long days) from tungsten lamps for 1 month initiated ¯owers
which reached anthesis just over 1 month after the treatment ended (Harris,
1973).
It may be possible to infer some understanding of the physiology from that of
D. caryophyllus, the glasshouse carnation. Certainly in D. caryophyllus there are
effects of daylength, irradiance and temperature on ¯ower initiation (Bunt and
Cockshull, 1985) but only effects of temperature on ¯ower development.
According to Cockshull (1985) many Dianthus species require vernalization but
there is a wide range of responses within the genus Dianthus and sometimes even
within a species.
2. Materials and methods
Four experiments were conducted, studying the effects of daylength, irradiance
and temperature on the ¯owering of D. allwoodii, `Doris' and D. alpinus, `Pike's
Pink'. Temperature regimes are shown in Fig. 1, together with the timescales in
days from 1 January in each year. Effects of treatments applied during three
stages of growth: stock plant maintenance, rooting and post-rooting were studied.
Where controlled environment cabinets were used to apply environmental
treatments, plants were arranged within each cabinet in a blocked structure. This
enabled true replication to be imposed once plants were removed from the
cabinets.
2.1. Experiment 1 1995/1996 Ð effects of temperature post-rooting
Cuttings were taken from stock plants, maintained in pots under cold glass, on
22 June, rooted under mist and potted on into 9 cm pots and the terminal shoots of
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
Fig. 1. Temperature regimes for the four experiments showing time durations and the mean temperatures observed during each phase.
59
60
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
`Doris' were pinched out. Forty-eight plants of each type were put, in four
replicates, into each of four environments in controlled environment cabinets on 2
October for 8 weeks. The effect of continuous temperatures of 6.10.06,
10.10.06, 13.90.04 and 18.10.028C was studied with a daylength of 8 h
given by 30 W mÿ2 PAR ¯uorescent lighting, together with tungsten lamps at
2 W mÿ2 PAR. This lighting regime was chosen because its daily light integral
most closely represented that occurring during December and January in the UK.
Samples of ®ve plants of each type were taken on 3 October, 30 October and 13
November and dissected under a binocular microscope. Plants were cut off at the
lowest pair of leaves or leaf scars and the state of the apex was recorded. On 27
November the plants were moved onto ebb and ¯ow benches in a ventilated
polyethylene tunnel with an average temperature of 9.20.398C until ¯owering
was complete. Further samples were taken on 27 November, 19 December, 22
January, 4 March, 10 April, 26 April and 14 May. Flowers were tagged as they
opened and the total number of ¯owers and the height of stems were recorded on
all plants.
2.2. Experiment 2 1996 Ð effects of temperature during rooting and temperature
and daylength post-rooting
This experiment and the two following imposed different temperature regimes
using a combination of semi-commercial and experimental conditions. Cuttings
were taken from stock plants on 29 October and rooted under mist at slightly
different air temperatures: means of 9.80.27 and 11.30.298C. Resulting plants
were then grown for 8 weeks in controlled environment cabinets from 15 January.
There were four replicates of six plants receiving all combinations of two
temperatures: 10.00.01 and 18.00.018C and two daylengths: 12 and 15 h,
under the same irradiance conditions as in experiment 1. Plants were then moved
to a ventilated polyethylene tunnel on 11 March. Flower development was
recorded as previously and the average temperature over the whole period in the
polyethylene tunnel was 12.60.468C.
2.3. Experiment 3 1996/1997 Ð effects of temperature during stock plant
maintenance and rooting
The effects of temperature on one-year-old stock plants and the cuttings taken
from them during rooting and post-rooting were explored further. In the 5 weeks
up to 7 November stock plants were exposed to cold temperatures (3.90.018C)
in an unlit cold store; ambient temperatures (13.40.288C) in an unheated clear
polyethylene tunnel or warm temperatures (16.30.168C) in a heated glasshouse
before cuttings were taken as previously described. Then mean continuous
temperatures of 10.00.20 or 14.90.008C, combined with a 16 h daylength
D.C.E. Wurr et al. / Scientia Horticulturae 86 (2000) 57±70
61
given by high pressure sodium lamps at 16 W mÿ2 PAR, were applied during
rooting from 7 November to 15 January. On 20 January 32 plants of each type and
treatment were put in four replicate controlled environment cabinets at
10.00.018C under a 12 h daylength with irradiance as in experiments 1 and
2. Eight plants of each treatment went into each cabinet. Samples of three plants
per treatment were taken for dissection on 20 January. Plants were moved to a
ventilated clear polyethylene tunnel on 17 March. Flower development was
recorded as previously and the average temperature in the polyethylene tunnel
over the whole period was 15.60.338C.
2.4. Experiment 4 1997 Ð effects of temperature during stock plant maintenance,
rooting and post-rooting
This was designed to extend the ideas developed from the previous three
experiments. There were two replicates of four stock plant environments, two
rooting temperatures and two temperatures post-rooting. Stock plants of both
`Doris' and `Pike's Pink', which had previously been kept at the high temperature
(16.30.168C) in experiment 3, were used. They were either kept warm for 36
days, starting from 15 January, or transferred to an unlit cold store at 4.80.078C
for 36, 24 or 12 days, before cuttings were taken after 36 days. These were then
rooted `warm' (14.90.158C) or `cool' (13.10.208C) from 21 February to 3
April and grown post-rooting at two temperatures from 25 April until the
experiment was terminated on 31 August. A ventilated polyethylene tunnel
(15.80.338C) and a cooled glasshouse compartment (13.00.198C) were used
to give a mean temperature difference of 2.88C. Flower development was
recorded as before.
2.5. Data analysis
Data were subjected to analysis of variance. For all experiments the two
cultivars were analysed separately and the tables present results where there are
signi®cant differences at p