Flower Induction – Hormonal and Substrate Control
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Transcript of Flower Induction – Hormonal and Substrate Control
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.
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
Introduction
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 mid-
august???
Materials and Methods
Experiment 1:
GA spray inhibited flower formation
GA treatment delayed flower differentiation
Results and Discussion
No statistics
Very few flowers
differentiate if GA effect
lasts during the main
induction period
Results and Discussion
No statistics
Experiment 2: No flowering in control and GA treated trees BTOA induced maximum flowering
Results and Discussion
No statistics
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
Results and Discussion
“Leaf symptoms found with GA are well known”
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?
Overview
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
Sweet orange trees – Navelate and Washington navel
No other details were given in materials and methods
Materials and Methods
GA sprays during winter greatly reduced flowering
The effect depends on the concentration and time of application
Results and Discussion
Absolute values
were not
presented
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
Results and Discussion
No statistics shown in figure
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
Overview
Discussion
Davenport. 1983. Daminozide and Gibberellin Effects on Floral Induction of Citrus latifolia.
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
Introduction
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
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
Results and Discussion
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
Overview
Discussion
Garcia-Luis et al. 1986. Inhibition of flowering in vivo by existing fruits and applied growth regulators in Citrus unshiu
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
Introduction
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
Materials and Methods
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
Results and discussion
No statistics
Results and discussion
Influence of time of GA application on spouting
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
Overview
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.)
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
Introduction
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
Materials and Methods
Results and Discussion
IAA and
ABA
contents in
the leaves
Results and Discussion
GA
content in
the leaves
Results and Discussion
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
Overview
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
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
Materials and Methods
Effects on the number of sprouting buds during the spring flush
Results and Discussion
No statistics
Effects on the number of lateral shoots developing
during the spring flush
Results and Discussion
No statistics
Effects on the number of lateral shoots per
sprouting internode during the spring flush
Results and Discussion
No statistics
Effects on the type of new lateral shoots
No significant difference when FUdR or TdR are applied separately
Results and Discussion
No statistics
Effects on flower formation
Results and Discussion
Effects on mitotic activity in the apex during floral
induction and differentiation
Results and Discussion
FUdR is a DNA synthesis inhibitor and it can affect RNA synthesis when it is converted to 5-Fluorouracil
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
Overview
Discussion
Goldschmidt et al. 1985. A Role for Carbohydrate Levels in the Control of Flowering in Citrus.
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
Introduction
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
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
Results and Discussion
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
Overview
Discussion
Monerri and Guardiola. 2001. Peroxidase activity and isoenzyme profile in buds and leaves in relation to flowering in satsuma mandarin.
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
Introduction
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
Materials and Methods
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
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
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
Overview
Discussion