Root development under fluctuating soil physical stress – plastic and elastic responses

2020 ◽  
Author(s):  
Tino Colombi ◽  
Hanna Sjulgård ◽  
Daniel Iseskog ◽  
Thomas Keller
Keyword(s):  
Growth Rate ◽  
Root Growth ◽  
Root Development ◽  
Optimal Growth ◽  
Penetration Resistance ◽  
Growth Conditions ◽  
Physical Stress ◽  
Soil Air ◽  
Physical Conditions ◽  
Root Growth Rate

<p>Physical properties of soil such as penetration resistance and oxygen concentration of soil air strongly influence root system development in plants. Soils typically exhibit considerable spatial and temporal fluctuations in penetration resistance and oxygen concentration of soil air due to wetting-drying cycles, small-scale differences in soil compactness or hotspots of biological activity. Hence, roots of a single plant are exposed to different physical environments and thus physical stresses during their growth through the soil profile. Plants are known to adjust their root development to these spatiotemporal fluctuations in soil physical conditions. Such phenotypic adjustments include changes of root growth rate as well as alterations of root morphology and anatomy. However, these adjustments reduce accessibility of water and nutrients and may increase the carbon demand for soil exploration, which limits aboveground plant development. Until now, it is unclear whether such adjustments in root development are plastic (i.e. the phenotype is irreversibly changed even when roots re-enter zones with optimal growth conditions) or elastic (i.e. the phenotype is only temporarily changed and recovers again when roots re-enter zones with optimal growth conditions).</p><p>To investigate the plasticity and elasticity of root development, we designed customized microrhizotrons in which soil penetration resistance and the concentration of oxygen in soil air can be varied. Near-infrared (λ=830 nm) time-lapse imaging was applied to quantify root growth rates, and combined with measurements of root morphology and anatomy. A series of experiments was conducted using different crop species with contrasting root system properties (fibrous vs. taproot system, thin vs. thick roots). After an establishment period of three days under optimal growth conditions, roots were exposed for 24 hours to increased penetration resistance, hypoxia and the combination of both stresses. Following this, the stress was released, and plants continued to grow for 24 hours at optimal conditions, before a second stress was applied for another 24 hours. Generally, root development responded to changes in soil physical conditions across all species. However, depending on the species, the adjustments in root development were found to be constant or temporary, i.e. plastic or elastic. This difference between species was particularly pronounced for root growth rate. Root growth rate in pea recovered after soil physical stress was released, while root growth rate in wheat remained low after stress release. The obtained findings will be discussed with respect to the tolerance of different plants to soil physical stress as well as the effects of root growth on soil structure dynamics.</p>

scholarly journals Response of Bromus valdivianus (Pasture Brome) Growth and Physiology to Defoliation Frequency Based on Leaf Stage Development

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2058
Author(s):  
Iván P. Ordóñez ◽  
Ignacio F. López ◽  
Peter D. Kemp ◽  
Daniel J. Donaghy ◽  
Yongmei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stomatal Conductance ◽  
Root Growth ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Leaf Stage ◽  
Water Soluble Carbohydrates ◽  
Stage Development ◽  
Defoliation Frequency ◽  
Root Growth Rate

The increase in drought events due to climate change have enhanced the relevance of species with greater tolerance or avoidance traits to water restriction periods, such as Bromus valdivianus Phil. (B. valdivianus). In southern Chile, B. valdivianus and Lolium perenne L. (L. perenne) coexist; however, the pasture defoliation criterion is based on the physiological growth and development of L. perenne. It is hypothesised that B. valdivianus needs a lower defoliation frequency than L. perenne to enhance its regrowth and energy reserves. Defoliation frequencies tested were based on B. valdivianus leaf stage 2 (LS-2), leaf stage 3 (LS-3), leaf stage 4 (LS-4) and leaf stage 5 (LS-5). The leaf stage development of Lolium perenne was monitored and contrasted with that of B. valdivianus. The study was conducted in a glasshouse and used a randomised complete block design. For Bromus valdivianus, the lamina length, photosynthetic rate, stomatal conductance, tiller number per plant, leaf area, leaf weights, root growth rate, water-soluble carbohydrates (WSCs) and starch were evaluated. Bromus valdivianus maintained six live leaves with three leaves growing simultaneously. When an individual tiller started developing its seventh leaf, senescence began for the second leaf (the first relevant leaf for photosynthesis). Plant herbage mass, the root growth rate and tiller growth were maximised at LS-4 onwards. The highest leaf elongation rate, evaluated through the slope of the lamina elongation curve of a fully expanded leaf, was verified at LS-4. The water-soluble carbohydrates (WSCs) increased at LS-5; however, no statistical differences were found in LS-4. The LS-3 and LS-2 treatments showed a detrimental effect on WSCs and regrowth. The leaf photosynthetic rate and stomatal conductance diminished while the leaf age increased. In conclusion, B. valdivianus is a ‘six-leaf’ species with leaf senescence beginning at LS-4.25. Defoliation at LS-4 and LS-5 was optimum for plant regrowth, maximising the aboveground plant parameters and total WSC accumulation. The LS-4 for B. valdivianus was equivalent to LS-3.5 for L. perenne. No differences related to tiller population in B. valdivianus were found in the different defoliation frequencies.

scholarly journals Root Morphology of Eight Hybrid Oil Palms Under Iron (Fe) Toxicity

2016 ◽  
Vol 1 (1) ◽  
pp. 013
Author(s):  
Aprilia Ike Nurmalasari ◽  
Eka Tarwaca Susila Putra ◽  
Prapto Yudono
Keyword(s):  
Growth Rate ◽  
Root Growth ◽  
Surface Area ◽  
Root Morphology ◽  
Block Design ◽  
Dry Weight ◽  
Root Volume ◽  
Oil Palms ◽  
Fe Toxicity ◽  
Root Growth Rate

The research aims to study the change of morphology root characters of eight hybrid oil palms under iron toxicity (Fe). Field experiment done in arranged in a Randomized Complete Block Design (RCBD) two factors and three blocks as replications. The first factor was Fe concentration. It consists of two levels which are concentration 0µ.g-1 and concentration 600 µg.g-1 Fe. The second factor is the hybrid of oil palms which consists of eight hybrid oil palms as Yangambi, Avros, Langkat, PPKS 239, Simalungun, PPKS 718, PPKS 540 and Dumpy. Fe was applied by pouring FeSO4 solvent for 600 µg.g-1 500 ml.-1plant.-1day-1 on two months of plants after transplanting in the main nursery. Data were collected on root morphology and plant dry weight The data were analysis of variance (ANOVA) at 5% significanly, followed by Duncan's multiple range test (DMRT). The relationships by among variables were determined by correlation analysis. The results showed that Fe concentration 600 µg.g-1 inhibits relatively root growth rate, narrows surface area, reduces the diameter, and shrinks root volume of all hybrid oil palms tested. The slowing relatively root growth rate, narrowing of root surface area and root diameter also root volume shrinkage due to Fe stress. It was also shown that the dry weight of plants was inhibit by existing of Fe toxicity.

scholarly journals <sup>210</sup>Pb-<sup>226</sup>Ra chronology reveals rapid growth rate of <i>Madrepora oculata</I> and <i>Lophelia pertusa</i> on world's largest cold-water coral reef

2011 ◽  
Vol 8 (6) ◽  
pp. 12247-12283
Author(s):  
P. Sabatier ◽  
J.-L. Reyss ◽  
J. M. Hall-Spencer ◽  
C. Colin ◽  
N. Frank ◽  
...  
Keyword(s):  
Growth Rate ◽  
Coral Reef ◽  
Linear Growth ◽  
Cold Water ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Age And Growth ◽  
Linear Growth Rate ◽  
Lophelia Pertusa ◽  
Water Coral

Abstract. Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of corals from one of the world's largest known cold-water coral reef, the Røst Reef off Norway. Two large branching framework-forming cold-water coral specimens, one Lophelia pertusa and one Madrepora oculata were collected alive at 350 m water depth from the Røst Reef at ~67° N and ~9° E. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and the corals trace element compositions were studied using ICP-QMS. Due to the different chemical behaviors of Pb and Ra in the marine environment, 210Pb and 226Ra were not incorporated the same way into the aragonite skeleton of those two cold-water corals. Thus to assess of the growth rates of both specimens we have here taken in consideration the exponential decrease of initially incorporated 210Pb as well as the ingrowth of 210Pb from the decay of 226Ra. Moreover a~post-depositional 210Pb incorporation is found in relation to the Mn-Fe coatings that could not be entirely removed from the oldest parts of the skeletons. The 226Ra activities in both corals were fairly constant, then assuming constant uptake of 210Pb through time the 210Pb-226Ra chronology can be applied to calculate linear growth rate. The 45.5 cm long branch of M. oculata reveals an age of 31 yr and a~linear growth rate of 14.4 ± 1.1 mm yr−1, i.e. 2.6 polyps per year. However, a correction regarding a remaining post-depositional Mn-Fe oxide coating is needed for the base of the specimen. The corrected age tend to confirm the radiocarbon derived basal age of 40 yr (using 14C bomb peak) with a mean growth rate of 2 polyps yr−1. This rate is similar to the one obtained in Aquaria experiments under optimal growth conditions. For the 80 cm-long specimen of L. pertusa a remaining contamination of metal-oxides is observed for the middle and basal part of the coral skeleton, inhibiting similar accurate age and growth rate estimates. However, the youngest branch was free of Mn enrichment and this 15 cm section reveals a growth rate of 8 mm yr−1 (~1 polyp every two to three years). However, the 210Pb growth rate estimate is within the lowermost ranges of previous growth rate estimates and may thus reflect that the coral was not developing at optimal growth conditions. Overall, 210Pb-226Ra dating can be successfully applied to determine the age and growth rate of framework-forming cold-water corals, however, removal of post-depositional Mn-Fe oxide deposits is a prerequisite. If successful, large branching M. oculata and L. pertusa coral skeletons provide unique oceanographic archive for studies of intermediate water environmentals with an up to annual time resolution and spanning over many decades.

Statistical analysis of root growth rate determinations

1980 ◽  
Vol 20 (4) ◽  
pp. 389-396 ◽  
Author(s):  
Christopher Cox ◽  
Henry T. Davis ◽  
Morton W. Miller ◽  
Dominique Robertson
Keyword(s):  
Growth Rate ◽  
Statistical Analysis ◽  
Root Growth ◽  
Root Growth Rate

Components of the Variability of Radial Cell Size in Tree Rings of Conifers

IAWA Journal ◽  
1989 ◽  
Vol 10 (4) ◽  
pp. 417-426 ◽  
Author(s):  
L.G. Vysotskaya ◽  
E.A. Vaganov
Keyword(s):  
Growth Rate ◽  
Soil Moisture ◽  
Cell Size ◽  
Climatic Factors ◽  
Size Variation ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Radial Cell ◽  
Natural Stands ◽  
Main Components

Radial cell size of conifers of three speeies: Pinus sylvestris, Larix sibirica, and Larix gmelinii from natural stands in the south of the Krasnoyarsk region (USSR) have been measured with a semi-automated device. The main factors responsible for cell size variation have been determined. These are: age, growth rate, soil moisture, climatic changes and endogenous rhythm of cell growth. Age greatly affects the radial cell size in trees up to 30 years old. Growth rate only affects radial tracheid diameter in narrow rings of 0 to 0.5 mm. The main components of variation: soil moisture, climatic factors and a cyclic component have been estimated for pines from three different conditions of moisture: moist, moderately moist and dry. It was shown, that under optimal growth conditions the contribution of the endogenous component was more or less equal to that of the climatic component.

Dependence of Root Growth Rate on Holoploid DNA Content

2019 ◽  
Vol 50 (5) ◽  
pp. 257-260
Author(s):  
N. V. Zhukovskaya ◽  
E. I. Bystrova ◽  
N. F. Lunkova ◽  
V. B. Ivanov
Keyword(s):  
Growth Rate ◽  
Root Growth ◽  
Dna Content ◽  
Root Growth Rate

Root Growth Rate of Soybean as Affected by Drought Stress 1

1987 ◽  
Vol 79 (4) ◽  
pp. 607-614 ◽  
Author(s):  
Gerrit Hoogenboom ◽  
M. G. Huck ◽  
Curt M. Peterson
Keyword(s):  
Growth Rate ◽  
Drought Stress ◽  
Root Growth ◽  
Root Growth Rate

Maturation of the tracheary elements in the roots of Pinus banksiana and Eucalyptus grandis

2001 ◽  
Vol 79 (7) ◽  
pp. 844-849
Author(s):  
J H Taylor ◽  
C A Peterson
Keyword(s):  
Growth Rate ◽  
Root Growth ◽  
Pinus Banksiana ◽  
Eucalyptus Grandis ◽  
Tracheary Element ◽  
Reliable Indicator ◽  
Root Tip ◽  
Tracheary Elements ◽  
Fluorescent Tracer ◽  
Root Growth Rate

Tracheary elements of the xylem are responsible for the longitudinal (axial) transport of water and ions that have moved radially across the root. These vessel members and (or) tracheids mature some distance behind the root tip, and it is generally believed that this distance is directly related to root growth rate. To test this idea, the distances behind the root tip at which tracheary elements of pouch-grown Pinus banksiana Lamb. and Eucalyptus grandis W. Hill ex Maiden mature were examined. From each species, three root tip types (white, brown, and ectomycorrhizal short lateral) were assessed. Unlike previous studies of this topic, two methods of testing tracheary element maturity were employed concurrently. The first was anatomical and involved visualizing the deposition of lignin in the walls of the tracheids or vessel members. The second was functional and consisted of determining the capability of the tracheary elements to conduct a fluorescent, tracer dye. The distance behind the root tip at which the conductive xylem cells mature varied from 0.16 to 1.6 mm and was highly dependent on species and root type. No significant correlation was found between growth rate and proximity of tracheary element maturation to the tip for white roots. The presence of lignin in the tracheary element wall was not a reliable indicator of the cell's functional maturity.Key words: conductivity, development, roots, tracheary elements, xylem.

scholarly journals Effects of Light Intensity on Root Development in a D-Root Growth System

2021 ◽  
Vol 12 ◽  
Author(s):  
Yohanna Evelyn Miotto ◽  
Cibele Tesser da Costa ◽  
Remko Offringa ◽  
Jürgen Kleine-Vehn ◽  
Felipe dos Santos Maraschin
Keyword(s):  
Light Intensity ◽  
Root Growth ◽  
Root Development ◽  
Light Exposure ◽  
Light Condition ◽  
Light Response ◽  
Shoot Elongation ◽  
Growth Conditions ◽  
Auxin Signaling ◽  
Loss Of Function

Plant development is highly affected by light quality, direction, and intensity. Under natural growth conditions, shoots are directly exposed to light whereas roots develop underground shielded from direct illumination. The photomorphogenic development strongly represses shoot elongation whereas promotes root growth. Over the years, several studies helped the elucidation of signaling elements that coordinate light perception and underlying developmental outputs. Light exposure of the shoots has diverse effects on main root growth and lateral root (LR) formation. In this study, we evaluated the phenotypic root responses of wild-type Arabidopsis plants, as well as several mutants, grown in a D-Root system. We observed that sucrose and light act synergistically to promote root growth and that sucrose alone cannot overcome the light requirement for root growth. We also have shown that roots respond to the light intensity applied to the shoot by changes in primary and LR development. Loss-of-function mutants for several root light-response genes display varying phenotypes according to the light intensity to which shoots are exposed. Low light intensity strongly impaired LR development for most genotypes. Only vid-27 and pils4 mutants showed higher LR density at 40 μmol m–2 s–1 than at 80 μmol m–2 s–1 whereas yuc3 and shy2-2 presented no LR development in any light condition, reinforcing the importance of auxin signaling in light-dependent root development. Our results support the use of D-Root systems to avoid the effects of direct root illumination that might lead to artifacts and unnatural phenotypic outputs.

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