Bud development in Larix occidentalis. II. Cone differentiation and early development

1979 ◽  
Vol 57 (14) ◽  
pp. 1557-1572 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Shoot Elongation ◽  
Larix Occidentalis ◽  
Short Shoot ◽  
Bud Development ◽  
Seed Cone ◽  
Long Shoots ◽  
Short Shoots ◽  
Old Trees ◽  
Mother Cells ◽  
Pollen Cone

The time and method of cone-bud differentiation and the phenology of cone-bud development were studied in 10- to 20-year-old trees growing outside their natural range and three 50-year-old trees growing within their natural range.Both pollen-cone and seed-cone buds of western larch (Larix occidentalis Nutt.) normally differentiated on short shoots that were at least 1 year old. Pollen-cone buds were commonly on proximal nonvigorous, often pendant vegetative long shoots in lower regions of the crown, whereas seed-cone buds were usually found on distal short shoots on vigorous but less pendant vegetative long shoots in upper regions of the crown.All potential cone buds were indistinguishable from potential vegetative short shoot buds during bud-scale initiation. In early June, when vegetative short shoots had begun to initiate leaves, cone-bud apices entered a period of differentiation during which time the mitotic frequency of the apices greatly increased followed by a marked increase in apical size. During differentiation, pollen-cone apices did not initiate any basal foliar organs and a short stalk resulted at the base of the cone, whereas seed-cone apices initiated a few basal foliar primordia before bract initiation began. Microsporophyll initiation began during the last half of June and initiation occurred rapidly until the end of July. Micros porangial development occurred from August to late October when fully developed pollen-cone buds became dormant. Pollen mother cells began meiosis before dormancy and overwintered at the diffuse stage. Bract initiation began about the end of June, was rapid until mid-August, then continued more slowly until seed-cone buds became dormant in late October. Ovuliferous scales were initiated acropetally from mid-August until dormancy. Cone-bud differentiation occurred at about the end of the period of vegetative lateral long shoot elongation at all locations.

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.

Bud development in western hemlock. II. Initiation and early development of pollen cones and seed cones

1974 ◽  
Vol 52 (2) ◽  
pp. 283-294 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Tsuga Heterophylla ◽  
Day Length ◽  
Western Hemlock ◽  
Reproductive State ◽  
Bud Development ◽  
Seed Cone ◽  
Cone Apex ◽  
Lateral Branches ◽  
Mother Cells ◽  
Pollen Cone

Seed cones in Tsuga heterophylla (Raf.) Sarg. are found at the tips of distal lateral branches and form as a result of the transition of a previously vegetative apex. Pollen cones may be formed similarly and are then found at the tips of less-vigorous proximal branches but more commonly they develop from newly initiated axillary buds on short proximal shoots. In all cases, apices undergo transition to the reproductive state after a period of bud-scale initiation. Some apices initiate many bud scales, then either initiate leaves or undergo transition to a seed-cone apex in July. Other apices initiate fewer bud scales, then late in June undergo transition to a pollen-cone apex. Transition to a reproductive apex is marked by an increase in mitotic activity and apical size and loss of the vegetative pattern of zonation. Zonation reappears during the slower period of late bract and microsporophyll initiation but is not as prominent as it was in vegetative apices. In seed-cone buds, all bracts, ovuliferous scales, and megaspore mother cells are formed before dormancy. In pollen-cone buds all microsporophylls and microsporangia are initiated before dormancy and pollen mother cells begin meiosis and remain in the diffuse diplotene stage during dormancy. Pollen- and seed-cone buds become dormant in December. The time of cone initiation and sexuality of cones may be influenced by day length. The pattern of reproduction in western hemlock is compared in some respects with that of other conifers.

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.

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.

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.

Production and distribution of seed and pollen cones on Larixlaricina trees in young plantations

1991 ◽  
Vol 21 (4) ◽  
pp. 446-454 ◽  
Author(s):  
Kathleen J. Tosh ◽  
G. R. Powell
Keyword(s):  
Seed Cone ◽  
Production And Distribution ◽  
Long Shoots ◽  
Short Shoots ◽  
Pollen Cone

Numbers and distributions of seed and pollen cones were assessed on 90 Larixlaricina (Du Roi) K. Koch trees of 5, 6, and 7 years. Respectively, 27, 90, and 96% of the trees bore seed cones and 0, 62, and 96% bore pollen cones. Numbers of seed cones per tree averaged 9, 206, and 390 and of pollen cones, 0, 42, and 838. Ninety-nine, 88, and 30% of the seed cones were borne laterally on long shoots. At ages 6 and 7 years, 22 and 2% of the pollen cones were borne laterally. Seed cones occurred equally on side or lower surfaces of parent long shoots, but pollen cones were mainly on lower surfaces. Lateral cones were mainly borne proximally on the parent long shoots at first production; later, some were medial and a few were distal. Proportions of short shoots bearing seed cones increased acropetally. More short shoots bearing pollen cones were medial than proximal or distal. At age 6, proximal short shoots bearing pollen cones exceeded distal ones: the reverse occurred at age 7. Seed-cone and pollen-cone zones were not separate in the crowns, but within any shoot category, seed cones predominated on stronger shoots and pollen cones on weaker shoots.

Bud development in Picea glauca. II. Cone differentiation and early development

1977 ◽  
Vol 55 (21) ◽  
pp. 2746-2760 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Picea Glauca ◽  
Shoot Elongation ◽  
Accurate Method ◽  
Optimal Time ◽  
Seed Cone ◽  
Mitotic Frequency ◽  
Mother Cells ◽  
Pollen Cone ◽  
Vegetative Bud ◽  
Made In

Pollen-cone and seed-cone buds of Picea glauca (Moench) Voss occurred as either terminal or axillary buds. All apices initiated bud scales from late April until mid-July and then differentiated into vegetative, pollen-cone, or seed-cone apices. Potentially pollen-cone apices were usually smaller, had a lower mitotic frequency, and initiated fewer bud scales than potentially vegetative or seed-cone apices. In late July a marked increase in mitotic frequency occurred in differentiating reproductive apices resulting in changes in apical size, shape, and zonation. Leaf, bract, and microsporophyll initiation began at the end of July. All microsporophylls were initiated by early October when pollen-cone buds became dormant. Sporogenous cells had differentiated but meiosis had not begun. Bract initiation began in early August and ovuliferous scale initiation began in late August. Initiation of both stopped in mid-October when seed-cone buds became dormant. Megaspore mother cells were present in dormant seed-cone buds but had not begun meiosis.There was no difference in the time of vegetative, pollen-cone, or seed-cone bud differentiation at the four locations from which collections were made in 1975 and 1976. Differentiation coincided with the end of lateral shoot elongation which was during the last half of July. These results agree with another report from one location in Ontario. Temperature sums also could be an accurate method of determining the time of cone-bud differentiation if calculations were based on the end of vegetative bud dormancy rather than on more arbitrary starting dates. The methods may be applicable to other members of the Pinaceae to determine the optimal time for cone induction treatments.

Leaf area development on different shoot types in a young aspen stand and its effect upon production

1970 ◽  
Vol 48 (10) ◽  
pp. 1801-1804 ◽  
Author(s):  
D. F. W. Pollard
Keyword(s):  
Leaf Area ◽  
Total Production ◽  
Short Shoot ◽  
Area Index ◽  
Young Leaves ◽  
Long Shoots ◽  
Short Shoots ◽  
Area Development ◽  
Leaf Area Development ◽  
Photosynthetic Efficiencies

Different shoot types in aspen crowns carried leaves of different ages; leaders continued to produce leaves until early August and always carried some young leaves, whereas short shoots completed development by mid-June. Development of foliage on long shoots was intermediate between that on leaders and short shoots. Leaf area index of the 6-year-old stand reached a maximum of 2.4, of which 2.1 was contributed by short-shoot foliage. The rest was formed by leaders and long shoots. Young leaves on leaders and long shoots were not sufficient to influence total production in the stand appreciably, even though young aspen leaves may have high photosynthetic efficiencies. These young leaves could, however, influence height growth and lateral development of the canopy.

Shoot type demography and dry matter partitioning: a morphometric approach in apple (Malus ×domestica)

2001 ◽  
Vol 79 (11) ◽  
pp. 1270-1273 ◽  
Author(s):  
Pierre-Éric Lauri ◽  
Jean-Jacques Kelner
Keyword(s):  
Leaf Area ◽  
Malus Domestica ◽  
Detrimental Effect ◽  
Canopy Structure ◽  
Short Shoot ◽  
Dry Matter Partitioning ◽  
Fruiting Branch ◽  
Long Shoots ◽  
Short Shoots ◽  
Time Required

In a study of the apple (Malus ×domestica Borkh.) canopy structure, 5-year-old 'Fuji' and 'Braeburn' trees grafted on a low-vigour rootstock (M9) were compared at both fruiting branch and shoot levels. Percentages of short ([Formula: see text]5 cm) shoots and short shoot leaf area were significantly higher on 'Braeburn' than on 'Fuji', (76.8% vs. 72.6% and 46.9% vs. 42.9% for 'Braeburn' and 'Fuji', respectively). This high percentage of short shoots as compared with literature data was probably due to the training method, which reduced vigour. At shoot level, the ratio between dry masses of axis and leaf, called the axialization index, was determined to compare short and long shoots. Axialization values were higher for 'Braeburn' than for 'Fuji'. Although overall and individual leaf area was greater on long shoots, long shoot axialization (0.64 and 0.54 for 'Braeburn' and 'Fuji', respectively) was approximately twice that of short shoots (0.36 and 0.24, respectively). Therefore, for short shoots, the reduced carbon investment in supporting tissues may explain the significant role short shoots played in supporting early fruit development. For long shoots, the longer time required to reach the autotrophic and then exporting stage as well as the detrimental effect of early extension shoot development on fruit set might be explained by greater axialization.Key words: long shoot, short shoot, axialization index, apple, Malus ×domestica, biomass partitioning.

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