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.

Bud development in mountain hemlock (Tsuga mertensiana). II. Cone-bud differentiation and predormancy development

1984 ◽  
Vol 62 (3) ◽  
pp. 484-494 ◽  
Author(s):  
John N. Owens
Keyword(s):  
Shoot Elongation ◽  
Bud Development ◽  
Seed Cone ◽  
Cone Apex ◽  
Tsuga Mertensiana ◽  
Lateral Branches ◽  
Mother Cells ◽  
Pollen Cone ◽  
Bud Initiation ◽  
Vegetative Bud

Seed cones of Tsuga mertensiana (Bong) Carr. occur terminally on distal lateral branches and form from the differentiation of a terminal, previously vegetative apex, into a seed-cone apex. Pollen cones commonly occur on lateral branches and form from the differentiation of an undetermined axillary apex about 6 weeks after axillary bud initiation. Pollen cones also occasionally occur terminally. All cone buds began differentiation in late July after bud-scale initiation was complete and at about the end of lateral shoot elongation. Seed-cone buds initiated bracts and ovuliferous scales, but not ovules, before they became dormant at the end of October. Pollen-cone buds initiated all microsporophylls by early September. Microsporangia containing microspore mother cells differentiated before pollen-cone buds became dormant in mid-October. The time of cone-bud differentiation is related to vegetative bud and shoot development. The time and method of cone-bud differentiation is discussed in relation to T. heterophylla and other conifers having similar bud development.

Bud development in Sitka spruce. II. Cone differentiation and early development

1976 ◽  
Vol 54 (8) ◽  
pp. 766-779 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Phenolic Compounds ◽  
Early Development ◽  
Shoot Elongation ◽  
Picea Sitchensis ◽  
Lateral Shoot ◽  
Bud Development ◽  
Seed Cone ◽  
Mitotic Frequency ◽  
Mother Cells ◽  
Pollen Cone

Pollen-cone and seed-cone buds of Picea sitchensis (Bong.) Carr. are found as either terminal or axillary buds. Pollen cones are most likely to develop from small axillary apices on vigorous distal shoots or small terminal apices on less vigorous, proximal shoots. Seed cones are most likely to develop from large, distal axillary apices on vigorous shoots or smaller terminal apices on less vigorous shoots. All apices became mitotically active late in March, passed through a 3.5-month period of bud-scale initiation, and in mid-July became differentiated as vegetative, pollen-cone, or seed-cone apices. Potentially pollen-cone apices were smaller, had a lower mitotic frequency during bud-scale initiation, and produced fewer bud scales than apices which developed into seed-cone or vegetative buds. During bud-scale initiation all apices had a few strands of cells containing phenolic compounds in the developing pith. At the time of bud differentiation, the pith of vegetative apices accumulated more phenolic compounds and non-phenolic ergastic materials, whereas the pith of reproductive apices did not. This was followed by a marked increase in mitotic frequency in reproductive apices, resulting in changes in apical size and shape. Leaf, bract, and microsporophyll initiation began about the end of July. All microsporophylls were initiated by the end of August. Sporogenous cells developed, but meiosis did not occur before the pollen cones became dormant at the end of October. Two-thirds of the bracts were initiated by the end of August. The remaining bracts were initiated more slowly until dormancy. Ovuliferous scales were initiated for 3 months beginning in September, and megaspore mother cells appeared but did not undergo meiosis before seed cones became dormant at the end of November. There was no difference in the time of vegetative, pollen-cone, and seed-cone bud differentiation, which occurred at the end of lateral shoot elongation.

Girdling: its effect on carbohydrate status and on reproductive bud and cone development of Douglas fir

1971 ◽  
Vol 49 (3) ◽  
pp. 453-466 ◽  
Author(s):  
L. F. Ebell
Keyword(s):  
Shoot Elongation ◽  
Douglas Fir ◽  
Bud Break ◽  
Variable Response ◽  
Bud Development ◽  
Cone Production ◽  
Carbohydrate Concentration ◽  
Cone Development ◽  
Food Reserves ◽  
Vegetative Bud

Partial girdles were applied in August, 1957, to one stem of two double-stemmed, 20-year-old Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). The second stem served as control. A third double-stemmed tree was treated in May, 1958. Cone production responses were obtained on all three girdled stems, averaging 7.4 times that of control stems in 1959, and 1.6 and 2.3 times that of control stems in 1961 and 1962. Cone production responses to treatment, and cone crop variation over several years were correlated with reduced bud failure during the period of new shoot elongation. Total number of buds per shoot was initially similar for paired stems. These relationships indicated a predetermined potential for annual cone production, and that cone crop periodicity is determined by later conditions favorable or unfavorable to continued early bud development. Treatment increased both sugars and starch in shoots sampled 40 days after August girdling, but only starch remained elevated the next spring and throughout the decisive May–June period of reproductive bud development. Other factors indicated food reserves to be related only weakly to reproductive bud survival. Cone production reduced carbohydrate concentration in shoots of all ages, growth and number of new shoots, and number of developed buds per shoot. These factors explain the absence of consecutive cone crops in Douglas fir, and suggest that cone inducing treatments should not be applied in good flowering years. Cone production responses on single-stemmed trees girdled at weekly intervals showed an optimum timing coincident with the onset of flowering, a more variable response up to the time of vegetative bud break, then an adverse effect on cone production when girdled later than 1 week after vegetative bud break.

Vegetative bud development and cone differentiation in Abies amabilis

1977 ◽  
Vol 55 (8) ◽  
pp. 992-1008 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Shoot Elongation ◽  
Leaf Primordia ◽  
Bud Burst ◽  
Lateral Shoot ◽  
Vegetative Buds ◽  
Seed Cone ◽  
Mitotic Frequency ◽  
Mother Cells ◽  
Pollen Cone ◽  
Vegetative Bud

In the trees studied, vegetative buds began development in early April, bud burst occurred in early June and shoot elongation was completed by late July. Vegetative buds initiated bud scales from mid-April until mid-July and then initiated leaf primordia until the vegetative buds became dormant in November. All axillary buds were initiated in mid-May and their bud scales were initiated until early July. During bud-scale initiation, distal vegetative lateral apices were more conical but had a mitotic frequency similar to other lateral apices. Near the end of bud-scale initiation, vegetative apices accumulated more phenolic and ergastic compounds in future pith cells than did potential seed-cone or pollen-cone apices. Bud differentiation occurred in mid-July at the end of lateral shoot elongation. During bud differentiation the mitotic frequency of pollen-cone and seed-cone apices increased much more than that of distal vegetative apices. This resulted in a marked increase in apical size and a change in apical shape and zonation that made reproductive apices easily distinguishable from vegetative apices. Bracts began to be initiated in mid-July, and ovuliferous scales, in mid-August. Both continued to be initiated until seed-cone buds became dormant in November. A single megaspore mother cell formed in each ovule before dormancy. Microsporophylls were initiated from mid-July until early September. Microsporangia began to differentiate in September and contained microspore mother cells when pollen cones became dormant in mid-October. Meiosis did not begin before dormancy. A few potential vegetative and many potential seed-cone and potential pollen-cone apices became latent during bud-scale initiation. Some potential seed-cone apices became vegetative buds. Consequently, the number of cone buds formed was determined primarily by the proportion of apices that developed fully and the pathway along which they developed.

Gibberellin A4/7 enhances seed-cone production in field-grown black spruce

1988 ◽  
Vol 18 (1) ◽  
pp. 139-142 ◽  
Author(s):  
Rong H. Ho
Keyword(s):  
Vitamin E ◽  
Black Spruce ◽  
Seed Orchard ◽  
Shoot Elongation ◽  
Bud Burst ◽  
Lateral Shoot ◽  
Cone Production ◽  
Seed Cone ◽  
Vegetative Bud ◽  
Needle Primordia

Black spruce (Piceamariana (Mill.) B.S.P.) grafts growing in a seed orchard were sprayed with gibberellin A4/7, and grafts and trees in families growing in arboreta were sprayed with gibberellin A4/7 and (or) vitamin E from vegetative bud burst to the end of shoot elongation. Gibberellin A4/7 was very effective in promoting seed cones and 400 mg/L appeared optimal. Vitamin E at 1000 mg/L was not effective. Vegetative bud burst occurred in mid-May and shoot elongation ended in late June. Needle primordia were visible on the apices of newly formed buds at the end of June. Reproductive buds had fewer bud scales than vegetative buds. It appeared that potential reproductive buds terminated their bud scale initiation earlier. Gibberellin A4/7 application to promote seed-cone production should be carried out before bud-type differentiation. This coincides with the end of lateral shoot elongation.

scholarly journals Rooting and Lateral Shoot Elongation of Verbena Following Benzylaminopurine Application

HortScience ◽  
1991 ◽  
Vol 26 (4) ◽  
pp. 391-392 ◽  
Author(s):  
Sven E. Svenson
Keyword(s):  
Foliar Application ◽  
Shoot Elongation ◽  
Dry Mass ◽  
Stem Cuttings ◽  
Stock Plant ◽  
Lateral Shoot ◽  
Rooting Zone ◽  
Nodal Roots ◽  
Lateral Bud ◽  
Rooting Response

Rooting and growth of Verbena cuttings (Verbena × hybrids Voss) were measured to determine response to foliar-applied benzylaminopurine (BA). There was no rooting response to BA application when visible nodal roots were present at the base of the cutting. There was no response to 30, 100, or 300 mg BA/liter applied to the foliage 48 or 96 hours after excision from the stock plant. Rooting-zone dry mass, total cutting dry mass, and number of roots were increased by 30 mg BA/liter applied immediately after excision when there were no visible nodal roots at the base of the cuttings. Foliar application of BA at 10 or 30 mg·liter-1 increased lateral bud elongation of subsequently rooted shoots by 20% and 49%, respectively. Application of BA during cutting propagation to enhance subsequent lateral bud elongation does not appear to inhibit rooting in Verbena stem cuttings. Chemical name used: 6-benzylaminopurine (BA).

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.

The relative importance of initiation and early development on cone production in Douglas fir

1969 ◽  
Vol 47 (7) ◽  
pp. 1039-1049 ◽  
Author(s):  
John N. Owens
Keyword(s):  
Vegetative Growth ◽  
Succinic Dehydrogenase ◽  
Douglas Fir ◽  
Relative Importance ◽  
Succinic Dehydrogenase Activity ◽  
Cyclic Pattern ◽  
Cone Production ◽  
Lateral Buds ◽  
Lateral Bud ◽  
Bud Initiation

Lateral bud initiation as determined by increased succinic dehydrogenase activity in the axils of certain leaves occurs by April 1 in the Victoria area. The number of lateral buds initiated did not vary significantly in 1967 and 1968 while the number of buds which developed did. Not all primordia which are initiated develop. Some abort very early and disappear completely while others develop bud scales then cease development and become latent. The rest of the primordia fully develop as vegetative, male, or female buds. In 1967 when abundant cones developed, 56% of the primordia fully developed and most of these became reproductive buds. In 1968 when no cones developed, only 31% of the primordia fully developed and all of these became vegetative. The number of cones produced was, therefore, not determined directly by the number of primordia initiated but by the proportion of primordia which developed as reproductive buds. The presence of abundant maturing cones on shoots formed the previous year greatly reduces the number of primordia which develop and, also, reduces the possibility of these becoming reproductive buds. Previous vegetative growth and cone crops affect the cone productivity in subsequent years and help explain the cyclic pattern of reproduction in Douglas fir.

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.

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