Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative process in Douglas-fir. II. Effects on shoot elongation and its relationship to flowering

1985 ◽  
Vol 15 (2) ◽  
pp. 348-353 ◽  
Author(s):  
J. E. Webber ◽  
S. D. Ross ◽  
R. P. Pharis ◽  
J. N. Owens
Keyword(s):  
Synergistic Effect ◽  
Vegetative Growth ◽  
Shoot Growth ◽  
Shoot Elongation ◽  
Douglas Fir ◽  
Threshold Concentration ◽  
Root Pruning ◽  
Flowering Response ◽  
Seed Cone ◽  
Female Flowering

Shoot elongation and female flowering response were assessed for gibberellin A4/7 (GA4/7) and root-pruning (RP) treatments in 9- and 10-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings of families with good- and poor-flowering histories. In families with a poor-flowering history, stem injections of GA4/7 significantly enhanced elongation of third-whorl terminal shoots but produced no flowering response. In families with a good-flowering history, GA4/7 treatment had no effect on shoot elongation but did result in a significant increase in seed-cone buds. In contrast, root-pruning significantly retarded shoot growth in families with both good- and poor-flowering histories and was also the single most effective treatment for enhancing flowering. Combined, GA4/7 plus RP had a synergistic effect on flowering and GA4/7 partially overcame the inhibition of shoot growth caused by RP alone. These results are consistent with a hypothesis that exogenous and endogenous gibberellins are used preferentially for vegetative growth processes, with increased flowering occurring only after a threshold concentration of effector gibberellins is reached.

Promotion of flowering in potted white spruce grafts by root pruning: its relationship to drought and shoot elongation

1991 ◽  
Vol 21 (5) ◽  
pp. 680-685 ◽  
Author(s):  
Stephen D. Ross
Keyword(s):  
Early Stage ◽  
White Spruce ◽  
Shoot Elongation ◽  
Threshold Level ◽  
Response To Treatment ◽  
Root Pruning ◽  
Flowering Response ◽  
Stress Effects ◽  
Female Flowering ◽  
Vegetative Bud

Flowering and shoot-elongation responses by potted white spruce (Piceaglauca (Moench) Voss) grafts to root pruning (RP) and drought, and to RP applied at different stages of root and shoot development, were investigated in separate experiments. Results suggest that RP does not simulate drought. Differences in midday needle water potentials between RP and non RP grafts were relatively small (0.1–0.2 MPa) and short lived following treatment. Furthermore, whereas RP only affected (promoted) female flowering, drought only affected (inhibited) male flowering. Shoot elongation was less inhibited by RP at initiation of new root growth in spring, compared with RP at the late vegetative bud swell stage and at the early stage of rapid shoot elongation, when root activity is naturally declining. However, the flowering response was independent of time of RP. The early RP treatment enhanced shoot elongation in some clones and inhibited it in others, and the effect was not related to the clone's flowering response to treatment. These results are discussed in relation to the hypothesis that in small, potted trees, at least, actively growing roots are an important source of certain gibberellins that are essential for both shoot elongation and cone-bud differentiation. Accordingly, RP may inhibit or enhance shoot elongation, depending on whether the supply of gibberellins from roots newly regenerated following RP exceeds that from existing roots removed in treatment. Flowering occurs when the supply of gibberellins exceeds some threshold level either because of reduced vegetative demand (due to water-stress effects) or increased synthesis by roots.

Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative processes in Douglas-fir. IV. Effects on lateral bud development

1986 ◽  
Vol 16 (2) ◽  
pp. 211-221 ◽  
Author(s):  
J. N. Owens ◽  
J. E. Webber ◽  
S. D. Ross ◽  
R. P. Pharis
Keyword(s):  
Normal Development ◽  
Shoot Elongation ◽  
Douglas Fir ◽  
Root Pruning ◽  
Lateral Shoot ◽  
Bud Development ◽  
Lateral Bud ◽  
Mitotic Frequency ◽  
Bud Initiation ◽  
Vegetative Bud

The anatomy, mitotic frequency, size, and total insoluble carbohydrate histochemistry was studied in axillary apices from 9- and 10-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees after cone induction treatments of root-pruning and (or) stem injections of a gibberellin A4 and A7 (GA4/7) mixture. Axillary buds were initiated at the time of root-pruning, but root-pruning treatment had no effect on axillary bud initiation. Axillary apices from control and gibberellin-treated trees were similar and followed the normal sequence of bud-scale initiation, differentiation, and leaf initiation (described previously) and no cone buds differentiated. Early development of axillary apices from root-pruned and root-pruned, gibberellin-treated trees was normal, but development became retarded near the time of vegetative bud flush. Retarded apices were small with low mitotic frequency and developed many features characteristics of latent apices. Retardation of axillary apices continued until mid-July when normal development resumed and apices differentiated into reproductive buds or vegetative buds, or became latent. The trees in which the greatest retardation of apical development occurred during lateral shoot elongation produced the most cone buds. These results are discussed in relation to hypotheses proposed to explain how cultural and gibberellin treatments affect cone induction in the Pinaceae.

Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative processes in Douglas-fir. III. Effects on anatomy of shoot elongation and terminal bud development

1985 ◽  
Vol 15 (2) ◽  
pp. 354-364 ◽  
Author(s):  
J. N. Owens ◽  
J. E. Webber ◽  
S. D. Ross ◽  
R. P. Pharis
Keyword(s):  
Shoot Elongation ◽  
Douglas Fir ◽  
Apical Growth ◽  
Root Pruning ◽  
Bud Development ◽  
Leaf Initiation ◽  
Terminal Bud ◽  
Terminal Buds ◽  
Effective Cone ◽  
Vegetative Bud

The relative importance of cell division and cell elongation to shoot elongation and the anatomical changes in vegetative terminal apices were assessed for 9- and 10-year-old seedlings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in response to two effective cone-induction treatments, gibberellin A4/7 (GA4/7) and root-pruning (RP). Root-pruning was done in mid-April at the start of vegetative bud swelling and GA treatments were begun at vegetative bud flushing in mid-May and continued until early July. Shoot elongation before flushing resulted primarily from cell divisions and was not affected by the RP treatment. Shoot elongation after flushing resulted primarily from cell expansion which was reduced by RP treatments. Root-pruning significantly slowed mitotic activity, apical growth, and development of vegetative terminal buds from mid-June through mid-July. Apical growth then resumed during leaf initiation and the final number of leaf primordia initiated was not affected. This resulted in a delay of 2 to 4 weeks in the transition from bud-scale to leaf initiation. Retarded terminal vegetative apices anatomically resembled latent axillary apices but were never completely inhibited. GA + RP had the same effect as RP. GA4/7 alone had no effect on shoot or apical development. These results show that RP and GA + RP significantly retard shoot elongation and terminal bud development but still allow normal development of vegetative terminal buds. Retardation of bud development by a few weeks shifts the critical morphogenetic phase of transition from bud scale to leaf initiation to a later time when endogenous and environmental conditions may differ from the normal.

scholarly journals EFFECT OF ROOT PRUNING ON WATER RELATIONS AND SHOOT GROWTH OF `BELLAIRE' PEACH.

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 748A-748
Author(s):  
Roberto Santos ◽  
Bradley H. Taylor ◽  
Roger Kjelgren
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Relations ◽  
Shoot Growth ◽  
Stomatal Closure ◽  
Shoot Elongation ◽  
Root Pruning ◽  
Diurnal Pattern ◽  
June July ◽  
Old Trees

The effect of root pruning on shoot length and water relations of `Bellaire' peach was investigated as a means of controlling vegetative growth. On 27 April, 25 May, and 23 June, 1990, five-year-old trees were root pruned to a 0.35 m depth at either 0.4 or 0.8 m from the tree trunks along both sides of the row. Shoot growth was measured biweekly through the growing season, and the diurnal pattern of stomatal conductance and water potential was followed in late June, July, and August. Stomatal conductance of the root-pruned treatments was less than the control, while there were no differences in water potential among treatments. Reduced shoot elongation was evident within a month of root pruning at 0.4 m for all timing treatments, but at 0.8 m it varied with the date of pruning. The first root pruning at 0.4 m reduced cumulative shoot elongation 39% compared to the un-pruned control trees, while the remaining treatments reduced it 14%. While root pruning limited cumulative shoot elongation in all treatments, the earliest 0.4 m treatment was most effective, possibly due to pruning of a larger percent of the root system prior to rapid shoot elongation. Stomatal closure in root-pruned trees appeared to moderate diurnal water deficits at levels similar to the control.

Promotion of flowering in young Larixlaricina grafts by gibberellin A4/7 and root pruning

1990 ◽  
Vol 20 (9) ◽  
pp. 1448-1452 ◽  
Author(s):  
Throstur Eysteinsson ◽  
Michael S. Greenwood
Keyword(s):  
Plant Growth ◽  
Growth Regulator ◽  
Plant Growth Regulator ◽  
Shoot Elongation ◽  
Root Pruning ◽  
Mature Trees ◽  
Foliar Sprays ◽  
Female Flowering

Flowering was promoted on potted, indoor, and field-grown 3-year-old juvenile and mature Larixlaricina (Du Roi) K. Koch grafts by foliar sprays of the plant-growth regulator gibberellin A4/7 and root pruning. Biweekly gibberellin A4/7 applications of three different durations, commencing at the start of long-shoot elongation, yielded similar increases in female flowering in the greenhouse; this effect was synergistically enhanced by root pruning. Male flowering was promoted by gibberellin A4/7 + root pruning in mature but not juvenile grafts. In the field, female flowering was also promoted by the gibberellin A4/7 treatment commencing at the start of shoot extension, but gibberellin A4/7 applications starting later were not effective. Grafted scions from mature trees responded significantly better to gibberellin A4/7 + root pruning than did seedling scions.

Enhancement of shoot elongation in Douglas-fir by gibberellin A4/7 and its relation to the hormonal promotion of flowering

1983 ◽  
Vol 13 (5) ◽  
pp. 986-994 ◽  
Author(s):  
Stephen D. Ross
Keyword(s):  
Stem Elongation ◽  
Maximum Growth ◽  
Shoot Elongation ◽  
Early Spring ◽  
Douglas Fir ◽  
Threshold Concentration ◽  
Physiological Age ◽  
Growth Enhancement ◽  
Bud Burst ◽  
Treatment Timing

The enhanced stem elongation that frequently accompanies the gibberellin A4/7 (GA4/7) promotion of flowering in Pinaceae species was investigated for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) vegetative propagules in relation to their physiological age, GA4/7 concentration, and treatment timing. Maximum growth enhancement, but marginal promotion of flowering (males and females), occurred when GA4/7 was applied in early spring before vegetative buds had begun to swell. In contrast, shoot elongation was only slightly enhanced when GA4/7 treatment was timed (vegetative bud burst ±4.5 weeks) to bracket the critical period for effecting differentiation of axillary primordia into cone buds. Also, the GA4/7 concentration optimal for flowering was supraoptimal for shoot elongation, and the growth response to GA4/7 decreased, whereas the flowering response increased, with increasing physiological age of the propagules (scions 4–45 years old). These findings are consistent with a hypothesis that exogenous GA4/7 is first utilized for vegetative growth processes, increased flowering occurring only after a threshold concentration is reached.

scholarly journals 225 Prohexadione-Ca: Reduction in Vegetative Growth and Pruning of Apple Trees

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 481A-481 ◽  
Author(s):  
J.R. Evans ◽  
J.A. Balles ◽  
B.A. Brinkman ◽  
V.E. Harris ◽  
J.D. Helm ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Shoot Growth ◽  
Shoot Elongation ◽  
Application Rate ◽  
Growth Reduction ◽  
Apple Trees ◽  
Positive Effects ◽  
Enhanced Resistance ◽  
Prohexadione Calcium ◽  
Made In

Prohexadione-Ca (BAS 12511W or Apogee™ Plant Growth Regulator) acts within a plant by blocking the biosynthesis of growth-active gibberellin. The result is decreased cell and shoot elongation; thus, vegetative growth in apple trees can be reduced. Air blast applications of prohexadione calcium were made in the Spring 1998 in commercial orchards. Application rate was 125 ppm a.i. applied twice beginning at 5 to 12 cm of new shoot growth. Reduction of shoot growth averaged 45% across locations. As a result of reduced vegetative growth, dormant pruning was reduced. In total, significant benefits to the grower included reduced pruning costs in addition to other positive effects such as improved light penetration and enhanced resistance to some pathogens. Research will continue with the effect of prohexadione-Ca on pruning in multiple year studies.

Gibberellins and sorghum development

1988 ◽  
Vol 66 (6) ◽  
pp. 1101-1106 ◽  
Author(s):  
Stewart B. Rood ◽  
Darla M. Bruns ◽  
Susan J. Smienk
Keyword(s):  
Vegetative Growth ◽  
High Performance ◽  
Shoot Growth ◽  
Developmental Stages ◽  
Shoot Elongation ◽  
Field Trials ◽  
Reversed Phase ◽  
Height Growth ◽  
Forage Production ◽  
Sorghum Bicolor L

Sorghum (Sorghum bicolor (L.) Moench) hybrids adapted for grain (cv. Northrup King X8102) or forage production (cv. Pride PF70) were grown in field trials at Lethbridge, Alta., Canada, and shoot cylinders containing the apical meristems were harvested at various developmental stages for analyses of endogenous gibberellin-like (GA-like) substances. Extracts were purified and chromatographed on sequential SiO2 partition columns and C18 reversed-phase high-performance liquid chromatography, and GA-like substances were detected and quantified by the cv. Tan-ginbozu dwarf rice microdroop assay. Concentrations of GA-like substances in the shoots were higher during vegetative growth than during shoot elongation or panicle elongation and the pattern of declining concentration of GA-like substances was observed for both hybrids over both field seasons. The qualitative distribution of GA-like substances was generally similar across hybrids and developmental stages, with a GA19-like substance accounting for about 60% of the total GA-like activity (GA19 is a native GA of sorghum). The exogenous application of GA3 promoted height growth and inhibited tillering, with maximal effects occurring when application was early, during rapid vegetative growth. Applications of GA3 subsequent to panicle initiation promoted panicle elongation but did not alter the time of anthesis. These results on endogenous GA concentration and response to exogenous GA3 application suggest a role for endogenous GAs in the control of shoot growth and development in sorghum.

Stimulation of flowering by grafted black spruce and white spruce: a comparative study of the effects of gibberellin A4/7, cultural treatments, and environment

1991 ◽  
Vol 21 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Michael S. Greenwood ◽  
Gregory W. Adams ◽  
Michele Gillespie
Keyword(s):  
Black Spruce ◽  
White Spruce ◽  
Shoot Elongation ◽  
Height Growth ◽  
Root Pruning ◽  
Female Cone ◽  
Growth Cycles ◽  
Female Flowering ◽  
Chilling Treatment ◽  
Stimulation Of

Flower stimulation treatments, including gibberellin A4/7 (GA4/7) application, root-pruning, and greenhouse environment during the latter part of shoot elongation, were applied to grafted, clonal black spruce (Piceamariana (Mill.) B.S.P.) and white spruce (Piceaglauca (Moench) Voss) of roughly the same size and age. In addition, the size of pot-grown ramets of both species was increased by inducing additional growth cycles by several applications of a chilling treatment followed by an 18-h photoperiod in a heated greenhouse. This treatment doubled the height growth of both species over a 2-year period, and female cone bud production was promoted by GA4/7. GA4/7 also promoted female flowering on field-grown material, but root-pruning had little effect; black spruce was more responsive to GA4/7 (10× increase) than white spruce (3× increase). Male flowering in black spruce was consistently, and sometimes significantly, inhibited by GA4/7, but was promoted in white spruce. In the latter case the response was not statistically significant. In contrast, male flowering was increased in potted trees of both species by allowing shoots to elongate 50–75% outdoors, after which the trees were moved into a greenhouse.

Effect of applied growth regulators and cultural treatments on flowering and shoot growth of Pinustabulaeformis

1990 ◽  
Vol 20 (6) ◽  
pp. 679-685 ◽  
Author(s):  
Chuxing Sheng ◽  
Shasheng Wang
Keyword(s):  
Shoot Growth ◽  
Root Pruning ◽  
Naphthaleneacetic Acid ◽  
Vegetative Shoot ◽  
Female Cone ◽  
Male Cone ◽  
Female Flowering ◽  
Positive Effect ◽  
Stem Girdling ◽  
Hormonal Treatments

Fourteen treatments expected to promote and regulate flowering were administered to 7-year-old seedlings of Chinese pine (Pinustabulaeformis Carr.), and three were administered to 11-year-old grafted propagules. The cultural treatments, including root pruning, stem girdling, polyethylene mulching, and injection of gibberellin A3 (GA3) significantly increased male cone bud production of the young seedlings. For female flowering, however, only GA4 injection, alone and in combination with root pruning, had a statistically significant positive effect. N6-benzyladenine (BA) injection significantly decreased both male and female cone-bud production. There was no synergistic effect between the cultural and the hormonal treatments on flowering of the seedlings. Treatments with naphthaleneacetic acid dramatically enhanced male cone bud production of the grafted propagules, but did so at the expense of female cone bud production. The hormonal treatments (GA3, GA4, and BA injection) all promoted vegetative shoot growth of the treated seedlings. The cultural treatments generally inhibited shoot length growth and had no significant effect on diameter growth.

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