Promotion of flowering in western hemlock by gibberellin A4/7 applied at different stages of bud and shoot development

1989 ◽  
Vol 19 (8) ◽  
pp. 1051-1058 ◽  
Author(s):  
John N. Owens ◽  
Anna M. Colangeli
Keyword(s):  
Effective Treatment ◽  
Shoot Elongation ◽  
Shoot Development ◽  
Western Hemlock ◽  
Bud Burst ◽  
Cone Production ◽  
Seed Cone ◽  
Pollen Cone ◽  
Vegetative Bud

Cone buds were induced on container-grown and field-grown western hemlock (Tsugaheterophylla (Raf.) Sarg.) clones during a 3-year period to study the effects of time and duration of gibberellin A4/7 treatment on cone induction, sexuality of cones, and to relate these results to bud and shoot development. The most effective treatment times preceded anatomical differentiation. The most abundant pollen cones and seed cones were produced when trees were sprayed with gibberellin A4/7 before vegetative bud burst and early shoot elongation. Two to three weekly gibberellin A4/7 applications starting at preswollen and swollen-bud stages were adequate for pollen-cone production. Pollen-cone production decreased when the applications were started at vegetative bud burst or during early shoot elongation. A minimum of three weekly applications were required for seed-cone production, and applications were equally effective when started at preswollen, swollen, and vegetative bud burst stages. Seed-cone production decreased when three weekly applications were started during early shoot elongation; however, this was overcome by increasing the number of applications.

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.

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.

Timing of gibberellin A4/7 application for cone production in potted black spruce grafts

1991 ◽  
Vol 21 (7) ◽  
pp. 1137-1140 ◽  
Author(s):  
Rong H. Ho
Keyword(s):  
Black Spruce ◽  
Foliar Spray ◽  
Shoot Elongation ◽  
Bud Break ◽  
Bud Burst ◽  
Lateral Shoot ◽  
Cone Production ◽  
Best Response ◽  
Seed Cone ◽  
Vegetative Bud

Potted 5-year-old grafts of black spruce (Piceamariana (Mill.) B.S.P.) growing in either a heated greenhouse or an outdoor holding area were sprayed weekly at 200 mg•L−1 gibberellin A4/7 for various durations and timings. The application began 1 to 6 weeks after vegetative bud break and continued until the end of lateral shoot elongation. Sprayings ended at the same time for all treatments, about 1 week before leaf primordial differentiation on the shoot apices. The best response in seed-cone production occurred when application began 2 weeks after bud break (midstage of rapid shoot elongation) and continued for 5 weeks; treatments were also effective when applications began 3 weeks after bud break or earlier and continued for 4 to 6 weeks. Treatments initiated later (4 to 6 weeks after bud break) were not effective. Grafts kept outdoors produced more seed cones than those kept indoors. The effects on cone production of gibberellin A4/7 application at four different concentrations were compared by spraying for 6 weeks, beginning 1 week after vegetative bud burst. Gibberellin A4/7 at 200 mg•L−1 was the lowest foliar spray concentration found to be effective in promoting seed-cone 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.

Effects of stem injections of gibberellin A4/7 and paclobutrazol on sex expression and the within-crown distribution of seed and pollen cones in black spruce (Picea mariana)

1998 ◽  
Vol 28 (5) ◽  
pp. 641-651 ◽  
Author(s):  
Ronald F Smith
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Sex Expression ◽  
Bud Burst ◽  
Seed Orchards ◽  
Adjunct Treatment ◽  
Cone Production ◽  
Pollen Cone ◽  
Dose Dependent ◽  
Vegetative Bud

Two experiments in black spruce (Picea mariana (Mill.) BSP) seedling seed orchards were established to determine if a stem injection of paclobutrazol (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl) could be used as an adjunct treatment to increase the efficacy of stem injections of gibberellins A4 and A7 (GA4/7). Trees received a single injection of GA4/7 and (or) paclobutrazol shortly after vegetative bud burst. There was a dose-dependent but nonlinear increase in the production of cones of both sexes in response to stem injections of either GA4/7 or paclobutrazol. The optimum rate of GA4/7 for stimulating pollen-cone production was 3.3 mg, whereas the most seed cones were induced on trees receiving 11 mg. The sex ratio (number of seed cones/number of pollen cones) increased with the rate of GA4/7 applied. Injecting paclobutrazol also promoted cones of both sexes equally, resulting in sex ratios comparable with that of the control trees. Treatments did not affect the total numbers of buds (vegetative, latent, and cone) produced. Seed- and pollen-cone buds occurred in positions that would have otherwise developed vegetatively and become latent, respectively. The mechanisms whereby paclobutrazol could affect flowering in black spruce are discussed. The use of paclobutrazol as an adjunct to GA4/7 treatments in black spruce seedling seed orchards appears effective, practical, and safe.

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 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.

Effects of cultural treatments and gibberellin A4/7 on flowering of container-grown European and Japanese larch

1995 ◽  
Vol 25 (2) ◽  
pp. 184-192 ◽  
Author(s):  
J.J. Philipson
Keyword(s):  
Heat Treatment ◽  
Shoot Elongation ◽  
Japanese Larch ◽  
Main Stem ◽  
Root Pruning ◽  
Drought Treatment ◽  
Cone Production ◽  
Seed Cone ◽  
Maximum Temperatures ◽  
Pollen Cone

Gibberellin A4/A7 (GA4/7) was injected into the main stem of container-grown Larixdecidua Mill, and Larixkaempferi (Lamb.) Carr. grafts, using different quantities and times of application of GA4/7 and applying it both alone and in combination with heat, drought, girdling, or root pruning. The GA4/7 did not increase flowering, and girdling and root pruning alone were ineffective. In contrast, flowering was substantially increased when grafts were placed in a polythene house from May (beginning of long-shoot elongation) to June or early September (depending on experiments), in three separate experiments, with mean maximum temperatures of 29–30 °C. This heat treatment significantly increased both seed- and pollen-cone production, and drought treatment significantly increased seed-cone production. Treatment means of up to 143 seed cones and between 250 and 1000 pollen cones per graft, on 1.5 m tall grafts, were observed. In one experiment heat treatment in the polythene house did not increase flowering. In that experiment vegetative buds reflushed during treatment in the polythene house, which could have reduced potential flowering sites; the reflushing may have been associated with needle damage possibly caused by higher than usual temperatures, of over 40 °C.

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.

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.

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