Absorption of Soil Moisture by Maize Roots

Davis, Charles H.F.

doi:10.1086/334915

Cited by 33 publications

(22 citation statements)

References 3 publications

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“…The changes in the water content calculated in this chapter are in agreement with the calculations conducted by Bengough [10], which report that after initial fast transients, the water saturation equilibrates and thus uptake by roots stops in the soils where there isn't any resupply of water (see Figure 8.7 for W = 0). Similar water saturation profiles presented in Figure 8.7 for W = 0 and in Bengough [10] have been measured experimentally by Davis [26]. In the case of average seasonal rainfall two pseudo-equilibrium regions can develop (see Figure 8.7).…”

Section: Discussionsupporting

confidence: 80%

A mathematical model of plant nutrient uptake

Koebernick¹,

Fowler²,

Darrah

2001

Journal of Mathematical Biology

113

159

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This thesis deals with the mathematical modelling of nutrient uptake by plant roots. It starts with the Nye-Tinker-Barber model for nutrient uptake by a single bare cylindrical root. The model is treated using matched asymptotic expansion and an analytic formula for the rate of nutrient uptake is derived for the first time. The basic model is then extended to include root hairs and mycorrhizae, which have been found experimentally to be very important for the uptake of immobile nutrients. Again, analytic expressions for nutrient uptake are derived. The simplicity and clarity of the analytical formulae for the solution of the single root models allows the extension of these models to more realistic branched roots. These models clearly show that the "volume averaging of branching structure" technique commonly used to extend the Nye-Tinker-Barber with experiments can lead to large errors. The same models also indicate that in the absence of large-scale water movement, due to rainfall, fertiliser fails to penetrate into the soil. This motivates us to build a model for water movement and uptake by branched root structures. This model considers the simultaneous flow of water in the soil, uptake by the roots, and flow within the root branching network to the stems of the plant. The water uptake model shows that the water saturation can develop pseudo-steadystate wet and dry zones in the rooting region of the soil. The dry zone is shown to stop the movement of nutrient from the top of the soil to the groundwater. Finally we present a model for the simultaneous movement and uptake of both nutrients and water. This is discussed as a new tool for interpreting available experimental results and designing future experiments. The parallels between evolution and mathematical optimisation are also discussed.

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Section: Discussionsupporting

confidence: 80%

A mathematical model of plant nutrient uptake

Koebernick¹,

Fowler²,

Darrah

2001

Journal of Mathematical Biology

113

159

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“…It is consistent with observations on soil drying by maize like those of Davis (1940). He grew maize plants at one end of glass-fronted boxes that had tensiometers placed in the soil every 5 cm along the box, and monitored the growth of the roots and the drying of the soil.…”

Section: Relative Contributions Of Axes and Branches To Water Collectionsupporting

confidence: 84%

Rates of water uptake into the mature root system of maize plants

1993

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SUMMARYA new method of measuring water uptake by roots is applied to whole root systems of large maize plants growing in aeroponic (mist) culture. The method depends on the build-up of concentration of dye (sulphorhodamine G) on and in the root surface, when it is fed in the mist. Water enters the roots rapidly, but the dye is separated from the water by osmotic filtration and penetrates the apoplast only by very slow diffusion. The dye accumulates progressively with time on roots on transpiring plants, but not on roots of non-transpiring controls. The rate of accumulation of dye at a place on the root is translated to a flux of water into the root at that place, using the concentration of dye in the mist. Water fluxes were measured into first-order branches and axes over the root system and expressed both as fluxes per unit length and per unit surface of root. Values are consistent with those found by potometric methods for limited samples of young plants. The variance of the measurements is quite large, possibly reflecting real heterogeneities in water uptake throughout the root system. The maximum water uptake achieved by a few branches was 40 //I h"^ cm ' root. On average, flux into axes and branches was the same throughout the root system, at about 5 //I h"^ cm"-. The region of the axis at which the late metaxylem vessels mature and become conducting coincides with the region where the branches become active in water uptake (20-30 cm from the tip). Proximal to this, the branches collect about eight times as much water as the axis, having about eight times the surface area. The zone of maximum water collection by branches and axis is 30-60 cm from the tip (6-8 //I h~' cm~^ axis). In the older, more proximal regions, water collection drops to about a quarter of this.

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“…It is suggested that this is because the movement of moisture in the soil is so slow that the roots of actively transpiring plants cause a zone of dryness to develop around themselves. That such a drying out in the neighbourhood of roots does occur has been demonstrated by Aldrich, Work & Lewis (1935) ' Davis (1940) and Richards & Loomis (1942). It was the potential of the water in these dried zones and not of the soil as a whole which was reflected in the plant.…”

Section: Discussionmentioning

confidence: 83%

Studies in the Water Relations of the Cotton Plant

Weatherley

1951

New Phytologist

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Absorption of Soil Moisture by Maize Roots

Cited by 33 publications

References 3 publications

A mathematical model of plant nutrient uptake

A mathematical model of plant nutrient uptake

Rates of water uptake into the mature root system of maize plants

Studies in the Water Relations of the Cotton Plant

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