Studies of Development in Long Shoots and Short Shoots of Ginkgo Biloba L. Iv. Growth Habit, Shoot Expression and the Mechanism of Its Control

Gunckel, James E.; Thimann, Kenneth V.; Wetmore, Ralph H.

doi:10.1002/j.1537-2197.1949.tb05265.x

Cited by 38 publications

(21 citation statements)

References 6 publications

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“…"Vigorous" or fast-growing plants do in fact produce more branches, as has been noticed by Mitchell (1953) in the growth of ryegrass (Lolium sp. ), and by Gunckel, Thimann, and Wetmore (1949) in the outgrowth of short-shoot buds on young Ginkgo trees. Similarly, studies of the influence of nutrition on apical dominance (Gregory and Veale, 1957;Champagnat and Dalzon, 1958;Hugon, 19;')8, 1960 show that nutrients play a major role in the process because their addition causes an increase in the number of branches formed.…”

Section: Alcohol 50%mentioning

confidence: 96%

The Role of Auxins and Cytokinins in the Release of Buds From Dominance

Sachs

Thimann

1967

American J of Botany

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292

129

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The paper deals with the general problem of the physiological basis of branching, and the roles of known and unexplored factors in sensitivity to apical dominance. It is shown that when pea seedling shoots are completely or partially inhibited by other shoots on the same plant auxin can promote their elongation, even though it does not have this effect on inhibited buds. This influence of auxin is only exerted on internodal elongation and not on apical growth. When kinetin in a solution of alcohol and carbowax is applied directly to the lateral buds of pea seedlings, it releases them from inhibition by the growing apex. It is shown that the role of alcohol in this solution is to act as a surfactant, permitting good contact with the buds, while that of carbowax, being hygroscopic, is to maintain a thin film of solution over the buds. Buds thus released from apical dominance by kinetin do not elongate as much as do uninhibited control buds. Such kinetin‐treated buds can, however, be made to elongate normally by the application of auxin locally to their apices. It is concluded that growing shoots are relatively insensitive to correlative inhibition because they synthesize two types of growth substances, namely, auxin, which antagonizes the inhibitory effect on internodal elongation, and cytokinins, which permit the apex itself to develop. In the discussion it is brought out that many cases of branching, which appear at first to bear little relation to one another, can be understood on the basis of two principles, namely: (1) Any reduction in the growth rate of a dominant apex reduces its inhibitory effect on other apices, and (2) once an apex starts growing it becomes less sensitive to inhibition by other apices These generalizations and the experimental results are tentatively interpreted in terms of an interaction between the syntheses of auxin and of cytoldnin.

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Section: Alcohol 50%mentioning

confidence: 96%

The Role of Auxins and Cytokinins in the Release of Buds From Dominance

Sachs

Thimann

1967

American J of Botany

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292

129

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“…As indicated above, some workers (Sachs, 1966;Morris, 1977;Li and Bangerth, 1999) have reported partial restoration effects of apical control by exogenous auxin treatments of decapitated dominant shoots even though no evidence has been found of auxin movement into the dominated shoot. Gunckel, Thimann, and Wetmore (1949) reported on what appears to be a type of apical control study on 3-yr-old Ginkgo seedlings. They found that 1% NAA (naphthaleneacetic acid) applied to the cut stem surface inhibited short lateral shoots from growing into long shoots.…”

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confidence: 99%

Is auxin the repressor signal of branch growth in apical control?

Cline¹,

Sadeski²

2002

American J of Botany

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"Apical control" is the repression of branch growth by a higher dominating branch or shoot. There has been some confusion in the literature concerning the meaning and causal mechanisms of this correlative phenomenon with those of "apical dominance," which term is often used in a strict sense to connote the repression of the initiation of axillary bud outgrowth by an active shoot apex. Although the term "apical control" is most commonly employed with respect to woody species, this phenomenon also widely occurs in herbaceous plants. Because of the strong evidence for a role of auxin as a repressor signal in apical dominance and partly because of this lack of distinction in terminology, a similar role for auxin in apical control is often assumed in spite of the obvious acropetal auxin transport difficulty and the lack of direct evidence for the acropetal transport of any inhibitor influence. In the present study with the herbaceous Ipomoea nil, it has been clearly demonstrated that while exogenous auxin (1% NAA) strongly restores apical dominance in the Thimann-Skoog experiment, auxin treatments to decapitated dominant shoots do not, in any observable way, restore apical control in lower dominated branches. Hence, in this fast-growing species, the hypothesis for the role of auxin as a repressor signal for apical control is not supported.

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“…It elucidates the statement that all the buds of Larix appear at first to form 'short' shoots, some of which later grow out into 'long' shoots (Biisgen and Munch, 1929). However, in Larix, 'long' growth appears as a unified growth process, unlike the two stages reported in Cinkgo by Gunckel, Thimann and Wetmore (1949).…”

Section: (D) Bud Expansionmentioning

confidence: 72%

SOME ASPECTS OF THE DEVELOPMENTAL ANATOMY OF THE‘LONG’SHOOT IN LARIX DECIDUA MILL., WITH PARTICULAR REFERENCE TO SEASONAL PERIODICITY*

Frampton

1960

New Phytologist

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Summary A description is given of the structure and behaviour of the terminal bud of the ‘long’ shoot in Larix decidua Mill, throughout the yearly growth cycle. Within the bud two regions of the new growth, the ‘axial’ and the ‘fascicular’, may be recognized. The capacity of a bud to grow into a ‘long’ shoot depends on the presence within it of the ‘axial’ portion, and is thus determined in the season prior to the opening of the bud. Weaker branches of the tree bear smaller terminal buds in which the ‘axial’ portion is reduced or absent.

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Studies of Development in Long Shoots and Short Shoots of Ginkgo Biloba L. Iv. Growth Habit, Shoot Expression and the Mechanism of Its Control

Cited by 38 publications

References 6 publications

The Role of Auxins and Cytokinins in the Release of Buds From Dominance

The Role of Auxins and Cytokinins in the Release of Buds From Dominance

Is auxin the repressor signal of branch growth in apical control?

SOME ASPECTS OF THE DEVELOPMENTAL ANATOMY OF THE‘LONG’SHOOT IN LARIX DECIDUA MILL., WITH PARTICULAR REFERENCE TO SEASONAL PERIODICITY*

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