Presentation on theme: "Flower Induction – Hormonal and Substrate Control"— Presentation transcript:
1 Flower Induction – Hormonal and Substrate Control Karthik-Joseph JohnHorticultural Sciences DepartmentUniversity of Florida
2 Monselise and Halevy. 1964. Chemical Inhibition and Promotion of Citrus Flower Bud Induction.
3 IntroductionGibberellic acid inhibits flower formation in apples, pears, peaches and many other plantsFirst paper to study the effect of GA on citrus flower inductionStudy the GA effect on citrus and to better understand the timing of bud inductionUse of anti-GA or other growth regulators to induce flowering in lemons as an alternative to withholding irrigation
4 Materials and Methods Experiment 1: Shamouti oranges – 1 branch/tree on the southern part of each treeTreatments – 200 ppm of GA sprays for 3, 4, 5 or 6 times at 2-week intervals from November 34 replications per treatmentFlowers were counted on the branches on April 5Sprouting vegetative buds were recorded on January 1 and February 12
5 Materials and Methods Experiment 2: Eureka lemons – 2 branches/tree on the south-eastern sideTreatments – 2 sprays of 0.2% Cycocel, 0.2% B Nine, 50ppm BTOA or 500ppm GAFlower buds, flowers and fruitlets less than 2 cm in diameter were counted on Nov. 4Withhold irrigation for 2 months starting mid-august???
7 Results and Discussion Very few flowers differentiate if GA effect lasts during the main induction periodNo statistics
8 Results and Discussion Experiment 2:No flowering in control and GA treated treesBTOA induced maximum floweringNo statistics
9 Results and Discussion Effect of BTOA on citrus leavesRolling of leaf margins in leaves of the new growth produced under the influence of the chemicalFormation of flower clusters at the apex of the young branches“Leaf symptoms found with GA are well known”
10 Overview Abstract is missing Experimental design is not mentioned Only southern part of the tree is used – so results may not represent the overall effectWhat is the basis for selecting the conc. of GA?No statistical analysisIn experiment 1, data for measurements on Jan 1 is missingNo details on the leaf symptoms due to GATyping error?
12 Guardiola et al. 1977. Gibberellic acid and flower bud development in sweet orange.
13 IntroductionThe inhibitory effect of GA is used to control alternate bearingThe mechanism of the inhibitory action is unknownEarlier hypothesis:GA interferes with flower inductionGA may reverse flower bud to a vegetative apex through an indirect mechanismA different mechanism of action of GA on flowering is observed
14 Materials and MethodsSweet orange trees – Navelate and Washington navelNo other details were given in materials and methods
15 Results and Discussion GA sprays during winter greatly reduced floweringThe effect depends on the concentration and time of applicationAbsolute values were not presented
16 Results and Discussion There is decrease in the leafless type of inflorescences with a parallel increase in the vegetative shoots
17 Results and Discussion Number of leaves per shoot increased but there was no change in the number of flowers
18 Results and Discussion Inhibition in flowering is mainly due to decrease in number of shoots of RF and S types
19 Results and Discussion The buds in the more apical nodes started growth earlier and in a greater number than in the more basalGA did not affect the proportion of shoots which abscise during early phases of developmentNo statistics shown in figure
20 OverviewThe main effect of GA lies in the inhibition of bud developmentInsufficient information about the materials and methodsStatistical analysis is not show for the figureResults and interpretation were difficult to understand
22 Davenport. 1983. Daminozide and Gibberellin Effects on Floral Induction of Citrus latifolia.
23 Introduction Tahiti limes grown in southern Florida are ever bearing Heavy flushes of flowers – Jan., Feb. and MarchFewer flowers – several times throughout the yearMajority of production – summer monthsIt is desirable to induce heavy flowering in any flush to increase off season crop
24 Materials and Methods 18 year old Tahiti lime trees 3 treatments – 0.1mM GA, 2500 ppm daminozide and distilled water control4 replications per treatmentFirst experiment:Treatments applied in mid-August at the onset of summer flush3 sprays in one week periodDaminozide concentration – 500 ppmTotal number of new shoot and shoot type were observed in mid-September
25 Materials and Methods Second experiment: First spray was done in mid-December, prior to spring flush2 weekly sprays of 500 ppm daminozide followed by 4 weekly sprays of 1000 ppmThese were followed by 2500 ppm daminozide prior to and during the spring flushGA and control were applied at all times
26 Results and Discussion The flush was vegetative which is typical for that time of yearNo tendency to flower in daminozide treatmentGA increased the number of shoots producedThe morphology of vegetative shoots in the GA treatment was comparable to control and daminozide treatment
27 Results and Discussion GA treatment shifted shoot type from predominantly flowering to mainly vegetativeDaminozide inhibited flowering
28 Overview Materials and methods were not organized together Details of experimental design and statistical analysis were not mentionedThe 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
30 Garcia-Luis et al Inhibition of flowering in vivo by existing fruits and applied growth regulators in Citrus unshiu
31 IntroductionFlowering in citrus is inversely related to the previous cropThis could be due to an interference in the build-up of reserves and hormonal imbalanceThis study investigates the time course of flowering inhibition by the fruitThis effect is compared to the application of GAAlso studied the effect of kinetin, ABA and 2,4-D
32 Materials and Methods 10 year old Owari Satsuma mandarin Randomized Block Design with single whole tree replicates5 µL drop of 200 ppm solution of growth regulator was placed directly on the budGrowth regulators GA, ABA, kinetin and 2,4-D were used10 most apical buds from each twig from previous summer were selected20 twigs were selected for each compoundApplication – from middle Dec. to middle Jan.Whole tree spray was also done using the chemicals
33 Results and discussion Only GA reduced the number of sprouted nodes
34 Results and discussion Similar response was obtained when GA and kinetin were applied to entire tree instead of locally to the buds
35 Results and discussion Influence of time of GA application on floweringNo statistics
36 Results and discussion Influence of time of GA application on spouting
37 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 treesGood experimental designStatistics is done but no statistics is shown for figure 3
39 Koshita et al Involvement of endogenous plant hormones (IAA, ABA, GAs) in leaves and flower bud formation of satsuma mandarin (Citrus unshiu Marc.)
40 IntroductionThis paper investigates the effect of the levels of endogenous plant hormones in relation to floweringThe relation to other plant hormones was not simultaneously investigatedThe aim of this study is to clarify the relationship between flower bud formation and plant hormones (IAA, ABA, GA1/3, GA4/7) contents
41 Materials and Methods 25 year old satsuma mandarin 8 lateral branches consisting of only vegetative shoots were chosen in each tree4 of them are ringed60 fruit bearing shoots are selected in each tree
43 Results and Discussion IAA and ABA contents in the leaves
44 Results and Discussion GA content in the leaves
45 OverviewIn October, higher endogenous GA levels may be one of the reasons for vegetative growth in the following springIn Dec. and Feb. only slight difference was observed in GA content between bearing and vegetative shoots – this supports the work of othersIncrease 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
47 Jona et al Further Studies on the Effect of Nucleic Acids on Shoot and Flower Formation in Citrus Trees.
48 IntroductionFUdR is a specific DNA synthesis inhibitor which promotes flowering in citrusThis controls flower formation at the stage of cell division in the growing apexThis paper deals with the effects of this chemical on flower and shoot formationThe role of cell division in flower formation was studied by applying FUdR and TdR during the induction and differentiation period
49 Materials and Methods 36 year old Shamouti orange trees TdR and FUdR were applied either alone or in combinations at 10-3 MEach chemical solution was brushed on leaves, stem and buds of 10 spring branches beginning Oct. 17Application was repeated at 10 day intervalsThere were 2 series of treatments. In one the last treatment was applied on Dec. 17 and in another on Jan. 18
50 Results and Discussion Effects on the number of sprouting buds during the spring flushNo statistics
51 Results and Discussion Effects on the number of lateral shoots developing during the spring flushNo statistics
52 Results and Discussion Effects on the number of lateral shoots per sprouting internode during the spring flushNo statistics
53 Results and Discussion Effects on the type of new lateral shootsNo significant difference when FUdR or TdR are applied separatelyNo statistics
54 Results and Discussion Effects on flower formation
55 Results and Discussion Effects on mitotic activity in the apex during floral induction and differentiation
56 OverviewFUdR is a DNA synthesis inhibitor and it can affect RNA synthesis when it is converted to 5-FluorouracilTdR may counteract the effect of FUdR on DNA but not on RNASo, the inhibition of RNA synthesis is crucial for the promotion and bud openingThus, FUdR + TdR promotes flower formation by interfering with RNA metabolismNo details on experimental design were givenThey have mentioned the use of std. errors and multiple range test, but they were not shown in the graphs
58 Goldschmidt et al. 1985. A Role for Carbohydrate Levels in the Control of Flowering in Citrus.
59 IntroductionCarbohydrate levels have been suggested as a limiting factor for flower formation in citrusIn 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
60 Materials and Methods Mature, shy bearing Shamouti orange trees Girdling was done in late OctoberHalf 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
61 Results and Discussion Effects of girdling on starch and floweringThere is correlation between elevated carbohydrate levels and flowering
62 Results and Discussion Starch contents in leaves and twigs as affected by GA and girdling
63 Results and Discussion Effect of GA and girdling on shoot typeGA counteracted the girdling effect
64 Results and Discussion Quantitative effects of cool temperatures on the promotion of floweringStarch levels did not correlate well with floweringIntensity of flowering was in accordance with the exposure to cold temperatures
65 OverviewCarbohydrate levels play a role in flower induction but it is not always the limiting factorMore details could have been added in the Materials and Methods section e.g.. Light intensities used for the experimentsExperimental design and statistical methods were not explained in the Materials and Methods. But statistics is well explained for each table
67 Monerri and Guardiola Peroxidase activity and isoenzyme profile in buds and leaves in relation to flowering in satsuma mandarin.
68 IntroductionChanges in peroxidase activity and isoenzyme profiles have been described during flower induction in other speciesThe 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 budsThey have compared the seasonal changes in peroxidase activity and isoenzyme pattern in young flowering and in adult flowering trees
69 Materials and Methods1 year old and 30 year old trees of satsuma mandarin were used to study seasonal changes3 year old potted trees were used to study the changes during low temperature flower inductionTo study the effect of girdling, adult trees were girdled by mid-September
70 Results and discussion Fractionation of enzyme activity
71 Results and discussion Isoenzyme patterns of soluble and ionically bound cell wall peroxidases
72 Results and discussion Changes in fresh weight of buds and leaves
73 Results and discussion Changes in peroxidase activity in leavesIn adult trees, high peroxidase activities were mostly established by Sep. before the buds acquired competence to flower
74 Results and discussion Isoenzyme patterns in leaves
75 Results and discussion Changes in peroxidase activity in buds
76 Results and discussion Isoenzyme patterns in buds
77 Results and discussion Effect of girdling on peroxidase activity
78 Results and discussion Effect of inductive low temperature conditions
79 OverviewHigher peroxidase activities in the leaves from flowering trees compared to non-flowering trees could not be related to the flowering processConsistent differences in peroxidase activity related to flowering was not found in the budsGirdling had no effect on peroxidase activitySo, the enzyme fractions and the isoenzyme patterns are not useful markers for developmental flowering stages of the budsOnly one parameter was considered in this paper
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