scholarly journals Timing of Evocation and Development of Flowers in Pharbitis Nil

1969 ◽  
Vol 22 (3) ◽  
pp. 559 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Shoot Apex ◽  
Dark Period ◽  
Leaf Primordium ◽  
Axillary Buds ◽  
Axillary Bud ◽  
Pharbitis Nil ◽  
Main Shoot ◽  
Floral Evocation

When P. nil seedlings were exposed to a single inductive dark period, the main shoot apex and the lowest axillary bud which had not differentiated more than one leaf primordium underwent floral evocation within about 12 hr of the end of the dark period. The higher axillary buds appeared to be evoked in acropetal sequence over the following 2 days at 28�C, or 4 days at 21�C.

The Acceleration of Primordium Initiation as a Component of Floral Evocation in Lolium temulentum L

1996 ◽  
Vol 23 (5) ◽  
pp. 569 ◽  
Author(s):  
LT Evans ◽  
C Blundell
Keyword(s):  
Shoot Apex ◽  
Floral Development ◽  
Growth Retardant ◽  
Leaf Primordium ◽  
Essential Component ◽  
Lolium Temulentum ◽  
Long Day ◽  
External Sign ◽  
Floral Evocation

An acceleration of leaf primordium initiation by the shoot apex frequently follows floral evocation, but after varying intervals. The purpose of the experiments reported here was to define more closely the relation between this reduction of the plastochron and floral evocation, using the long day (LD) plant Lolium temulentum grown under closely controlled conditions.The acceleration begins at floral evocation, on the day after the first LD exposure, and increases after exposure to additional LDs. However, plants too young to be florally evoked by one LD nevertheless manifested an acceleration of primordium initiation, so the acceleration alone is not sufficient for evocation. Single applications of highly florigenic gibberellins (GAs), such as GA5, also accelerate the initiation of primordia and floral development, more so than does the weakly florigenic GA1. By contrast, single applications of the growth retardant Trinexapac-ethyl (CGA 163'935) to plants given one LD largely prevented the acceleration of primordium initiation but without inhibiting floral development. Thus, although the acceleration of primordium initiation by LD or by GA application is the first external sign of floral evocation in L. temulentum, it is neither a sufficient nor an essential component of it.

DIFFERENTIAL RNA SYNTHESIS IN THE SHOOT APEX OF PHARBITIS NIL DURING FLORAL EVOCATION

1991 ◽  
Vol 78 (3) ◽  
pp. 401-407
Author(s):  
Bruce A. Bonner ◽  
Ernest M. Gifford ◽  
Nu-May Ruby Reed
Keyword(s):  
Shoot Apex ◽  
Rna Synthesis ◽  
Pharbitis Nil ◽  
Floral Evocation

scholarly journals IAA in the control of photoperiodic flower induction of Pharbitis nil chois

2014 ◽  
Vol 64 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Halina Kulikowska-Gulewska ◽  
Mariusz Cymerski ◽  
Joanna Czaplewska ◽  
Jan Kopcewicz
Keyword(s):  
Shoot Apex ◽  
Dark Period ◽  
Floral Induction ◽  
Pharbitis Nil ◽  
Flower Bud ◽  
Long Distance ◽  
Polar Transport ◽  
Bud Formation ◽  
Flower Bud Formation ◽  
Auxin Polar Transport

The endogenous content of IAA in the cotyledons of <i>Pharbitis nil</i> is low before and during the first half of the inductive 16-h-long dark period. From the 8th to the 12th hour the level of IAA increased and then again was going down at the end of a dark period. Exogenous IAA applied to the cotyledones before and during the first half of the inductive dark period inhibits flower bud formation. The application of IAA to shoot apex also resulted in the inhibition of flowering. Experiments with TIBA, an auxin polar transport inhibitor, and PCIB, an auxin action inhibitor, have shown that auxin polar transport in cotyledones and long-distance auxin transport from cotyledones to shoot apex play an important role in IAA inhibition of flower bud formation. It suggests that auxins play their role not only at the level of floral induction in cotyledones, but also in the later events of floral evocation and differentiation in shoot apex.

scholarly journals The Effects of Growth Regulators on Shoot Propagation and Rooting of Vitis Following in Vitro Axillary Bud and Shoot Apex Culture

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 516C-516
Author(s):  
Handan Büyükdemirci ◽  
Paul E. Read
Keyword(s):  
Shoot Apex ◽  
Shoot Growth ◽  
Shoot Proliferation ◽  
Multiple Shoots ◽  
Multiple Shoot ◽  
Axillary Buds ◽  
Axillary Bud ◽  
Ms Medium ◽  
Axillary Bud Culture

Axillary buds of `Valiant' grapevine (Vitis spp.) grown in vitro were transferred onto Murashige and Skoog (MS) medium supplemented with different cytokinin and auxin combinations and concentrations. It was found that culture medium caused statistically important differences in number of nodes, number of fully expanded leaves, number of multiple shoots, number of roots, and length of shoots. MS medium supplemented with 1.0 mg BA/liter in combination with 0.01 mg NAA/L was found to be the best medium for shoot growth and callus production. MS medium supplemented with the combination of 0.5 mg BA/L and 0.01 mg NAA/L was the best medium for explant rooting. The medium containing BA and NAA encouraged better shoot growth than those containing BA alone. When the concentration of BA in the medium was increased, multiple shoot proliferation and teratological structures of explants increased, but the number of small leaves and length of internode decreased. Axillary bud culture led to better shoot growth than was found for shoot apex culture. The presence of leaves positively affected shoot growth from axillary buds. Also placing the axillary buds horizontally onto the medium gave better shoot proliferation and growth than placing them vertically.

The causes of the bud eccentricity and the large divergence angles between leaves in Cucurbitaceae

1965 ◽  
Vol 250 (762) ◽  
pp. 53-77 ◽  
Keyword(s):  
Tangential Direction ◽  
Leaf Primordium ◽  
Axillary Buds ◽  
Axillary Bud ◽  
Space Filling ◽  
The Third ◽  
Young Seedling ◽  
Made In

In Cucurbitaceae the axillary buds are eccentric, being much displaced in the anodic or up-hill direction of the genetic leaf spiral: also the angles between successive leaves are unusually large. In the young seedling the leaf spiral and the bud eccentricity both start with the third leaf from the base. If a radial vertical cut of some little depth is made in the apex at the kathodic side of P 1 , the youngest leaf primordium, or of I 1 , the next primordium due to arise, the bud of the P 1 or I 1 is often median or nearly so. Also, if P 1 or I 1 is isolated from the apex with a vertical cut made in the tangential direction and is then extirpated, the bud of the next primordium, I 1 or I 2 , is often subeccentric or nearly median. But shaving down the upstanding part of P 1 flush with the apex, or preventing with shallow cuts P 1 or its bud or both from developing does not diminish the eccentricity of any subsequent bud. It is concluded that an axillary bud is made anodic by some repelling influence, perhaps a hormone, which originates from an older leaf primordium and travels in the anodic direction of the leaf spiral. This influence is interrupted by a cut of moderate depth in the apex, but not by a very shallow cut. The changes in the positions of certain younger leaves due to the formation of median or nearly median buds after these operations strongly support an explanation of the large angles between successive leaves based on a space-filling theory of phyllotaxis. This explanation is that the position in which any leaf n is determined is displaced in the anodic direction by the anodic axillary bud of leaf n — 3, which encroaches from the kathodic side upon the space available for n between n — 3 and n — 2. When the bud of n — 3 is median or nearly so, the position of n is much less far anodic. The repelling influence that makes the buds anodic is further discussed in relation to the course of the conducting strands and other relevant facts.

scholarly journals Experiments on growth and inhibition. I.—The increase of inhibition with distance

1931 ◽  
Vol 108 (756) ◽  
pp. 209-223 ◽  
Keyword(s):  
Pisum Sativum ◽  
Axillary Buds ◽  
Axillary Bud ◽  
Inhibiting Effect ◽  
Different Ages ◽  
Young Leaves

Experiments were recently reported showing that, in young seedlings of Pisum sativum , the complete inhibiting effect which the shoot exerts upon its axillary buds comes entirely or almost entirely from three or four of its developing leave acting together (6). A single developing leaf was found usually to inhibit only partially—that is to say, sufficiently to delay the growth of an axillary bud below it, but not to check it completely. The strength of this partial inhibiting effect was measured by the retardation of the outgrowth of the axillary buds of the first or lowest leaf, as compared with their growth in completely defoliated controls. Comparisons were further made of the inhibiting effects of single young leaves of equal sizes near the apex in seedlings of different ages and heights, and it was found that in very young short seedlings the inhibiting effect was very slight or inappreciable, although in seedlings of a height of about 30 mm. or more (but still possessing well filled cotyledons) the effect was strong.

The shoot apex and the ontogeny of axillary buds in Cuminum cyminum L

1969 ◽  
Vol 17 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Shah ◽  
K Unnikrishnan
Keyword(s):  
Shoot Apex ◽  
Peripheral Zone ◽  
Axillary Bud ◽  
Vegetative Shoot ◽  
Apical Position ◽  
Leaf Initiation ◽  
Axillant Leaf ◽  
Meristematic Activity ◽  
Vegetative Shoot Apex ◽  
The One

The structure and plastochronic changes of the shoot apex, and the origin, development, procambialization, and vascular relationships of the axillary bud in Cuminum cyminium were investigated. Pre-leaf initiation, leaf initiation, and post-leaf initiation phases of the shoot apex are identified. The inflorescence is axillary. During flowering the main vegetative shoot apex is semispherical, stratified, and devoid of any distinction between the central and peripheral zones. The vegetative axillary bud is differentiated from the peripheral zone of the shoot apex at the second node. It is delimited by an arcuate shell zone which helps in changing the apical position of the bud to foliar. The emergence of the bud is effected by the meristematic activity of tunica and corpus cells. A single prophyll is formed at right angles to the axillant leaf. Usually the bud trace procambium is differentiated during prophyll initiation. Occasionally it may be seen earlier, but not in connection with the earliest visible bud meristem. There are four to six strands of the bud trace directly interconnecting not only the strands of the prophyll and axillant leaf traces but also those of the second or sometimes even the third bud leaf and the axillant leaf. The bud trace procambial connection is formed by basipetal and acropetal differentiation of procambium in which the bud meristem cells and vacuolated ground meristem cells below the bud are involved. The cells of the peripheral zone of the bud apex below the prophyll primordium procambialize in a basipetal direction. As a continuation from the strand of the axillant leaf trace, the adjacent vacuolated ground meristem cells below the bud acropetally differentiate into procambial cells in the direction of the basipetal procambium and they make connection with it. All the strands of the bud trace are not simultaneously developed. The vegetative and inflorescence buds show varying vascular relationships between the strands of the leaf traces and those of the bud traces. The node differentiated during the vegetative phase of the plant is trilacunar and the one formed at flowering time is tetra- or pentalacunar. The nature and number of bud trace strands, however, suggest fundamental similarities between vegetative and inflorescence buds.

Disruption by Temperature of Floral Evocation and Cell-Cycling in the Shoot Apical Meristem of Helipterum roseum

1990 ◽  
Vol 17 (6) ◽  
pp. 629 ◽  
Author(s):  
KV Sharman ◽  
M Sedgley ◽  
D Aspinall
Keyword(s):  
Cell Cycle ◽  
Steady State ◽  
Shoot Apex ◽  
Apical Meristem ◽  
Shoot Meristem ◽  
Cycle Duration ◽  
Floral Initiation ◽  
H 41 ◽  
Cell Cycling ◽  
Floral Evocation

Flowering is inhibited in plants of Helipterum roseum grown under constant 25°C temperature conditions with a 12 h photoperiod and irradiance of 250 W m-2, but not at a constant temperature of 20°C. Floral inhibition was investigated by transferring plants between the two temperature con- ditions at different times to determine the morphological stage of inhibition, and by investigating cell-cycling at the shoot apex at the two temperatures. Floral initiation in Helipterum roseum was inhibited if the temperature increase from 20 to 25°C occurred at the doming of the apical meristem, and was delayed when the increase occurred at the initiation of involucral bracts. Steady-state cell-cycling was observed in the shoot meristem at 20°C and the cell-cycle duration was estimated at the morphological stages of large vegetative meristem, doming of the meristem and initiation of the involucral bracts. The length of the cell-cycle at these stages was 64 h, 41 h and 47 h respectively. Steady-state cell-cycling was not observed in shoot apical meristems at 25°C, and the meristem did not undergo the floral transition. It is concluded that the stage of commitment to flower is the initiation of involucral bracts, and that floral initiation is inhibited at 25°C by the loss of steady-state cell-cycling at the shoot apex.

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