Development of white spruce (Picea glauca) seedling roots

1985 ◽  
Vol 63 (3) ◽  
pp. 456-462 ◽  
Author(s):  
Anne M. Johnson-Flanagan ◽  
John N. Owens
Keyword(s):  
Root System ◽  
Picea Glauca ◽  
Lateral Roots ◽  
Root Apex ◽  
White Spruce ◽  
Growth Cycle ◽  
Root Tip ◽  
System A ◽  
Seedling Roots ◽  
Specific Phase

The root system of container-grown white spruce seedlings (Picea glauca (Moench) Voss) consists of a taproot and many lateral roots. The lateral roots can be divided into three classes on the basis of external morphology. Although growth cycles of individual roots are independent, there are overall trends of growth in the root system. A preponderance of one morphological root class is usually associated with a specific phase of the growth cycle. Apical organization in absorbing and elongating roots is similar. When elongation ceases, roots become brown as a result of two separate processes, suberization of the endodermis and metacutization of a discrete layer enveloping the root apex. Zonation in the apex is reduced in brown roots. Renewed growth is marked by swelling of the brown root apex followed by the emergence of a white root tip.

scholarly journals Modelling time variations of root diameter and elongation rate as related to assimilate supply and demand

2020 ◽  
Vol 71 (12) ◽  
pp. 3524-3534
Author(s):  
Loïc Pagès ◽  
Marie Bernert ◽  
Guillaume Pagès
Keyword(s):  
Root System ◽  
Root Elongation ◽  
Lateral Roots ◽  
Supply And Demand ◽  
Root System Architecture ◽  
Elongation Rate ◽  
Growth Patterns ◽  
Root Tip ◽  
Generic Model ◽  
Maximal Diameter

Abstract In a given root system, individual roots usually exhibit a rather homogeneous tip structure although highly different diameters and growth patterns, and this diversity is of prime importance in the definition of the whole root system architecture and foraging characteristics. In order to represent and predict this diversity, we built a simple and generic model at root tip level combining structural and functional knowledge on root elongation. The tip diameter, reflecting meristem size, is used as a driving variable of elongation. It varies, in response to the fluctuations of photo-assimilate availability, between two limits (minimal and maximal diameter). The elongation rate is assumed to be dependent on the transient value of the diameter. Elongation stops when the tip reaches the minimal diameter. The model could satisfactorily reproduce patterns of root elongation and tip diameter changes observed in various species at different scales. Although continuous, the model could generate divergent root classes as classically observed within populations of lateral roots. This model should help interpret the large plasticity of root elongation patterns which can be obtained in response to different combinations of endogenous and exogenous factors. The parameters could be used in phenotyping the root system.

The utility of the two-pass harvesting system: an analysis using the ecosystem simulation model FORECAST

2002 ◽  
Vol 32 (6) ◽  
pp. 1071-1079 ◽  
Author(s):  
Clive Welham ◽  
Brad Seely ◽  
Hamish Kimmins
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Ecosystem Model ◽  
Yield Potential ◽  
Model Forecast ◽  
Pass System ◽  
System A ◽  
Ecosystem Simulation ◽  
Harvesting Systems

The ecosystem model FORECAST was used to simulate the yield potential in Saskatchewan mixedwoods of the two-pass harvesting system. The simulated two-pass stand consisted of an overstory population of pure trembling aspen (Populus tremuloides Michx.) with a white spruce (Picea glauca (Moench) Voss) understory. The aspen was removed at year 60, and yields of the understory spruce and resprouting aspen were simulated for 80 years thereafter. The two-pass simulations were compared with two simulated conventional harvesting systems. The first system consisted of a single final harvest at year 140. In the second system, a clearcut was conducted at year 60. White spruce was then planted in the subsequent year at 400, 600, or 800 stems/ha, and aspen also permitted to resprout. Growth was then simulated for a further 80 years. FORECAST projections indicated that the two-pass system might be effective for releasing the white spruce understory, achieving at least a twofold gain in spruce volume relative to conventional methods. Furthermore, total volumes exceeded those derived from the unmanaged stand, while second rotation yields of aspen declined with spruce understory density. These simulations suggest the two-pass harvesting system has strong potential as a tool for mixedwood management.

scholarly journals Root System Characteristics of Young Papaya Plants

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 604b-604 ◽  
Author(s):  
Thomas E. Marler ◽  
Haluk M. Discekici
Keyword(s):  
Root System ◽  
Root Length ◽  
Fruit Set ◽  
Lateral Roots ◽  
Dry Mass ◽  
Total Root Length ◽  
System A ◽  
Radial Spread ◽  
System Characteristics ◽  
Proportional Distribution

Excavation of field-grown `Red Lady' and `Tainung #2' papaya plants was begun 3 months after transplanting to the field to characterize development of the papaya root system. The roots were separated into the taproot system and lateral roots within three size categories: <1, 1 to 5, and >5 mm. Length of the taproot system and the larger lateral roots was measured directly, and that of the smaller roots was determined using the line-intersect method. Mass of the various size categories was measured after drying at 70°C. A typical plant 3 months after field-planting was ≈ 60 cm tall and exhibited a root system radial spread of 34,636 cm2, total root length of 9613 cm, and total dry mass of 17.3 g. The taproot system accounted for >70% of the mass and <5% of the length of the root system. Lateral roots <1 mm in diameter accounted for <10% of the mass and >70% of the length of the root system. A typical plant during the heavy fruit set stage, about 6 months after field planting, was 175 cm tall and exhibited a root system radial spread of 101,736 cm2, total root length of 975 m, and total dry mass of 539 g. The taproot system accounted for ≈38% of the dry mass and <1% of the length of the root system. Lateral roots <1 mm in diameter accounted for ≈5% of the dry mass and 65% of the length of the root system. Plant age influenced root system characteristics more than cultivar, especially the proportional distribution of mass and length among the defined root classes.

Effects of partial cutting on the ectomycorrhizae of Picea glauca forests in northwestern Alberta

2005 ◽  
Vol 35 (6) ◽  
pp. 1442-1454 ◽  
Author(s):  
Lance W Lazaruk ◽  
Gavin Kernaghan ◽  
S Ellen Macdonald ◽  
Damase Khasa
Keyword(s):  
Picea Glauca ◽  
Effective Means ◽  
White Spruce ◽  
Root Tip ◽  
Root Tips ◽  
Partial Cutting ◽  
Disturbance Intensity ◽  
Tree Retention ◽  
Green Tree Retention ◽  
The Impact

This study assessed the impact of various harvesting practices (including those designed to emulate natural disturbances) on ectomycorrhizae (ECM) associated with white spruce (Picea glauca (Moench) Voss) in northwestern Alberta, Canada. Treatments included clearcuts, partial cuts (dispersed green-tree retention with 20%, 50%, and 75% residual live trees, and aggregated green-tree retention), unharvested control sites, and a burned stand. The percentage of active white spruce root tips and ECM richness and diversity, as observed in soil cores collected throughout the study site, all decreased with increasing disturbance intensity. Effects were particularly pronounced in clearcuts, machine corridors used for access by harvesting equipment in the dispersed green-tree retention stands, and in burned areas. Reductions in ECM biodiversity could be attributed to the sensitivity of late-stage ectomycorrhizae (e.g., Cortinarius spp., Lactarius spp., and Russula spp.) to soil disturbances and changes in microclimate associated with harvesting or burning. Areas of dispersed and aggregated green-tree retention were not dramatically different than unharvested forest in terms of root tip density and ECM richness, diversity, and composition. Harvesting practices that retain a percentage of residual live trees, either dispersed throughout the cutting unit or in aggregated patches, could be an effective means of maintaining ectomycorrhizal biodiversity at the stand level.

scholarly journals WUSCHEL-related homeobox family genes in rice control lateral root primordium size

2022 ◽  
Vol 119 (1) ◽  
pp. e2101846119
Author(s):  
Tsubasa Kawai ◽  
Kyosuke Shibata ◽  
Ryosuke Akahoshi ◽  
Shunsaku Nishiuchi ◽  
Hirokazu Takahashi ◽  
...  
Keyword(s):  
Root System ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Lateral Roots ◽  
Root Tip ◽  
Early Developmental Stage ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Causative Gene ◽  
Variable Environments

The development of a plastic root system is essential for stable crop production under variable environments. Rice plants have two types of lateral roots (LRs): S-type (short and thin) and L-type (long, thick, and capable of further branching). LR types are determined at the primordium stage, with a larger primordium size in L-types than S-types. Despite the importance of LR types for rice adaptability to variable water conditions, molecular mechanisms underlying the primordium size control of LRs are unknown. Here, we show that two WUSCHEL-related homeobox (WOX) genes have opposing roles in controlling LR primordium (LRP) size in rice. Root tip excision on seminal roots induced L-type LR formation with wider primordia formed from an early developmental stage. QHB/OsWOX5 was isolated as a causative gene of a mutant that is defective in S-type LR formation but produces more L-type LRs than wild-type (WT) plants following root tip excision. A transcriptome analysis revealed that OsWOX10 is highly up-regulated in L-type LRPs. OsWOX10 overexpression in LRPs increased the LR diameter in an expression-dependent manner. Conversely, the mutation in OsWOX10 decreased the L-type LR diameter under mild drought conditions. The qhb mutants had higher OsWOX10 expression than WT after root tip excision. A yeast one-hybrid assay revealed that the transcriptional repressive activity of QHB was lost in qhb mutants. An electrophoresis mobility shift assay revealed that OsWOX10 is a potential target of QHB. These data suggest that QHB represses LR diameter increase, repressing OsWOX10. Our findings could help improve root system plasticity under variable environments.

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