Bud development in mountain hemlock (Tsuga mertensiana). I. Vegetative bud and shoot development

1984 ◽  
Vol 62 (3) ◽  
pp. 475-483 ◽  
Author(s):  
John N. Owens
Keyword(s):  
Growth Cycle ◽  
Shoot Development ◽  
Bud Development ◽  
Vegetative Buds ◽  
Lateral Shoots ◽  
Tsuga Mertensiana ◽  
Terminal Buds ◽  
Lateral Branches ◽  
Relationship Of ◽  
Vegetative Bud

Vegetative buds of mature Tsuga mertensiana (Bong) Carr. (mountain hemlock) were studied throughout the annual growth cycle. Cell divisions began in vegetative buds in mid-April and shoots and leaves elongated within the bud scales causing the buds to burst in late June. Lateral shoots completed elongation by the end of July. Vegetative terminal apices from lateral branches began bud-scale initiation when bud dormancy ended. All bud scales were initiated by the end of July. Leaf primordial initiation occurred from that time until mid-October when vegetative buds again became dormant. Axillary buds were initiated on the elongating shoots in early June then followed the same phenology as vegetative terminal buds. Vegetative bud and shoot development are compared with that of western hemlock and certain other members of the Pinaceae. The relationship of bud development to shoot development is discussed for mountain hemlock and other conifers having a similar pattern of vegetative bud development.

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 Picea glauca. I. Annual growth cycle of vegetative buds and shoot elongation as they relate to date and temperature sums

1977 ◽  
Vol 55 (21) ◽  
pp. 2728-2745 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder ◽  
Hilary Langer
Keyword(s):  
Picea Glauca ◽  
Shoot Growth ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Bud Dormancy ◽  
Annual Growth ◽  
Bud Development ◽  
Leaf Initiation ◽  
Vegetative Buds ◽  
Vegetative Bud

Vegetative buds of Picea glauca (Moench) Voss were studied throughout the annual growth cycle in several trees in 1975 and 1976 and bud development was related to lateral vegetative shoot growth, date, and temperature sums.Vegetative buds became mitotically active in mid-April at lower elevations and about 6 weeks later at higher elevations. Shoot elongation was characterized by similar smooth sigmoid curves in both years. Shoot growth was slow for the 1st month, rapid during the 2nd month, and slow again for the 3rd month and ended by early August. Temperature sums related best to percentage of shoot elongation if the end of vegetative bud dormancy was used as the starting date and 5 °C was used as the threshold temperature. Arbitrarily chosen starting dates and threshold temperatures gave temperature sums which were related to shoot elongation only when shoot elongation was nearly completed. Generally, if the end of vegetative bud dormancy is known, the number of days from that time is nearly as accurate as the more complex use of temperature sums in predicting the percentage of shoot elongation or the stage of vegetative bud development.Bud-scale initiation occurred during shoot elongation. Axillary buds were initiated in mid-May and flushing occurred when shoots had elongated to about 30% of their final length in late May or early June. The end of shoot elongation coincided with the onset of leaf initiation on all trees in both years. The change from bud-scale initiation to leaf initiation was preceded by a marked increase in apical width and a slight increase in apical height and mitotic frequency. Leaf initiation was rapid for 6 weeks then slower for the last 4 weeks. Vegetative buds became dormant in mid-October.Vegetative bud development is closely related to shoot elongation. Breaking of vegetative bud dormancy was not affected by temperature but shoot elongation and flushing were affected by temperatures which occurred after dormancy was broken.

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 Picea engelmannii. I. Vegetative bud development, differentiation, and early development of reproductive buds

1983 ◽  
Vol 61 (9) ◽  
pp. 2291-2301 ◽  
Author(s):  
Derek L. S. Harrison ◽  
John N. Owens
Keyword(s):  
Shoot Elongation ◽  
Longitudinal Axis ◽  
Leaf Primordia ◽  
Axillary Buds ◽  
Picea Engelmannii ◽  
Bud Burst ◽  
Bud Development ◽  
Vegetative Buds ◽  
Terminal Buds ◽  
Mother Cells

Vegetative buds of Engelmann spruce (Picea engelmannii Parry) from the Prince George Forest District (British Columbia) were collected and studied. In mid-April, dormancy ended as determined from mitotic divisions within the leaf primordia; 2 weeks later mitotic activity occurred in the bud apices. Bud-scale initiation began in terminal buds by late May followed by that in axillary buds 2 weeks later. Shoot elongation began in late May, bud burst occurred in late June, and both shoot elongation and bud-scale initiation were complete by late July. Terminal buds began to differentiate by the initiation of leaf primordia, into vegetative buds early in August whereas axillary buds began to differentiate 1 week later. Leaf initiation was completed in all vegetative buds by late September and buds were dormant by mid-October. Pollen cones initiated microsporophylls after bud-scale initiation. Microsporangial initiation began in late August. Microsporangial enlargement began in mid-September and continued until dormancy when pollen mother cells were observed in a premeiotic stage. Seed cones initiated bracts directly after bud-scale initiation. In mid-August, ovuliferous scales began to be initiated. Two ovule primordia formed adaxially, one on each side of the median longitudinal axis of each ovuliferous scale. Each ovule formed one large central megaspore mother cell which overwintered in a premeiotic stage.

Bud development in western hemlock. I. Annual growth cycle of vegetative buds

1973 ◽  
Vol 51 (11) ◽  
pp. 2223-2231 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Mitotic Activity ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Leaf Primordia ◽  
Annual Growth ◽  
Western Hemlock ◽  
Bud Burst ◽  
Bud Development ◽  
Vegetative Buds ◽  
Number Of Leaves

Vegetative apices of mature Tsnga heterophylla (Raf.) Sarg. were studied throughout the annual growth cycle. Apices become mitotically active during the last week of March. Leaf primordia elongate, causing the buds to swell, while the apex remains small and produces bud scales. Axillary buds are initiated about mid-April. Little shoot elongation occurs before vegetative buds burst in mid-May. After bud burst, rapid shoot elongation occurs for about 7 weeks, during which time the apex also elongates and the rest of the bud scales are initiated. There is a marked increase in mitotic activity in the apex during the transition from bud-scale initiation to leaf initiation, which occurs early in July when the grand phase of shoot elongation is complete. This is believed to be the time when vegetative apices undergo transition to become reproductive apices. Leaf primordia are initiated in rapid succession until mid-August, when two-thirds of the final number of leaves are initiated and the subtending shoot is fully elongated. From mid-August until mid-November, no shoot elongation occurs, leaf primordia are initiated more slowly, and mitotic activity in the apex gradually decreases. After all of the next season's leaves have been initiated, about mid-November, mitotic activity in the apex stops and the vegetative buds become dormant.

Shoot ontogeny in Arctostaphylos uva-ursi (bearberry): the annual cycle of apical activity

1984 ◽  
Vol 62 (9) ◽  
pp. 1925-1932 ◽  
Author(s):  
W. R. Remphrey ◽  
T. A. Steeves
Keyword(s):  
Leaf Primordia ◽  
Growth Strategy ◽  
Bud Burst ◽  
Foliage Leaf ◽  
Lateral Buds ◽  
Previous Season ◽  
Lateral Shoots ◽  
Terminal Buds ◽  
Floral Bracts ◽  
Vegetative Bud

Phenological investigation of shoot ontogeny in the prostrate shrub Arctostaphylos uva-ursi (L.) Spreng. (bearberry) at two sites in Saskatchewan, Canada, revealed that most growth occurred from May to July. Vegetative bud swell and leaf primordium initiation began around the 1st of May. Following bud burst in late May, elongation of most shoots continued for 3 to 5 weeks. Most bearberry shoots were not completely preformed; that is, several neoformed foliage leaves were initiated during current-year shoot extension in addition to the leaves that had been preformed during the previous season and had overwintered in the bud. In many shoots, a terminal inflorescence was initiated in the latter part of May of the year prior to anthesis. During conversion to the flowering state, the terminal apex initiated seven to nine floral bracts, each subtending a bud. In vegetative terminal shoots, bud-scale initiation also began in mid-May to late May and new terminal buds were first evident in early to mid-June. Following the initiation of bud scales and transitional leaves, the production of preformed foliage-leaf primordia continued until about August 1. Protruding lateral buds were evident histologically in the axils of preformed leaves during the initial stages of bud swell. On long, dominant shoots numerous neoformed leaves were initiated and shoot extension was often prolonged well into August. Second-flush terminal and lateral shoots, which resulted from the expansion of neoformed leaves and internodes, were also observed. The occurrence of neoformed growth in a large proportion of shoots suggests an exploitive, opportunistic growth strategy in this species.

Bud development in grand fir (Abiesgrandis)

1984 ◽  
Vol 14 (4) ◽  
pp. 575-588 ◽  
Author(s):  
John N. Owens
Keyword(s):  
Shoot Elongation ◽  
Lower Surface ◽  
Growth Cycle ◽  
Axillary Buds ◽  
Bud Burst ◽  
Leaf Initiation ◽  
Cone Production ◽  
Vegetative Buds ◽  
Seed Cone ◽  
Terminal Buds

Vegetative buds of mature Abiesgrandis (Dougl.) Lindl. (grand fir) were studied throughout the annual growth cycle. Vegetative buds became mitotically active in mid-March, bud burst occurred in mid-May, and shoot elongation continued until the end of June. Bud scales were initiated during shoot elongation. In mid-April axillary buds were initiated on elongating shoots. They were initiated subterminally in the axils of the first-formed bud scales and laterally in the axils of leaf primordia. Axillary buds followed the same developmental sequence as terminal buds. The end of bud-scale initiation was preceded by rapid apical enlargement and followed by a period of rapid leaf initiation. The rate of leaf initiation slowed in mid-August but continued until vegetative buds became dormant in mid-November. Seed cones are axillary on the upper surface of vigorous shoots in the upper region of the crown. Pollen cones are axillary on the lower surface of shoots below the seed cone bearing region of the crown. Bract and microsporophyll initiation began in early to mid-July, was rapid at first, until about two-thirds of the primordia were initiated, then slower until all primordia were initiated. All bracts and ovuliferous scales were initiated and seed-cone buds became dormant in early November. All microsporophylls were initiated by early September, microsporangial development began in mid-August, and pollen-cone buds became dormant in early November. The cyclic nature of cone production in Abies is discussed in relation to cone-bud initiation, cone maturation, and photosynthate utilization in developing shoots.

Vegetative bud development and the time and method of cone initiation in subalpine fir (Abies lasiocarpa)

1982 ◽  
Vol 60 (11) ◽  
pp. 2249-2262 ◽  
Author(s):  
John N. Owens ◽  
Hardev Singh
Keyword(s):  
Shoot Elongation ◽  
Axillary Bud ◽  
Abies Lasiocarpa ◽  
Bud Burst ◽  
Rapid Phase ◽  
Bud Development ◽  
Vegetative Buds ◽  
Seed Cone ◽  
Pollen Cone ◽  
Vegetative Bud

Vegetative terminal and axillary bud development and the time and method of cone initiation and cone bud development are described for Abies lasiocarpa (Hook.) Nutt.Cell divisions began in vegetative buds early in April. A brief period of apical enlargement was followed by bud-scale initiation for 10 weeks. Buds were initiated in the axils of some leaf primordia about the time of vegetative bud burst, 1 month after vegetative bud dormancy ended. All buds completed bud-scale initiation by the end of June, which coincided with the end of the rapid phase of lateral shoot elongation. This was followed by a 2-week period of bud differentiation, during which time few primordia were initiated, apical size increased, and apical shape and zonation changed more in reproductive than in vegetative apices. Leaf and bract initiation began by mid-July and continued until mid-October, when vegetative and seed-cone buds became dormant. Microsporophyll initiation began earlier and was nearly completed by the end of July; pollen-cone buds became dormant in mid-September.The number of cone buds is determined by the proportion of axillary bud primordia that fully developed and the pathway along which they developed. Potential seed-cone buds may become latent but more commonly differentiate into vegetative buds of low vigor. Potential pollen-cone buds frequently become latent but have not been observed to differentiate into vegetative buds. The position of the axillary bud on the shoot and of the shoot in the tree strongly influences axillary bud development in Abies.

Bud development in Larix occidentalis. I. Growth and development of vegetative long shoot and vegetative short shoot buds

1979 ◽  
Vol 57 (7) ◽  
pp. 687-700 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Growth And Development ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Leaf Primordia ◽  
Axillary Buds ◽  
Larix Occidentalis ◽  
Short Shoot ◽  
Bud Development ◽  
Shoot Buds ◽  
Vegetative Bud

Vegetative terminal long shoot buds (TLSB) and short shoot buds (SSB) were studied throughout the annual growth cycle in several trees over several years. TLSB were not totally preformed. The dormant TLSB consisted of bud scales enclosing some basal leaves and both were borne on a broad receptacle. Centripetal to the basal leaves, a series of axial leaf primordia was borne on the flanks of the apex. After dormancy a second series of axial leaves was initiated above those initiated before dormancy. Basal and both series of axial leaves elongated during shoot elongation as the terminal apex again initiated axial leaves, bud scales, and then basal leaves. After shoot elongation the first series of axial leaves was initiated before the TLSB became dormant in October. No dimorphism occurred between predormancy and postdormancy axial leaves or axial and basal leaves. Axilliary buds were initiated in the TLSB about the time of flushing. All leaves did not bear axillary buds. All axillary buds rapidly initiated a series of bud scales and then entered a slower phase of bud-scale initiation and rapid apical enlargement. Leaf primordia then were initiated at the base of the apex and borne on the broad receptacle. Apices then differentiated into axillary long shoot buds (ALSB) or SSB. ALSB developed similarly to TLSB, whereas axillary SSB initiated leaf primordia at the base of the apex and all but the last primordia to be initiated were borne on the broad receptacle. Axillary SSB were preformed but ALSB were not completely preformed and both became dormant in mid-October. The apex of a short shoot lived for up to 8 to 10 years. In each successive year it passed through phases of bud-scale initiation and leaf initiation to form a dormant preformed SSB which flushed after overwintering. Annual short shoot elongation was about 1 mm. The LSB and SSB apices varied in shape and size during the year but apical zonation was similar in all apices. Larix vegetative bud development is compared with that found in other gymnosperms.

scholarly journals OSMOTIC POTENTIAL IS RELATED TO SINK STRENGTH IN VEGETATIVE AND FLORAL BUDS OF APPLE AND PEACH

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 613c-613
Author(s):  
W.G. Yang ◽  
D.M. Glenn
Keyword(s):  
Growth Rate ◽  
Osmotic Potential ◽  
Leaf Growth ◽  
Sink Strength ◽  
Stages Of Development ◽  
Embryo Survival ◽  
Bud Development ◽  
Floral Buds ◽  
Vegetative Buds ◽  
Vegetative Bud

The osmotic potential and development of apple and peach floral and vegetative buds and tissue were determined pre- and post-bloom. Apple and peach floral and vegetative buds were removed pre-bloom and the osmotic potential and bud development measured pre- and post-bloom. The osmotic potential of vegetative and floral buds was related to the phenology of bud development. Developing buds had a lower (more negative) osmotic potential than dormant buds. Removal of peach floral buds lowered osmotic potential and increased vegetative bud development and early leaf growth rate. Removal of peach vegetative buds, however, reduced fruit bud development, fruit growth, and embryo survival. Osmotic potential was an index of sink activity during the pre- and post-bloom stages of development.

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