Cone initiation and development before dormancy in yellow cedar (Chamaecyparis nootkatensis)

1974 ◽  
Vol 52 (9) ◽  
pp. 2075-2084 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Mitotic Activity ◽  
Lateral Branch ◽  
Leaf Primordia ◽  
Day Length ◽  
Chamaecyparis Nootkatensis ◽  
Seed Cone ◽  
Cone Development ◽  
Cone Apex ◽  
Lateral Branches ◽  
Pollen Cone

Vegetative shoots initiate leaves and lateral branches continuously from mid-April until the end of September. No buds with bud scales are formed and the vegetative apex is enclosed by leaf primordia at various stages of development. Pollen cones are initiated on proximal vegetative shoots during a 3-week period from mid-June to early in July. Transition to a pollen-cone apex is marked by an increase in mitotic activity in the apex and by the formation of a lateral branch in the axil of one of the last-formed leaf primordia, causing the apex to appear to branch dichotomously. The lateral branch remains at the base of the pollen cone and may resume growth the next year after the pollen cone is shed. Pollen-cone development continues until the end of September. Meiosis occurs during the last 2 weeks of August, and pollen develops during September. Seed cones are initiated on newly formed, distal axillary vegetative shoots during a 3-week period from late June to mid-July. Transition to a seed-cone apex is marked by an increase in mitotic activity followed by bract-scale initiation. Usually three ovules are initiated in the axil of each bract scale. Seed-cone development is complete by early September and the seed cones become dormant. The pattern of reproduction in yellow cedar is compared to other conifers and the possible relationships are discussed between time of cone initiation, sexuality of cones, and day length.

Initiation and development of western red cedar cones in response to gibberellin induction and under natural conditions

1971 ◽  
Vol 49 (7) ◽  
pp. 1165-1175 ◽  
Author(s):  
J. N. Owens ◽  
R. P. Pharis
Keyword(s):  
Cold Treatment ◽  
Day Length ◽  
Thuja Plicata ◽  
Natural Conditions ◽  
Red Cedar ◽  
Cone Type ◽  
Cone Development ◽  
Cone Apex ◽  
Lateral Branches ◽  
Pollen Cone

Both seed and pollen cones in Thuja plicata Donn. are found at the tips of small lateral branches and form as a result of the transition of previously vegetative apices. The vegetative apex shows a cytohistological zonation similar to that found in other Cupressaceae and vegetative buds are not enclosed in scales. The first sign of pollen cone initiation occurred 13 days after the initial GA3 treatment under long days. Transition of the apex was marked by a slight increase in rate of cell division in all zones resulting in the formation of a mantle of small uniform cells several cells thick covering the surface of the apex. The apex increased in height and the long internode between the last-formed pair of leaf primordia and first pair of microsporophylls formed a short stalk at the base of the cone. The transition of a vegetative apex to a seed cone apex occurred 27 days after initial GA3 treatment and was similar to that for pollen cones. Bract primordia are initiated closer to the summit of the apex and are larger in initial stages than microsporophyll primordia, and longer internodes remain between successive pairs of bracts. Ovule initiation occurs when bracts have just begun upward growth. All microsporophylls, bracts, and ovules are formed during the few weeks after cone initiation and before cones become dormant. No anatomical changes occurred in either cone type during subsequent short-day cold treatment. A return to long-day warm conditions promoted normal cone development. Under natural conditions in the Victoria area, pollen cones are initiated early in June under long days and increasing day length while seed cones are initiated early in July under similar long days but decreasing day length. Development of both pollen and seed cones occurs during long days and decreasing day length. The possible relationship between sexuality of cones, gibberellin, auxin, and day length is discussed.

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.

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.

The pollination mechanism and development after bud burst of cones of Larix laricina

1991 ◽  
Vol 69 (6) ◽  
pp. 1179-1187 ◽  
Author(s):  
G. R. Powell ◽  
Kathleen J. Tosh
Keyword(s):  
Key Words ◽  
Seed Size ◽  
Larix Laricina ◽  
Bud Burst ◽  
Scale Growth ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Cone Development ◽  
Micropylar Canal ◽  
Pollen Cone

Pollen-cone and seed-cone development, from bud burst to maturity, was investigated on Larix laricina (Du Roi) K. Koch in three young plantations. The pollination mechanism was emphasized. Pollen cones grew rapidly to shed pollen, shrivelled, and remained on the trees for a year or more. Pollen was directed to the ovular regions by the bracts of the seed cones. Pollen adhered among papillae on the larger of two integument extensions. Degeneration of the centre of the papillate integument tip caused a collapse that drew pollen in as the papillate rim grew inward. This ingrowth was joined by that of the smaller integument extension, resulting in a sealed tubular structure that enclosed a dry micropylar canal. Pollen was held by the ingrown plug of degenerated tissue as the nucellus tip expanded into the base of the canal. As this occurred, the ovules, with or without pollination, grew to ultimate seed size, and the initially small ovuliferous scales overgrew the bracts. First bract, then ovuliferous-scale growth was associated with a double-sigmoid form of cone elongation. In mature cones the bracts decreased and the ovuliferous scales (except near the tip) increased in size acropetally. Key words: bract, integument, ovuliferous scale, pollen cone, seed cone, tamarack or eastern larch.

Reproductive growth and development in seven provenances of lodgepole pine

1988 ◽  
Vol 18 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Conor O'Reilly ◽  
John N. Owens
Keyword(s):  
Growth And Development ◽  
Reproductive Growth ◽  
Bud Development ◽  
Cone Production ◽  
Growth Increments ◽  
Seed Cone ◽  
Cone Development ◽  
Pollen Release ◽  
The Times ◽  
Pollen Cone

Reproductive growth and development were studied in 1983 in seven provenances of Pinuscontorta Dougl. ssp. latifolia Engelm. growing in a provenance trial near Prince George, B.C. Stages of pollen release and seed-cone receptivity were scored by indices of cone development. Pollen- and seed-cone numbers were estimated and the distribution of seed cones within the upper crown and on annual growth increments of fourth-whorl branches was assessed. Pollen-and seed-cone bud development was followed in sectioned long-shoot buds taken at 2- to 3-week intervals. The times of maximum seed-cone receptivity and pollen release differed slightly among provenances, indicating that there was a high chance of cross-pollination. Differences among provenances in pollen-cone numbers were large, but smaller differences in seed-cone numbers were noted. No mature pollen cones or developing pollen-cone buds were found in the Yukon provenance. Seed-cone production varied with whorl position and was influenced by polycyclic long-shoot development. Potential pollen-cone buds were initiated from May until late June. Pollen cones first differentiated in early to mid July in all provenances. Potential seed-cone apices were noted from mid-June to late July and differentiation occurred in mid-July to early August, depending on provenance. Seed-cone bud development began first in the northern provenances.

Effect of GA3 treatment timing in relation to natural day length on flowering and sex expression in Chamaecyparisnootkatensis

1989 ◽  
Vol 19 (11) ◽  
pp. 1422-1428 ◽  
Author(s):  
R. C. Bower ◽  
S. D. Ross ◽  
B. G. Dunsworth
Keyword(s):  
Treatment Time ◽  
Sex Expression ◽  
Day Length ◽  
Optimal Time ◽  
Bud Development ◽  
Treatment Timing ◽  
Seed Cone ◽  
Specific Stage ◽  
Pollen Cone ◽  
Weekly Dosage

Experiments on field-grown and potted trees investigated the effect of timing of gibberellin A3 treatment in relation to natural day length on flowering and sex expression in Chamaecyparisnootkatensis. When gibberellin A3 treatment began was more important than the number of weekly sprays (two to eight), and the optimal time of treatment was similar for promotion of seed and pollen cone buds. The optimal treatment time was independent of photoperiod or its direction of change, but instead appeared to be related to a specific stage of ontogeny during early development of the bud apex. Trees growing at progressively lower elevations attained this stage earlier in spring, suggesting that the mechanism triggering initiation of bud development involved heat sums. A higher concentration of gibberellin A3 was required to initiate seed cone buds (200 mg•L−1) than pollen cone buds (100 mg•L−1), and the average weekly dosage was more important than whether gibberellin A3 was applied weekly or biweekly. Young, potted trees within a greenhouse flowered more profusely than larger but similarly treated field-grown trees, indicating that the species is a good candidate for containerized seed orchards.

Structure and development of shoots in Cytisus scoparius

1990 ◽  
Vol 68 (12) ◽  
pp. 2576-2582 ◽  
Author(s):  
Tian Su Zhou ◽  
Noboru Hara
Keyword(s):  
Growing Season ◽  
Lateral Branch ◽  
Main Axis ◽  
Leaf Primordia ◽  
Axillary Meristem ◽  
Cytisus Scoparius ◽  
Lateral Branches ◽  
Winter Buds ◽  
The Relationship ◽  
Characteristic Manner

The vegetative winter bud of Cytisus scoparius Link contains about nine leaf primordia. It grows into a main axis during the current growing season. At the end of the growing season, a shoot system consisting of a main axis and many lateral branches is formed. The lateral branch originates as a primordium when winter buds expand in spring, from the axil between the sixth and eighth leaves (numbered from the base of the bud), following which the succeeding primordia of branches appear sequentially. These lateral primordia continue to extend synchronously with the extension of the main axis during the growing season. By the end of the growing season, the lateral branches have reached various lengths and are arranged in a somewhat characteristic manner on the main axis; the relatively long branches are often located on the portions with ternately compound leaves and are associated with the vigorous elongation of the main axis. The relationship between the growth of the lateral branches and the main axis is discussed. Key words: axillary meristem, Cytisus, proleptic shoot, sylleptic shoot.

Cone and seed development in a wind-pollinated, western hemlock (Tsugaheterophylla) clone bank

1990 ◽  
Vol 20 (9) ◽  
pp. 1432-1437 ◽  
Author(s):  
Anna M. Colangeli ◽  
John N. Owens
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Western Hemlock ◽  
Factors Affecting ◽  
Ovule Abortion ◽  
Cross Pollination ◽  
Seed Cone ◽  
Cone Development ◽  
Empty Seed ◽  
Pollen Cone

Seed and seed-cone development were observed in a wind-pollinated western hemlock (Tsugaheterophylla (Raf.) Sarg.) clone bank in 1983 and 1986. Seed efficiency, the number of filled seed per cone divided by the seed potential, averaged 64% for 58 wind-pollinated clones in 1983 and 20% for 38 clones in 1986. Based on anatomical observations and cone dissections, seed losses resulted from pre- and post-pollination ovule abortion, insufficient pollen, no fertilization, and embryo degeneration. Prepollination ovule abortion, identified by small, flat seed in mature cones, contributed to 11 and 14% reduction in filled-seed yield in 1983 and 1986, respectively. Full-sized but empty seed (lacking an embryo) accounted for 25 and 66% reduction in potential seed yield in the 2 years, respectively. In 1983, 98% of the clones bore a pollen-cone crop compared with 53% in 1986. Lack of fertilization resulting from a limited pollen supply was believed to be the main cause for the lower filled-seed yield in 1986. The effect of wind and controlled (cross-) pollination on filled-seed production was determined for 16 clones in 1983. Seed efficiency after wind and cross-pollination averaged 65 and 69%, respectively. Seed potential averaged 34 and 31 ovules per cone for the wind- and cross-pollinated cones, respectively. Prepollination ovule abortion averaged 12 and 14%, respectively. From anatomical observations, the full-sized but empty seed resulted from lack of fertilization and embryo degeneration. The different factors affecting final filled-seed yield are discussed in terms of their effect on seed production.

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.

Challenges facing Chamaecyparis nootkatensis seed orchards: low seed production, pollen-cone abortion, self-pollination, and accelerated embryo development

2002 ◽  
Vol 32 (8) ◽  
pp. 1411-1419 ◽  
Author(s):  
Erika D Anderson ◽  
John N Owens ◽  
Anna M Colangeli ◽  
John H Russell
Keyword(s):  
Seed Production ◽  
Embryo Development ◽  
Reproductive Development ◽  
Seed Orchard ◽  
The Other ◽  
Natural Stand ◽  
Chamaecyparis Nootkatensis ◽  
Self Pollination ◽  
Cone Development ◽  
Pollen Cone

Seed orchard production of Chamaecyparis nootkatensis (D. Don) Spach seed faces several challenges including low seed production, pollen-cone abortion, self-pollination, and accelerated reproductive development. In a seed orchard study in 1988 and 1989, approximately eight seeds were produced per cone, but only one to three seeds per cone contained viable embryos. Pollen-cone abortion in 21 clones ranged from 6 to 87% in 1989–1990 and from 0 to 6% in 1990–1991. A bud mite, identified as Trisetacus chamaecypari Smith, was consistently associated with pollen-cone abortion in two orchard locations. This mite may be the cause or simply a symptom of unhealthy pollen cones. In a pollination study involving wind, self, and cross pollinations on five clones, self-pollinated cones had significantly fewer seeds containing embryos (4%) compared with the other treatments (28–33%). Pollen-cone development at a seed orchard occurred in July and August 1990 and was comparable with natural stand phenology. However, embryo development was significantly accelerated, with embryos at a seed orchard substantially larger than embryos at the natural stand at comparable times.

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