Understanding the shoot sink.

2022 ◽  
pp. 35-53
Author(s):  
T. M. DeJong

Abstract To more fully understand how all the major organs of a tree interact in the semi-autonomous scheme of assimilate distribution and tree functioning, it is important to understand their development and growth behavior. This chapter presents a general description of the development and growth characteristics of the major organs (shoot and leaf) of fruit trees, including shoot structure, morphology and orientation; diurnal patterns of shoot growth; seasonal growth patterns of shoot growth and dormancy; as well as tree aging.

2019 ◽  
Vol 116 (22) ◽  
pp. 10852-10857 ◽  
Author(s):  
Pál Miskolczi ◽  
Rajesh Kumar Singh ◽  
Szymon Tylewicz ◽  
Abdul Azeez ◽  
Jay P. Maurya ◽  
...  

In perennial plants, seasonal shifts provide cues that control adaptive growth patterns of the shoot apex. However, where these seasonal cues are sensed and communicated to the shoot apex remains unknown. We demonstrate that systemic signals from leaves play key roles in seasonal control of shoot growth in model tree hybrid aspen. Grafting experiments reveal that the tree ortholog of Arabidopsis flowering time regulator FLOWERING LOCUS T (FT) and the plant hormone gibberellic acid (GA) systemically convey seasonal cues to the shoot apex. GA (unlike FT) also acts locally in shoot apex, downstream of FT in seasonal growth control. At the shoot apex, antagonistic factors—LAP1, a target of FT and the FT antagonist TERMINAL FLOWER 1 (TFL1)—act locally to promote and suppress seasonal growth, respectively. These data reveal seasonal changes perceived in leaves that are communicated to the shoot apex by systemic signals that, in concert with locally acting components, control adaptive growth patterns.


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.


1982 ◽  
Vol 60 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Fred L. Bunnell

Data on lambing periods from 30 populations of North American mountain sheep are reviewed. Among all populations lambing begins later and duration is shorter at more northern altitudes (p < 0.00006). Correlations are enhanced (p < 0.00003) when latitude is replaced by a phenological index incorporating altitude. Termination of lambing is not correlated with latitude or with phenological index. Two broad patterns are evident. Populations feeding on vegetation of less predictable growth patterns ("desert type") have lengthy lambing seasons; populations feeding on vegetation exhibiting more predictable growth patterns ("alpine type") have shorter lambing seasons, typically two oestrous cycles in length. Definition of "types" by latitude or sheep taxonomy reveals significant differences in lambing periods, but correlations are enhanced when "types" are defined on the basis of habitat.Among taxa, birth weights are correlated with female body weight (rs = 0.87). Birth weights are heavier in extreme environments, seasonal growth patterns are expressed better in the alpine type, and early weight gain is most rapid in the northernmost subspecies. All populations show a strong central tendency with regard to peak lambing (17 May ± 6.8 days). Departures from that tendency respond more to predictability of vegetation than to thermal stress or predation pressure.


2017 ◽  
Vol 100 (10) ◽  
pp. 1315-1327 ◽  
Author(s):  
Anthony R. Vastano ◽  
Kenneth W. Able ◽  
Olaf P. Jensen ◽  
Paola C. López-Duarte ◽  
Charles W. Martin ◽  
...  

1995 ◽  
Vol 120 (2) ◽  
pp. 211-216 ◽  
Author(s):  
J. Roger Harris ◽  
Nina L. Bassuk ◽  
Richard W. Zobel ◽  
Thomas H. Whitlow

The objectives of this study were to determine root and shoot growth periodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees and to evaluate three methods of root growth periodicity measurement. Two methods were evaluated using a rhizotron. One method measured the extension rate (RE) ofindividual roots, and the second method measured change in root length (RL) against an observation grid. A third method, using periodic counts of new roots present on minirhizotrons (MR), was also evaluated. RE showed the least variability among individual trees. Shoot growth began before or simultaneously with the beginning of root growth for all species with all root growth measurement methods. All species had concurrent shoot and root growth, and no distinct alternating growth patterns were evident when root growth was measured by RE. Alternating root and shoot growth was evident, however, when root growth was measured by RL and MR. RE measured extension rate of larger diameter lateral roots, RL measured increase in root length of all diameter lateral roots and MR measured new root count of all sizes of lateral and vertical roots. Root growth periodicity patterns differed with the measurement method and the types of roots measured.


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.


2017 ◽  
Vol 37 (1) ◽  
pp. 60-60 ◽  
Author(s):  
Dominik Florian Stangler ◽  
Andreas Hamann ◽  
Hans-Peter Kahle ◽  
Heinrich Spiecker

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.


2000 ◽  
Vol 40 (1) ◽  
pp. 37 ◽  
Author(s):  
S. J. Lolicato

Fortnightly soil water content measurements to a depth of 2.1 m under 4 cocksfoot cultivars, 2 phalaris cultivars, 2 lucerne cultivars and 1 Lotus corniculatus cultivar were used to compare soil profile drying and to define seasonal patterns of plant water use of the species over a 3-year period, on a duplex soil. Cultivars were also selected, within species groups, for varying seasonal growth patterns to assess this influence on soil water dynamics and growth. Over the 3-year period, treatments with the highest and lowest measures of profile soil water content were used to derive and compare values of maximum plant extractable water. Plots were maintained for a further 3 years, after which soil water content measurements in autumn were used to assess long-term effects of the treatments. The effect of seasonal growth patterns within a species was negligible; however, there were significant differences between species. Twenty-one months after pasture establishment, lucerne alone had a drying effect at 2.0 m depth and subsequently it consistently showed profiles with the lowest soil water content. Maximum plant extractable water was greatest for lucerne (230 mm), followed by phalaris (210 mm), Lotus corniculatus (200 mm) and cocksfoot (170 mm). Profiles with the lowest soil water content were associated with greater herbage growth and greater depths of water extraction. The soil water deficits developed by the treatments in autumn of the fourth year were similar to those measured in autumn of the seventh year, implying that a species-dependant equilibrium had been reached. Long-term rainfall data is used to calculate the probabilities of recharge occurring when rainfall exceeds maximum potential deficits for the different pasture species.


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