Effect of heat and its timing within a polyhouse on flowering in potted Douglas-fir trees

1992 ◽  
Vol 22 (5) ◽  
pp. 736-739 ◽  
Author(s):  
Stephen D. Ross
Keyword(s):  
Heat Treatment ◽  
Low Temperatures ◽  
Shoot Elongation ◽  
Douglas Fir ◽  
Naphthaleneacetic Acid ◽  
Bud Burst ◽  
Rooted Cuttings ◽  
Ambient Temperatures ◽  
Temperature Regimen ◽  
Vegetative Bud

Female and male flowering in potted Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) rooted cuttings treated with gibberellin A4/7, with and without naphthaleneacetic acid, were inhibited by heat treatment in a closed polyhouse with a temperature regimen of 28:15 °C (day:night) relative to the flowering achieved in an open-sided polyhouse with near-ambient temperatures. The effect was greater for an early heat treatment (from vegetative bud burst to end of shoot elongation), which bracketed cone-bud differentiation, than for a following late heat treatment of similar duration. Effects of the early plus late heat treatments were additive. It was not the objective of this study to determine the optimal temperature regimen for flowering. However, other than possibly in locations where low temperatures prevail during cone-bud differentiation in spring, heat treatment within a polyhouse appears to be neither a necessary nor desirable adjunct to gibberellin A4/7 for promotion of flowering in potted Douglas-fir.

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.

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.

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.

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 Sitka spruce. I. Annual growth cycle of vegetative buds and shoots

1976 ◽  
Vol 54 (3-4) ◽  
pp. 313-325 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Early Period ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Picea Sitchensis ◽  
Leaf Primordia ◽  
Annual Growth ◽  
Bud Burst ◽  
Leaf Initiation ◽  
Number Of Leaves ◽  
Vegetative Bud

Vegetative apices of Picea sitchensis (Bong.) Carr. were studied throughout the annual growth cycle. Apices became mitotically active late in March and the shoot axis and leaf primordia elongated causing the bud to swell. New axillary apices were initiated in mid-April and the terminal apex and new axillary apices initiated bud scales until early in July. Vegetative bud burst occurred early in June and shoot elongation was completed by mid-July. The end of shoot elongation coincided with the onset of leaf initiation. The change from bud-scale to leaf initiation was characterized by a period of increased mitotic activity and rapid apical growth. About half of the final number of leaves were initiated during the early period of rapid leaf initiation. The remaining leaf primordia were initiated more slowly over the next 3 months. Buds became dormant by mid-November.

Enhancement of shoot elongation in Douglas-fir by gibberellin A4/7 and its relation to the hormonal promotion of flowering

1983 ◽  
Vol 13 (5) ◽  
pp. 986-994 ◽  
Author(s):  
Stephen D. Ross
Keyword(s):  
Stem Elongation ◽  
Maximum Growth ◽  
Shoot Elongation ◽  
Early Spring ◽  
Douglas Fir ◽  
Threshold Concentration ◽  
Physiological Age ◽  
Growth Enhancement ◽  
Bud Burst ◽  
Treatment Timing

The enhanced stem elongation that frequently accompanies the gibberellin A4/7 (GA4/7) promotion of flowering in Pinaceae species was investigated for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) vegetative propagules in relation to their physiological age, GA4/7 concentration, and treatment timing. Maximum growth enhancement, but marginal promotion of flowering (males and females), occurred when GA4/7 was applied in early spring before vegetative buds had begun to swell. In contrast, shoot elongation was only slightly enhanced when GA4/7 treatment was timed (vegetative bud burst ±4.5 weeks) to bracket the critical period for effecting differentiation of axillary primordia into cone buds. Also, the GA4/7 concentration optimal for flowering was supraoptimal for shoot elongation, and the growth response to GA4/7 decreased, whereas the flowering response increased, with increasing physiological age of the propagules (scions 4–45 years old). These findings are consistent with a hypothesis that exogenous GA4/7 is first utilized for vegetative growth processes, increased flowering occurring only after a threshold concentration is reached.

The influence of high ambient temperatures and plane of nutrition on wool growth rates of tropical sheep

1975 ◽  
Vol 15 (77) ◽  
pp. 753 ◽  
Author(s):  
KW Entwistle
Keyword(s):  
Heat Treatment ◽  
Treatment Period ◽  
Growth Rates ◽  
Temperature Treatment ◽  
Wool Production ◽  
Ambient Temperatures ◽  
Treatment Groups ◽  
Wool Growth ◽  
Temperature Regimen ◽  
Quality Diet

The wool production of two groups of tropical Merino sheep subjected to a simulated summer circadian temperature regimen, and fed either high or low quality diets, was compared with that of two other groups under similar nutritional conditions but held at prevailing winter ambient temperatures. The nutritional treatments were imposed for the duration of the experiment; the temperature treatments consisted of a. pre-experimental period of three weeks in which all groups were held at prevailing ambient temperatures b. heat adaptation period of one week in which the heat treatment groups were subjected to gradual increases in the circadian temperature regimen c. heat treatment period of three weeks in which the heat treatment groups were exposed to a circadian temperature regimen in which air temperatures were in excess of 38�C for approximately 7 hours day-1d. post heat treatment period of three weeks in which all groups were held at prevailing ambient temperatures. Temperature treatment had no effect on feed intake or liveweight gain; however, intakes progressively decreased in groups on the low quality diet with a similar decrease in liveweight. Wool growth rates were unaffected by temperature treatment, but were significantly lower in animals on the low quality diet. The possible significance of these results to the wool production of tropical sheep is discussed.

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 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.

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