Shoot development in Betula papyrifera. II. Comparison of vegetative and reproductive short-shoot growth

1983 ◽  
Vol 61 (12) ◽  
pp. 3066-3071 ◽  
Author(s):  
J. Cartey Caesar ◽  
Alastair D. Macdonald

Short shoots of Betula papyrifera Marsh, may be vegetative or reproductive. The latter bear a female inflorescence. Early flushing and rapid growth of short-shoot buds depend on the age and position of the short shoot. Axillary short-shoot buds flush later than 2- to 4-year-old short-shoot terminal buds, which in turn flush later than 5- to 10-year-old shoots. Mean relative growth rate (RGR) of 5- to 10-year-old short-shoot buds is greater than that of younger short-shoot buds. It is suggested that older short-shoot buds are relatively autonomous and that the flushing long shoot exhibits an inhibitory influence on the proximal axillary buds and possibly on young short-shoot terminal buds. Reproductive short shoots differ from vegetative short shoots in that they have lower leaf area ratios and leaf RGR, higher specific leaf area, smaller leaf areas, and fewer side nerve pairs and they grow more in length than in width. These findings are related to reproductive cost. The developing inflorescences act as preferred "sinks" for resource allocation.

1983 ◽  
Vol 61 (12) ◽  
pp. 3049-3065 ◽  
Author(s):  
Alastair D. Macdonald ◽  
D. H. Mothersill

Buds and developing branches of Betula papyrifera were collected weekly from mature trees during three successive growing seasons. Material was prepared to show stages of bud inception, development, and flushing and female inflorescence inception. Short shoots develop from (i) proximal axillary buds on long shoots (ii) short-shoot terminal buds, or (iii) axillary buds on flowering short shoots. An axillary bud apex forms a terminal bud after bud burst. An axillary bud possesses one outer rudimentary leaf, but all other short-shoot buds have three outer rudimentary leaves. All short-shoot buds possess, in addition, one–three embryonic foliage leaves and, distally, three primordial rudimentary leaves which form the outermost appendages of the succeeding terminal bud. Rudimentary leaf stipules form the cataphylls. Foliage leaf primordia are initiated in May – early June and rudimentary leaves arise in late June – July. If a bud apex is initiated in year n, female inflorescence induction occurs in late June of year n + 1 or any succeeding year. An axillary bud develops on a short shoot as a consequence of flowering; it is initiated concurrently with inflorescence development and its development is completed during flowering and seed maturation. Short- and long-shoot buds can be distinguished, upon dissection, in mid-July when buds are forming. Hence, determination of potential long and short shoots occurs the year before bud burst.


1984 ◽  
Vol 62 (3) ◽  
pp. 446-453 ◽  
Author(s):  
J. Cartey Caesar ◽  
Alastair D. Macdonald

Postflush observations on shoots of Betula papyrifera Marsh. indicated that long and short shoots differ in a range of morphological characteristics. Long shoots developed from distal axillary buds and short shoots developed from proximal axillary buds on the previous year's long shoots. Consequently, the potential of a bud to develop into a long shoot decreased basipetally. Potential long-shoot buds had higher bud-relative growth rates, stem-relative growth rates, leaf-relative growth rates, and stem dry weights during the course of postflush growth. Changes in leaf thickness, expressed in terms of specific leaf area and specific leaf weight, indicated that long shoots temporarily had thinner leaves than did short shoots a few weeks after flushing. Net assimilate requirements in long shoots for late leaf and internodal expansion may explain these observations. Nearing maturity, long-shoot early leaves became thicker, possibly owing to greater shoot vigour and (or) higher photosynthetic efficiency. Consequently, mature long-shoot early leaves possessed larger and thicker laminae, longer petioles, more side nerve pairs, and tended to grow more in length than width than short-shoot leaves on shoots of comparable age. Leaves of older short shoots, 2–10 years old, attained a greater size and had longer petioles than those of 1-year-old short shoots. Stem elongation and the development and expression of leaves in long shoots seemed to have a correlative influence on the overall vigour of long shoots.


Weed Science ◽  
1993 ◽  
Vol 41 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Albert J. Fischer ◽  
Eduardo Granados ◽  
Diego Trujillo

Dose-response studies estimating GR40 values indicated different levels of propanil resistance in junglerice populations from fields previously treated with propanil, compared to a check population collected where this herbicide had never been used. The GR40 for susceptible populations ranged from 0.36 to 0.50 kg ai ha−1and for resistant populations ranged from 1.10 to 3.10 kg ai ha−1. Considerable variability in growth and morphology existed among populations. Variability in cumulative leaf area, aboveground biomass, mean relative growth rate, mean net assimilation rate, and mean leaf area ratio could not be related to propanil resistance. Competitiveness was not related to propanil resistance either. of several vegetative and reproductive parameters measured at maturity, only grain weight per plant and number of grains per plant were correlated with GR40 (r = −0.73, P = 0.06). This trend towards lower reproductive fitness in propanil-resistant junglerice plants may reduce its ecological success when growing with propanil-susceptible plants in the absence of this herbicide.


1970 ◽  
Vol 48 (10) ◽  
pp. 1801-1804 ◽  
Author(s):  
D. F. W. Pollard

Different shoot types in aspen crowns carried leaves of different ages; leaders continued to produce leaves until early August and always carried some young leaves, whereas short shoots completed development by mid-June. Development of foliage on long shoots was intermediate between that on leaders and short shoots. Leaf area index of the 6-year-old stand reached a maximum of 2.4, of which 2.1 was contributed by short-shoot foliage. The rest was formed by leaders and long shoots. Young leaves on leaders and long shoots were not sufficient to influence total production in the stand appreciably, even though young aspen leaves may have high photosynthetic efficiencies. These young leaves could, however, influence height growth and lateral development of the canopy.


2001 ◽  
Vol 79 (11) ◽  
pp. 1270-1273 ◽  
Author(s):  
Pierre-Éric Lauri ◽  
Jean-Jacques Kelner

In a study of the apple (Malus ×domestica Borkh.) canopy structure, 5-year-old 'Fuji' and 'Braeburn' trees grafted on a low-vigour rootstock (M9) were compared at both fruiting branch and shoot levels. Percentages of short ([Formula: see text]5 cm) shoots and short shoot leaf area were significantly higher on 'Braeburn' than on 'Fuji', (76.8% vs. 72.6% and 46.9% vs. 42.9% for 'Braeburn' and 'Fuji', respectively). This high percentage of short shoots as compared with literature data was probably due to the training method, which reduced vigour. At shoot level, the ratio between dry masses of axis and leaf, called the axialization index, was determined to compare short and long shoots. Axialization values were higher for 'Braeburn' than for 'Fuji'. Although overall and individual leaf area was greater on long shoots, long shoot axialization (0.64 and 0.54 for 'Braeburn' and 'Fuji', respectively) was approximately twice that of short shoots (0.36 and 0.24, respectively). Therefore, for short shoots, the reduced carbon investment in supporting tissues may explain the significant role short shoots played in supporting early fruit development. For long shoots, the longer time required to reach the autotrophic and then exporting stage as well as the detrimental effect of early extension shoot development on fruit set might be explained by greater axialization.Key words: long shoot, short shoot, axialization index, apple, Malus ×domestica, biomass partitioning.


HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 266E-266
Author(s):  
Victor A. Kahn ◽  
C. Stevens ◽  
T. Mafolo ◽  
C. Bonsi ◽  
J.Y. Lu ◽  
...  

TU-82-155 and `Georgia-Jet' early maturing. `Carver II', TU-1892 and `Rojo-Blanco' late maturing sweetpotato, cultivars were evaluated in the field for 0.20 and 40% vine removal (VR) at 8 wk after transplanting. Parameters measured were: leaf area index (LAI) recovery, net assimilation rate, foliage crop growth rate (FCGR), storage roots crop growth rate (RCGR). alpha a (the mean relative growth rate in dry wt to the mean relative growth rate in leaf area over a time interval) or the partitioning of assimilates, total and marketable yield. A split. splitplot design was used and plants were sampled at 3 and 8 wk following VR. Except for TU-82-155 all cultivars showed significant LAI recovery above the control at 3 and 8 wk after vine removal when 20% of the vines were removed while at the 40% VR, only 'Georgia-Jet'. TU-1892 and 'Carver II' showed significant increases in LAI for the same periods. Net assimilation rate showed significant interactions while FCGR was not significantly affected by either 20 or 40 VR compared to the control at 3 or 8 wk after VR. RCGR was significantly affected by both levels of VR at 3 and 8 wk after VR and surplus assimilates (alpha a) showed significant interactions between cultivars and % VR. Told yield declined for all cultivars irrespective to maturity groups with the sharpest decrease being at the 20% VR. All cultivars except TU-82-155 showed a decrease in marketable yield, the increase in marketable yield of TU-82-155 was due to a lower non-marketable yield.


HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 267E-267
Author(s):  
Victor A Khan ◽  
C. Stevens ◽  
T. Mafolo ◽  
C. Bonsi ◽  
J.Y. Lu ◽  
...  

TU-82-155 and `Georgia-Jet' early maturing. `Carver II'. TU-1892 and `Rojo-Blanco' late maturing sweepotato cultivars were evaluated in the field for: leaf area index (LAI), net assimilation rate, foliage crop growth rate (FCGR), storage roots crop growth rate (RCGR) and alpha a (the mean relative growth rate in dry wt to the mean relative growth rate in leaf area over a time interval) or the partitioning of assimilates. A split plot design was used and plants were sampled at 6, 8, 11 and 16 wk after transplanting. The results from study showed that LAI reached maximum development 8 and 12 wk after transplanting for early and late maturing cultivars, respectively. All cultivars irrespective to maturity groups showed a reduction in net assimilation rate 6 wk after transplanting while FCGR for early maturing cultivars gradually declined 6 wk after transplanting and varied among late maturing cultivars. `Carver II' showed increases in FCGR up to 11 wk after transplanting then rapidly declined while `Rojo-Blanco' and TU-1892 began to decline 8 and 6 wk after transplanting, respectively. RCGR showed rapid increases (100 g.m /area/week) and (150 g/m /area/week) for early and late maturing cultivars beginning 6 wk after transplanting and this increase continued until the 12th and 8 th wk after transplanting for early and late maturing cultivars, respectively. Cultivars from both maturity groups began to produce surplus assimilates (Alpha a) 6 wk after transplanting. which coincided with the rapid increases in RCGR at the same time. Thus indicating that storage root enlargement begins after the plant had accumulated a surplus of assimilates.


1984 ◽  
Vol 62 (11) ◽  
pp. 2181-2192 ◽  
Author(s):  
W. R. Remphrey ◽  
G. R. Powell

Resting buds from five locations on long shoots in each of six crown positions were compared for 30 Larix laricina (Du Roi) K. Koch saplings. At each locus, bud sizes, numbers of bud scales and preformed leaf primordia (basal and axial for long-shoot buds), and apical widths were positively related to parent-shoot length. Along individual shoots, (i) terminal and lateral long-shoot buds contained fewer basal-leaf primordia than the more proximal short-shoot buds; (ii) terminal buds contained the most bud scales and axial-leaf primordia; and (iii) numbers of bud scales increased, while numbers of axial-leaf primordia generally decreased, basipetally among lateral buds. Comparison of bud leaf content with leaves on elongated shoots by regression showed that numbers of preformed and neoformed leaves increased with shoot length, but numbers of neoformed leaves did so to a greater degree. Internode lengths, numbers of leaves per lateral bud produced, and leaf lengths were greater on neoformed than on preformed shoot segments. Because of their capacity for neoformed growth following preformed growth and because of increases in internode lengths among all axial leaves, shoots from subjacent lateral buds replaced experimentally decapitated tree leaders (terminal buds) in one season, with little or no loss of height growth.


1983 ◽  
Vol 31 (6) ◽  
pp. 645 ◽  
Author(s):  
J Mowatt ◽  
PJ Myerscough

When four species of scribbly gums (Eucalyptus subseries Haemastominae) and four species of Angophora, together with Eucalyptus pilularis, were grown in a range of nutrient levels from distilled water to full Hoagland's nutrient solution, the two groups reacted differently, reflecting their contrasting distributions in relation to soil fertility. Their mean relative growth rates were similar, but the magnitude of the response to increasing nutrient availability varied among the angophoras although it was very similar for all the scribblies. The degree of response of the angophoras was correlated with the fertility of their natural soils: A. floribunda, coming from the most fertile soils, showed the greatest response in mean relative growth rate to increasing nutrient supply. Specific leaf areas did not vary among nutrient levels but, as with mean relative growth rates, the angophoras showed a correlation between the fertility of their natural soils and the specific leaf area: A. hispida, from the least fertile soils, developed the thickest leaves. The angophoras differed from each other in leaf area ratio whereas the scribblies did not. This characteristic was influenced by nutrient availability: the angophoras growing at the higher levels of nutrient supply developed greater leaf areas ratios. There was little difference among the four scribbly gum species in their response to nutrients. They all occur on infertile soils and showed little response to increased nutrient supply.


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