Physics of Root Growth

Greacen, EL; Oh, J. S.

doi:10.1038/newbio235024a0

Cited by 232 publications

(131 citation statements)

References 8 publications

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“…Effects on growth often are attributed to this turgor loss (2,16). However, the discovery that plants adjust osmotically to low *I' (14,23) was followed by reports that turgor was maintained, sometimes completely, while growth was inhibited (12,13,20,21,24,25,33). Ifturgor does not fall, the growth inhibition must be attributed to other factors.…”

mentioning

confidence: 99%

Turgor and Growth at Low Water Potentials

Nonami¹,

Boyer²

1989

Plant Physiol.

131

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Turgor affects cell enlargement but has not been measured in enlarging tissue of intact plants when growth is inhibited by inadequate water. Mature or excised tissue can be problematic for these measurements because turgor may not be the same as in intact enlarging cells. Therefore, we measured the average turgor in the elongating region of intact stems of soybean (Glycine max [L.] Merr.) while the seedlings were exposed to low water potentials by transplanting to vermiculite of low water content. Stem growth was completely inhibited by the transplanting, and the average turgor decreased in the mature stem tissue. However, it did not decrease in the elongating region whether measured in intact or excised tissue (total of four methods). At the cellular level, turgor was uniform in the elongating tissue except at transplanting, when turgor decreased in a small number of cortical cells near the xylem. The reduced turgor in these cells, but constant turgor in most of the cells, confirmed that no general turgor loss had occurred but indicated that gradients in water potential extending from the xylem into the enlarging tissue were reduced, thus decreasing the movement of water into the tissue for cell enlargement. A modest growth recovery occurred after 2 days and was preceded by a recovery of the gradient. This suggests that under these conditions, growth initially was inhibited not by turgor loss but by a collapse of the water potential gradient necessary for the growth process.Plants grow in size mostly by increasing in cell water content. The enlargement occurs because solute concentrations are high enough inside the cells to extract water osmotically from the surroundings. As a result, the pressure in the cells (turgor) rises and extends the walls irreversibly, enlarging the cell compartment.The dependency of these processes on water causes growth to respond to the supply of water in the soil. Effects are particularly apparent for organs in the shoot, which may be inhibited during vegetative or reproductive development (33) with large consequences for plants.The depletion of soil water decreases water potentials ('') in the plant and also can decrease the turgor. Effects on growth often are attributed to this turgor loss (2, 16). However, the discovery that plants adjust osmotically to low *I' (14, 23) was followed by reports that turgor was maintained, sometimes completely, while growth was inhibited (12,13,20,21,24,25,33). Ifturgor does not fall, the growth inhibition must be attributed to other factors. Several possibilities have been suggested (3,7,20,32) but doubt exists because the turgor measurements (12,13,20,21,24,25,33) involved excised tissue, sometimes from nongrowing parts of the plant.

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confidence: 99%

Turgor and Growth at Low Water Potentials

Nonami¹,

Boyer²

1989

Plant Physiol.

131

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“…To answer this we have adopted an approach rates are often more dependent on soil strength than which relies on specially constructed growth cells on soil water status, within defined boundaries, as that allow manipulation of the strength of growth measured by soil matric potential (Taylor & Ratliff, media, without altering their water or nutritional 1969;Greacen & Oh, 1972).…”

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Mechanical impedance of root growth directly reduces leaf elongation rates of cereals

Young¹,

Montagu

Conroy

et al. 1997

New Phytologist

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SUMMARYA dry soil is generally a hard soil. Thus, the effects of water stress and mechanical impedance on plant growth are difficult to separate. To achieve this we have developed a growth cell that allows manipulation of the strength of growth media (i.e. mechanical impedance) without altering the availability of water or nutrients. We monitored leaf elongation rates of barley and wheat seedlings before and after the mechanical impedance to root growth was increased. Results show that a large and rapid reduction (within 10 min) of leaf elongation rates occurred after impedance to the roots was increased. The average reductions for barley and wheat, with associated standard errors, were 22-6% (4-84) and 36-2% (548), respectively. The data are consistent with the hypothesis that mechanical impedance of roots might have a direct negative effect on leaf growth even where nutrients and water are in plentiful supply to the plant. The implications of the rate of the response are examined with respect to the underlying mechanisms controlling root-shoot signalling.

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“…By contrast, Benjamin and Nielsen (2006) observed increased soybean root area under adequate soil water availability. Root growth response to drought is determined by several factors such as water deficit intensity, water deficit timing regarding crop stage (HOOGENBOOM et al, 1987), soil restrictive conditions to root growth (BENGOUGH et al, 2011;BUSSCHER et al, 1997;GREACEN;OH, 1972;SPONCHIADO et al, 1989), and soybean genotype (HUDAK;PATTERSON, 1996).…”

Section: With Water Deficitmentioning

confidence: 99%

“…Root growth response to water stress is associated to various factors such as cultivar (HUDAK; PATTERSON, 1996), deficit timing in relation to soybean growth stage (HOOGENBOOM et al, 1987), and soil physical (BEUTLER;CENTURION, 2004;GREACEN;OH, 1972;RICHART et al, 2005), chemical (SPONCHIADO et al, 1989) or biological (BENGOUGH et al, 2011) limitations to root growth. In this context, it is said that soil mechanical resistance to root growth varies directly with the soil bulk density, and inversely with the soil water content (KLEIN et al, 2006;MORAES et al, 2014;VAZ et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Root growth of soybean cultivars under different water availability conditions

Franchini

Balbinot

Debiasi

et al. 2017

SCA

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Vigorous growth of soybean root system is a desired trait in breeding programs. However, few studies have evaluated this feature under field conditions. The aim of this research was to evaluate root growth of eight soybean cultivars under different water availability conditions. The experiment was carried out in Londrina, Paraná state, Brazil, during two growing seasons -with and without water deficit during the vegetative period. Soybean roots were sampled at flowering and assessed for dry matter yield, area and length at 0-0.25; 0.25-0.50; 0.50-0.75 and 0.75-1.00 m depth ranges. On average, root length and area of the cultivars Embrapa 48 and BRS 284 under water deficit were 66% and 40% larger than the others at 0.25-0.50 and 0.50-0.75 m layers, respectively. Under suitable water supply, BRS 282 showed the highest root length and area. Apart from the cultivars Embrapa 48, BRS 284, and BRS 255RR, soybean root growth was mostly lower under water deficit throughout the vegetative stage, which might been due to a higher soil resistance to root penetration, resulting from low soil water content. Drought increased the proportion of soybean roots at subsoil layers, mainly for Embrapa 48 and BRS 284. The cultivars Embrapa 48 and BRS 284 are promising to be used in breeding programs targeting superior root growth in subsoil layers. Key words: Glycine max L. Root area. Root length. Root mass. ResumoO crescimento vigoroso do sistema radicular da soja é uma característica almejada nos programas de melhoramento genético. No entanto, há poucos trabalhos na literatura que avaliaram essa característica em condição de campo. O objetivo dessa pesquisa foi avaliar o crescimento de raízes de oito cultivares de soja em diferentes situações de disponibilidade hídrica. O experimento foi conduzido em Londrina, PR, em duas safras, uma com déficit hídrico no período vegetativo e outra sem déficit. As raízes da soja foram amostradas no florescimento e avaliadas quanto à massa seca, área e comprimento, nas camadas de 0-0,25; 0,25-0,50; 0,50-0,75; e 0,75-1,00 m. Na safra com déficit hídrico, o comprimento e área radicular das cultivares Embrapa 48 e BRS 284 foram, em média, 66% e 40% maiores do que as demais cultivares nas camadas de 0,25-0,50 e 0,50-0,75 m, respectivamente. Com adequada disponibilidade hídrica, a cultivar BRS 282 apresentou o maior comprimento e área radicular. Excetuando-se as cultivares Embrapa 48, BRS 284 e BRS 255RR, o crescimento radicular foi geralmente menor na safra com ocorrência de seca no estádio vegetativo, provavelmente em razão da maior resistência do solo à penetração das raízes. A seca aumentou a proporção de raízes em camadas mais profundas, principalmente na Embrapa 48 e BRS 284. As cultivares Embrapa 48 e BRS 284 são promissoras para a obtenção de linhagens com maior crescimento radicular em camadas subsuperficiais. Palavras-chave: Glycine max L. Área de raízes. Comprimento de raízes. Massa de raízes.

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Physics of Root Growth

Cited by 232 publications

References 8 publications

Turgor and Growth at Low Water Potentials

Turgor and Growth at Low Water Potentials

Mechanical impedance of root growth directly reduces leaf elongation rates of cereals

Root growth of soybean cultivars under different water availability conditions

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