SHOOT GROWTH CHARACTERISTICS OF HETEROPHYLLOUS WOODY PLANTS

1966 ◽  
Vol 44 (6) ◽  
pp. 827-843 ◽  
Author(s):  
T. T. Kozlowski ◽  
J. Johanna Clausen

Observations were made on relationships between contents of winter buds and subsequent shoot growth characteristics of Betula papyrifera, B. alleghaniensis, Populus tremuloides, and P. grandidentata. In both species of Betula, winter buds expected to produce long shoots contained both embryonic leaves and leaf primordia. Both early and late leaves were produced by growing shoots. In contrast, in both species of Populus all leaves produced on the observed shoots appeared at bud break and matured rapidly. Evidence for a variety of patterns and degrees of dependency of expanding shoot systems on reserve foods and currently produced carbohydrates is presented. Shoot elongation of species with shoots fully preformed in the winter bud utilizes large amounts of reserve carbohydrates. In growth of long shoots of heterophyllous species considerable current photosynthate appears to be used. In Betula the contribution of early and late leaves to shoot growth differed markedly. Covering of early leaves before mid-June inhibited shoot growth. The presence of normally growing early leaves was essential for normal shoot development and survival.

1992 ◽  
Vol 10 (2) ◽  
pp. 101-103
Author(s):  
Guochen Yang ◽  
Paul E. Read

Abstract Experiments were conducted to evaluate the feasibility of pre-forcing treatments for the release of bud dormancy of dormant stems of lilac, privet and Vanhoutte spirea. The new softwood growth of these dormant stems was used either as explants for in vitro culture or as cuttings for rooting studies of woody plant species in the off-season. A pre-forcing 15% bleach solution (0.78% NaOCl) soak hastened bud break, enhanced percentage of bud break, and promoted shoot elongation. Pre-forcing wetting agent treatments produced similar results to those of the bleach soak with variation among wetting agents and plant species. Smaller treatment differences were observed in the forcing characteristics when stems were collected later in the winter, probably because the cold requirement of the buds had been completely or partially met. This technique will provide explants for in vitro culture and softwood cuttings for propagation of woody plants over an extended period.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Reza Azadi Gonbad ◽  
Uma Rani Sinniah ◽  
Maheran Abdul Aziz ◽  
Rosfarizan Mohamad

The use ofin vitroculture has been accepted as an efficient technique for clonal propagation of many woody plants. In the present research, we report the results of a number of experiments aimed at optimizing micropropagation protocol for tea (Camellia sinensis(L.) O. Kuntze) (clone Iran 100) using nodal segments as the explant. The effect of different combinations and concentrations of plant growth regulators (PGR) (BAP, TDZ, GA3) on shoot multiplication and elongation was assessed. The influence of exposure to IBA in liquid form prior to transfer to solid media on rooting of tea microshoots was investigated. The results of this study showed that the best treatment for nodal segment multiplication in terms of the number of shoot per explant and shoot elongation was obtained using 3 mg/L BAP in combination with 0.5 mg/L GA3. TDZ was found to be inappropriate for multiplication of tea clone Iran 100 as it resulted in hyperhydricity especially at concentrations higher than 0.05 mg/L. Healthy shoots treated with 300 mg/L IBA for 30 min followed by transfer to 1/2 strength MS medium devoid of PGR resulted in 72.3% of shoots producing roots and upon transferring them to acclimatization chamber 65% survival was obtained prior to field transfer.


1967 ◽  
Vol 45 (9) ◽  
pp. 1643-1651 ◽  
Author(s):  
J. Johanna Clausen ◽  
T. T. Kozlowski

Tamarack (Larix laricina (DuRoi) K. Koch) produces long shoots which bear two kinds of needles. Early needles are present in the bud and elongate rapidly after budbreak. Late needles, few of which are present in the bud, elongate later than early needles. Short shoots bear early needles only, and stem length seldom exceeds 1 mm. Seasonal changes in length and weight of needles and stems of both shoot types were measured. In long shoots, 75% of stem elongation, more than 70% of stem weight increment, and 65–70% of late needle elongation occurred after early needles were full-sized. Stem and late needle elongation ceased simultaneously, after which time needle weight decreased and stem weight increased. Early needles probably drew on food reserves while developing, and then themselves contributed to stem and late needle elongation. Final stem weight increase probably used photosynthate from both late and early needles of the current year.Shading of current and last year's needles showed that shoots in which photosynthesis was interrupted in this way produced shorter, lighter-weight stems than did control shoots.


2008 ◽  
Vol 62 (3) ◽  
pp. 357-363 ◽  
Author(s):  
Huang Yi ◽  
Mónica Calvo Polanco ◽  
Michael D. MacKinnon ◽  
Janusz J. Zwiazek

2013 ◽  
Vol 36 (1-2) ◽  
pp. 83-94 ◽  
Author(s):  
Franciszka Jaumień

The growth of trees sprayed in spring with chlormequat is weaker, and their elongation growth ends 2 - 3 weeks earlier than that of unsprayed trees. Trees with growth inhibited by chlormequat set flower buds on the spurs and in the subapical part of long shoots. The course of flower bud differentiation starts in the second half of July and is similar to that in the apple tree.


2017 ◽  
Author(s):  
Daniel Conde ◽  
Mariano Perales ◽  
Anne-Laure Le Gac ◽  
Christopher Dervinis ◽  
Matias Kirst ◽  
...  

AbstractAnnual dormancy-growth cycle is a developmental and physiological process essential for the survival of temperate and boreal forests. Seasonal control of shoot growth in woody perennials requires specific genetic programs integrated with the environmental signals. The environmental-controlled mechanisms that regulate the shift between winter dormancy to growth promoting genetic program are still unknown. Here, we show that dynamics in genomic DNA methylation (gDNA) levels regulate dormancy-growth cycle in poplar. We proved that the reactivation of cell division in the apical shoot that lead bud break process in spring, is preceded by a progressive reduction of gDNA methylation in apex tissue. We also identified that the induction in apex tissue of a chilling-dependent poplar DEMETER-LIKE 10 (PtaDML10) DNA demethylase precedes shoot growth reactivation. Transgenic poplars showing down-regulation of PtaDML8/10 caused delayed bud break. Genome wide transcriptome and methylome analysis and data mining revealed the gene targets of active DML-dependent DNA demethylation genetically associated to bud break. These data point to a chilling dependent-DEMETER-like DNA demethylase controlling the genetic shift from winter dormancy to a condition that promotes shoot apical vegetative growth in poplar.


2013 ◽  
Vol 50 (3) ◽  
pp. 398-406 ◽  
Author(s):  
MOHAMED GHRAB ◽  
MEHDI BEN MIMOUN

SUMMARYClimate change characterized by global warming is expected to have an incidence on fruit trees’ development and production. The severity of these effects depends on lack of chilling. The current study focused on the research of an optimal dose of hydrogen cyanamide (Dormex®) treatment which can advance the bud break of female pistachio trees (Pistacia veraL.) to ensure better blooming synchronization with pollinators. A field experiment was conducted in northern Tunisia (36°49′N, 9°48′E) on mature pistachio trees. Two hydrogen cyanamide treatments at 2% and 4% Dormex® were applied with reference to the control untreated trees. The flowering time, vegetative growth, starch content, productivity and nut characters were followed. Results show that 4% Dormex® advanced the normal bud break by 15 days and flowering by 11 days and improved natural pollination by synchronization of male and female flowers. Consequently, fresh yield and nut quality as split and blank rates and nut weight were improved. However, shoot growth, leaf area and starch content in current shoot seemed unaffected by hydrogen cyanamide applications. In conclusion, hydrogen cyanamide could be used as 4% Dormex® and sprayed 45 days before bud break to improve pistachio productivity and prevent anomalies of lack of chilling due to global warming that could be more frequent in the Mediterranean areas.


1998 ◽  
Vol 38 (8) ◽  
pp. 879 ◽  
Author(s):  
C. A. Offord ◽  
S. Muir ◽  
J. L. Tyler

Summary. In 2 experiments coir fibre (coconut mesocarp) was compared with peat as a propagation or potting mix component for selected Australian native plants. The first experiment investigated root and shoot growth on cuttings of Pultenaea parviflora grown in mixes of peat : perlite : sand 4:7:3, coir : perlite : sand 4:7:3 or coir:perlite:sand 3:7:3. No differences in rooting or shoot regrowth were detected even though there were some differences in the chemical and physical characteristics of the mixes. Over 2 months, pH of the coir mixes rose from 3.3 and 3.9 to 5.8 and 5.6, respectively, whilst electrical conductivity decreased from 0.253 and 0.127 dS/m to 0.095 and 0.103 dS/m. The physical characteristics (air-filled porosity and water-holding capacity) of the mixes did not change substantially over time. In the second experiment, Brachyscome multifida var. dilatata, Correa ‘Dusky Bells’, Eucalyptus melliodora and Grevillea × gaudichaudii were potted into peat : sand 1:2, coir:sand 1:2 or coir:sand 1:3; whilst Callicoma serratifolia and Lomandra longifolia were potted into peat:sand 1:2, coir:sand 1:2 or coir:sand 1:5. All taxa and potting mix combinations were subjected to a ‘less frequent’ or ‘more frequent’ watering regime. The physical and chemical characteristics of the mixes were all within the Australian standard recommendations (AS 3743-1996) with the exception of pH which was initially slightly higher than recommended in all mixes. Analysis of growth characteristics over 14 months did not reveal any clear overall differences between mixes, indicating that coir was comparable with peat.


2019 ◽  
Vol 60 (12) ◽  
pp. 2797-2811 ◽  
Author(s):  
Niveditha Umesh Katyayini ◽  
P�ivi L H Rinne ◽  
Christiaan van der Schoot

Abstract The biosynthesis and roles of strigolactones (SLs) have been investigated in herbaceous plants, but so far, their role in trees has received little attention. In this study, we analyzed the presence, spatial/temporal expression and role of SL pathway genes in Populus tremula � Populus tremuloides. In this proleptic species, axillary buds (AXBs) become para-dormant at the bud maturation point, providing an unambiguous starting point to study AXB activation. We identified previously undescribed Populus homologs of DWARF27 (D27), LATERAL BRANCHING OXIDOREDUCTASE (LBO) and DWARF53-like (D53-like) and analyzed the relative expression of all SL pathway genes in root tips and shoot tissues. We found that, although AXBs expressed MORE AXILLARY GROWTH1 (MAX1) and LBO, they did not express MAX3 and MAX4, whereas nodal bark expressed high levels of all SL biosynthesis genes. By contrast, expression of the SL perception and signaling genes MAX2, D14 and D53 was high in AXBs relative to nodal bark and roots. This suggests that AXBs are reliant on the associated nodes for the import of SLs and SL precursors. Activation of AXBs was initiated by decapitation and single-node isolation. This rapidly downregulated SL pathway genes downstream of MAX4, although later these genes were upregulated coincidently with primordia formation. GR24-feeding counteracted all activation-related changes in SL gene expression but did not prevent AXB outgrowth showing that SL is ineffective once AXBs are activated. The results indicate that nodes rather than roots supply SLs and its precursors to AXBs, and that SLs may restrain embryonic shoot elongation during AXB formation and para-dormancy in intact plants.


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