The Effects of Mechanical Stress on the Growth of Roots

Barley, KP

doi:10.1093/jxb/13.1.95

Cited by 89 publications

(60 citation statements)

References 6 publications

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“…Barley 1962Barley ,1963Waddington and Baker 1965;Isensee, Berger, and Struckmeyer 1966). In all of the instances we are aware of, however, the effect was the result of some physical or physiological impedance to growth.…”

Section: (A) the Variables Va' VI And Vsmentioning

confidence: 93%

A model of the Extension and Branching of a Seminal Root of Barley, and Its Use in Studying Relations Between Root Dimensions II. Results and Inferences From Manipulation of the Model

Hackett¹,

Rose²

1972

Aust. Jnl. Of Bio. Sci.

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A model of root growth was used to investigate why the average length (l) of cereal root members remains roughly consta,nt. Ta,king as a, standard the model root which agreed with a,ctual roots from an experiment, the nine variables in the model were a,ltered singly to see which ha,d greatest influence on 1.The results showed that the consta,ncy of 1 wa,s due primarily to the existence of ceilings to the rates at which each class of root member ca,n extend. These ceilings are thought to be determined by a property associated with the diameter of the root member. Also of importa,nce wa,s the timing of the onset of each order of bra,nching. This timing was related to that at which the parent members, as a population, began to increase roughly linearly in volume. A tentative explanation of the concomitance is put forward.Understanding of the phenomenon was advanced by the study, but a full explanation was not achieved, mainly because of the la,ck of information about certain a,spects of root development.

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Section: (A) the Variables Va' VI And Vsmentioning

confidence: 93%

A model of the Extension and Branching of a Seminal Root of Barley, and Its Use in Studying Relations Between Root Dimensions II. Results and Inferences From Manipulation of the Model

Hackett¹,

Rose²

1972

Aust. Jnl. Of Bio. Sci.

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“…Much of the research on the effect of mechanical impedance on root growth has been concerned with the behaviour of roots grown in artificial systems, such as hydroponics and glass beads, where other factors were kept constant (Gill & Miller, 1956;Barley, 1962Barley, , 1963Abdalla, Hettiaratchi & Reece, 1969;Goss, 1974;Bengough & Mullins, 19906). The pressure required to expand a root cavity in an externally pressurized cell of glass beads can be ten or more times the external pressure because of frictional resistance between the beads (Bengough & Mullins, 19906).…”

Section: Introductionmentioning

confidence: 99%

Effect of mechanical impedance on root growth and morphology of two varieties of pea (Pisum sativum L.)

Tsegaye

Mullins

1994

New Phytologist

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SUMMARYTwo pea {Pisum sativum L,) varieties (Progreta and Solara) were grown under controlled conditions for 7 or 15 days in perspex cylinders filled with moist vertniculite and for 10 days in moist sandy clay loam topsoil packed to bulk densities of 10, 12, 1-4 or 1-7 Mg m"^ (with Initial penetration resistances (PR) of: 0-037, 0101, 0-246, 0-506 and 2366 MPa respectively). The increase in PR from 0-101 to 0-506 MPa significantly decreased axis growth rate of Progreta but not of Solara. However, at a PR of 2 366 MPa, axis growth rate of Solara was reduced to significantly less than that of Progreta. Thus experiments to describe intervarietal differences in root response to nnechanical impedance need to be performed at a range of different mechanical impedances.Few, if any, laterals emerged from axes growing across large gaps between aggregates suggesting that regular stimulation of the root tip is required to trigger lateral emergence. Significant correlations (P = 0001) between first order lateral diameter and elongation rate were observed for roots of both varieties grown in moist vermiculite but not in soil. This relationship may indicate a general feature that thinner roots of any order are slower growing in a gap-free and uniformly aggregated medium.

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“…However, these systems do not simulate actual soil conditions. A more realistic approach is based on the application of pressure either directly to the growing tissue (1) or to the growth medium (2,5,12). We have adopted and modified the triaxial cell system described by CollisGeorge and Yoganathan (5) to simulate a variable mechanical stress during which ethylene production by the plants can be continuously monitored.…”

mentioning

confidence: 99%

Ethylene Evolution from Maize (Zea mays L.) Seedling Roots and Shoots in Response to Mechanical Impedance

Sarquís

Jordan²,

Morgan³

1991

Plant Physiol.

109

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The effect of mechanical impedance on ethylene evolution and growth of preemergent maize (Zea mays L.) seedlings was investigated by pressurizing the growth medium in triaxial cells in a controlled environment. Pressure increased the bulk density of the medium and thus the resistance to growth. The elongation of maize primary roots and preemergent shoots was severely hindered by applied pressures as low as 10 kilopascals. Following a steep decline in elongation at low pressures, both shoots and roots responded to additional pressure in a linear manner, but shoots were more severely affected than roots at higher pressures. Radial expansion was promoted in both organs by mechanical impedance. Primary roots typically became thinner during the experimental period when grown unimpeded. In contrast, pressures as low as 25 kilopascals caused a 25% increase in root tip diameter. Shoots showed a slight enhancement of radial expansion; however, in contrast to roots, the shoots increased in diameter even when growing unimpeded. Such morphological changes were not evident until at least 3 hours after initiation of treatment. All levels of applied pressure promoted ethylene evolution as early as 1 hour after application of pressure. After 1 hour, ethylene evolution rates had increased 10, 32, 70, and 255% at 25, 50, 75, and 100 kilopascals respectively, and continued to increase linearly for at least 10 hours. When intact corn seedlings were subjected to a series of hourly cycles of pressure, followed by relaxation, ethylene production rates increased or decreased rapidly, illustrating tight coupling between mechanical impedance and tissue response. Seedlings exposed to 1 microliter of ethylene per liter showed symptoms similar to those shown by plants grown under mechanical impedance. Root diameter increased 5 times as much as the shoot diameter. Pretreatment with 10 micromolar aminoethoxyvinyl glycine plus I micromolar silver thiosulfate maintained ethylene production rates of impeded seedlings at basal levels and restored shoot and root extension to 84 and 90% of unimpeded values, respectively. Our results support the hypothesis that ethylene plays a pivotal role in the regulation of plant tissue response to mechanical impedance.

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The Effects of Mechanical Stress on the Growth of Roots

Cited by 89 publications

References 6 publications

A model of the Extension and Branching of a Seminal Root of Barley, and Its Use in Studying Relations Between Root Dimensions II. Results and Inferences From Manipulation of the Model

A model of the Extension and Branching of a Seminal Root of Barley, and Its Use in Studying Relations Between Root Dimensions II. Results and Inferences From Manipulation of the Model

Effect of mechanical impedance on root growth and morphology of two varieties of pea (Pisum sativum L.)

Ethylene Evolution from Maize (Zea mays L.) Seedling Roots and Shoots in Response to Mechanical Impedance

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