Transcript Flower Induction – Hormonal and Substrate

Flower Induction – Hormonal and
Substrate Control
Karthik-Joseph John
Horticultural Sciences Department
University of Florida
Monselise and Halevy. 1964. Chemical
Inhibition and Promotion of Citrus Flower
Bud Induction.
Introduction
 Gibberellic acid inhibits flower formation in
apples, pears, peaches and many other plants
 First paper to study the effect of GA on citrus
flower induction
 Study the GA effect on citrus and to better
understand the timing of bud induction
 Use of anti-GA or other growth regulators to
induce flowering in lemons as an alternative to
withholding irrigation
Materials and Methods
Experiment 1:
 Shamouti oranges – 1 branch/tree on the
southern part of each tree
 Treatments – 200 ppm of GA sprays for 3, 4, 5 or
6 times at 2-week intervals from November 3
 4 replications per treatment
 Flowers were counted on the branches on April 5
 Sprouting vegetative buds were recorded on
January 1 and February 12
Materials and Methods
Experiment 2:
 Eureka lemons – 2 branches/tree on the
south-eastern side
 Treatments – 2 sprays of 0.2% Cycocel, 0.2%
B Nine, 50ppm BTOA or 500ppm GA
 Flower buds, flowers and fruitlets less than 2
cm in diameter were counted on Nov. 4
 Withhold irrigation for 2 months starting midaugust???
Results and Discussion
Experiment 1:
 GA spray inhibited flower formation
 GA treatment delayed flower differentiation
No statistics
Results and Discussion
 Very few flowers
differentiate if GA effect
lasts during the main
induction period
No statistics
Results and Discussion
Experiment 2:
 No flowering in control and GA treated trees
 BTOA induced maximum flowering
No statistics
Results and Discussion
 Effect of BTOA on citrus
leaves
 Rolling of leaf margins in
leaves of the new growth
produced under the
influence of the chemical
 Formation of flower
clusters at the apex of the
young branches
“Leaf symptoms found with GA are well known”
Overview
 Abstract is missing
 Experimental design is not mentioned
 Only southern part of the tree is used – so
results may not represent the overall effect
 What is the basis for selecting the conc. of GA?
 No statistical analysis
 In experiment 1, data for measurements on Jan
1 is missing
 No details on the leaf symptoms due to GA
 Typing error?
Discussion
Guardiola et al. 1977. Gibberellic acid and
flower bud development in sweet orange.
Introduction
 The inhibitory effect of GA is used to control
alternate bearing
 The mechanism of the inhibitory action is
unknown
Earlier hypothesis:
 GA interferes with flower induction
 GA may reverse flower bud to a vegetative
apex through an indirect mechanism
 A different mechanism of action of GA on
flowering is observed
Materials and Methods
 Sweet orange trees – Navelate and Washington
navel
 No other details were given in materials and
methods
Results and Discussion
 GA sprays during winter greatly reduced
flowering
 The effect depends on the concentration and
time of application
Absolute values
were not
presented
Results and Discussion
 There is decrease in the leafless type of
inflorescences with a parallel increase in the
vegetative shoots
Results and Discussion
 Number of leaves per shoot increased but
there was no change in the number of flowers
Results and Discussion
 Inhibition in flowering is mainly due to decrease
in number of shoots of RF and S types
Results and Discussion
 The buds in the more apical nodes started growth
earlier and in a greater number than in the more
basal
 GA did not affect the proportion of shoots which
abscise during early phases of development
No statistics shown in figure
Overview
 The main effect of GA lies in the inhibition of bud
development
 Insufficient information about the materials and
methods
 Statistical analysis is not show for the figure
 Results and interpretation were difficult to
understand
Discussion
Davenport. 1983. Daminozide and
Gibberellin Effects on Floral Induction of
Citrus latifolia.
Introduction
 Tahiti limes grown in southern Florida are ever
bearing
 Heavy flushes of flowers – Jan., Feb. and March
 Fewer flowers – several times throughout the
year
 Majority of production – summer months
 It is desirable to induce heavy flowering in any
flush to increase off season crop
Materials and Methods
 18 year old Tahiti lime trees
 3 treatments – 0.1mM GA, 2500 ppm daminozide
and distilled water control
 4 replications per treatment
First experiment:
 Treatments applied in mid-August at the onset of
summer flush
 3 sprays in one week period
 Daminozide concentration – 500 ppm
 Total number of new shoot and shoot type were
observed in mid-September
Materials and Methods
Second experiment:
 First spray was done in mid-December, prior to
spring flush
 2 weekly sprays of 500 ppm daminozide followed
by 4 weekly sprays of 1000 ppm
 These were followed by 2500 ppm daminozide
prior to and during the spring flush
 GA and control were applied at all times
Results and Discussion
 The flush was vegetative which is typical for that
time of year
 No tendency to flower in daminozide treatment
 GA increased the number of shoots produced
 The morphology of vegetative shoots in the GA
treatment was comparable to control and
daminozide treatment
Results and Discussion
 GA treatment
shifted shoot
type from
predominantly
flowering to
mainly
vegetative
 Daminozide
inhibited
flowering
Overview
 Materials and methods were not organized
together
 Details of experimental design and statistical
analysis were not mentioned
 The data from the west side of the trees are not
reliable – the western side was crowded due to
closely placed adjacent rows and so there was
shading and also the sprays were unable to
cover completely on this side
Discussion
Garcia-Luis et al. 1986. Inhibition of
flowering in vivo by existing fruits and
applied growth regulators in Citrus unshiu
Introduction
 Flowering in citrus is inversely related to the
previous crop
 This could be due to an interference in the build-
up of reserves and hormonal imbalance
 This study investigates the time course of
flowering inhibition by the fruit
 This effect is compared to the application of GA
 Also studied the effect of kinetin, ABA and 2,4-D
Materials and Methods
 10 year old Owari Satsuma mandarin
 Randomized Block Design with single whole
tree replicates
 5 µL drop of 200 ppm solution of growth
regulator was placed directly on the bud
 Growth regulators GA, ABA, kinetin and 2,4-D
were used
 10 most apical buds from each twig from
previous summer were selected
 20 twigs were selected for each compound
 Application – from middle Dec. to middle Jan.
 Whole tree spray was also done using the
chemicals
Results and discussion
 Only GA reduced the number of sprouted nodes
Results and discussion
 Similar response was obtained when GA and
kinetin were applied to entire tree instead of
locally to the buds
Results and discussion
 Influence of time of GA application on flowering
No statistics
Results and discussion
 Influence of time of GA application on spouting
Overview
 Most data support the work done earlier
 The inhibitory effect of GA and kinetin on bud
sprouting contrasts with the promotive effect
found when applied to non-flowering seedlings
and young trees
 Good experimental design
 Statistics is done but no statistics is shown for
figure 3
Discussion
Koshita et al. 1999. Involvement of
endogenous plant hormones (IAA, ABA,
GAs) in leaves and flower bud formation of
satsuma mandarin (Citrus unshiu Marc.)
Introduction
 This paper investigates the effect of the levels
of endogenous plant hormones in relation to
flowering
 The relation to other plant hormones was not
simultaneously investigated
 The aim of this study is to clarify the
relationship between flower bud formation and
plant hormones (IAA, ABA, GA1/3, GA4/7)
contents
Materials and Methods
 25 year old satsuma mandarin
 8 lateral branches consisting of only vegetative
shoots were chosen in each tree
 4 of them are ringed
 60 fruit bearing shoots are selected in each tree
Results and Discussion
Results and Discussion
 IAA and
ABA
contents in
the leaves
Results and Discussion
 GA
content in
the leaves
Overview
 In October, higher endogenous GA levels may
be one of the reasons for vegetative growth in the
following spring
 In Dec. and Feb. only slight difference was
observed in GA content between bearing and
vegetative shoots – this supports the work of
others
 Increase of leafless inflorescence and
enhancement of ABA in Dec. and Feb. and of IAA
in Dec. suggests that endogenous ABA and IAA
may affect flower bud development
Discussion
Jona et al. 1971. Further Studies on the
Effect of Nucleic Acids on Shoot and
Flower Formation in Citrus Trees.
Introduction
 FUdR is a specific DNA synthesis inhibitor
which promotes flowering in citrus
 This controls flower formation at the stage of
cell division in the growing apex
 This paper deals with the effects of this
chemical on flower and shoot formation
 The role of cell division in flower formation was
studied by applying FUdR and TdR during the
induction and differentiation period
Materials and Methods
 36 year old Shamouti orange trees
 TdR and FUdR were applied either alone or in
combinations at 10-3 M
 Each chemical solution was brushed on leaves,
stem and buds of 10 spring branches beginning
Oct. 17
 Application was repeated at 10 day intervals
 There were 2 series of treatments. In one the
last treatment was applied on Dec. 17 and in
another on Jan. 18
Results and Discussion
 Effects on the number of sprouting buds during
the spring flush
No statistics
Results and Discussion
 Effects on the number of lateral shoots developing
during the spring flush
No statistics
Results and Discussion
 Effects on the number of lateral shoots per
sprouting internode during the spring flush
No statistics
Results and Discussion
 Effects on the type of new lateral shoots
 No significant difference when FUdR or TdR are
applied separately
No statistics
Results and Discussion
 Effects on flower formation
Results and Discussion
 Effects on mitotic activity in the apex during floral
induction and differentiation
Overview
 FUdR is a DNA synthesis inhibitor and it can
affect RNA synthesis when it is converted to 5Fluorouracil
 TdR may counteract the effect of FUdR on DNA
but not on RNA
 So, the inhibition of RNA synthesis is crucial for
the promotion and bud opening
 Thus, FUdR + TdR promotes flower formation by
interfering with RNA metabolism
 No details on experimental design were given
 They have mentioned the use of std. errors and
multiple range test, but they were not shown in
the graphs
Discussion
Goldschmidt et al. 1985. A Role for
Carbohydrate Levels in the Control of
Flowering in Citrus.
Introduction
 Carbohydrate levels have been suggested as a
limiting factor for flower formation in citrus
 In this study, they examined several lines of
evidence for the role of carbohydrates and their
possible interaction with other factors in the
control of flowering
Materials and Methods
 Mature, shy bearing Shamouti orange trees
 Girdling was done in late October
 Half of control and half of girdled trees were
sprayed with 72 µM GA in Nov. and Dec.
 3 year old potted Minneola tangelo were used in
another experiment in which plants are subjected
to various day/night temperatures
Results and Discussion
 Effects of girdling on starch and flowering
 There is correlation between elevated
carbohydrate levels and flowering
Results and Discussion
 Starch contents in leaves and twigs as affected
by GA and girdling
Results and Discussion
 Effect of GA and girdling on shoot type
 GA counteracted the girdling effect
Results and Discussion
 Quantitative effects of cool temperatures on the
promotion of flowering
 Starch levels did not correlate well with flowering
 Intensity of flowering was in accordance with the
exposure to cold temperatures
Overview
 Carbohydrate levels play a role in flower
induction but it is not always the limiting factor
 More details could have been added in the
Materials and Methods section e.g.. Light
intensities used for the experiments
 Experimental design and statistical methods
were not explained in the Materials and Methods.
But statistics is well explained for each table
Discussion
Monerri and Guardiola. 2001. Peroxidase
activity and isoenzyme profile in buds and
leaves in relation to flowering in satsuma
mandarin.
Introduction
 Changes in peroxidase activity and isoenzyme
profiles have been described during flower
induction in other species
 The aim of this work is to determine if the
changes in peroxidase activity and isoenzyme
profiles can be related to the developmental
states of the buds
 They have compared the seasonal changes in
peroxidase activity and isoenzyme pattern in
young flowering and in adult flowering trees
Materials and Methods
 1 year old and 30 year old trees of satsuma
mandarin were used to study seasonal changes
 3 year old potted trees were used to study the
changes during low temperature flower induction
 To study the effect of girdling, adult trees were
girdled by mid-September
Results and discussion
 Fractionation of enzyme activity
Results and discussion
 Isoenzyme patterns of soluble and ionically
bound cell wall peroxidases
Results and discussion
 Changes in fresh weight of buds and leaves
Results and discussion
 Changes in
peroxidase activity
in leaves
 In adult trees, high
peroxidase activities
were mostly
established by Sep.
before the buds
acquired
competence to
flower
Results and discussion
 Isoenzyme patterns in leaves
Results and discussion
 Changes in peroxidase activity in buds
Results and discussion
 Isoenzyme patterns in buds
Results and discussion
 Effect of girdling on peroxidase activity
Results and discussion
 Effect of inductive low temperature conditions
Overview
 Higher peroxidase activities in the leaves from
flowering trees compared to non-flowering trees
could not be related to the flowering process
 Consistent differences in peroxidase activity
related to flowering was not found in the buds
 Girdling had no effect on peroxidase activity
 So, the enzyme fractions and the isoenzyme
patterns are not useful markers for developmental
flowering stages of the buds
 Only one parameter was considered in this paper
Discussion