Resistance to water movement through wheat root systems

1978 ◽  
Vol 29 (5) ◽  
pp. 913 ◽  
Author(s):  
KA Seaton ◽  
JJ Landsberg
Keyword(s):  
Water Potential ◽  
Flow Rate ◽  
Soil Type ◽  
Water Movement ◽  
Soil Water Potential ◽  
Root Systems ◽  
Experimental Period ◽  
Root Surface Area ◽  
Analogue Model ◽  
Stem Resistance

A three-layer electrical analogue model was used to calculate resistance to water movement through the roots of wheat plants growing in small weighing lysimeters. In one experiment the wheat was grown in two soil types; in a second experiment one soil type was used but different root systems were induced by controlling the water table before the start of the experimental period. Resistance calculations were based on hourly measurements of transpiration rate, leaf water potential and water uptake from three soil layers (qi), calculated from measurements of soil water potential at three depths. The number of main roots per stem (required for the model) and root surface area in each layer (Ai) were obtained from measurements of root lengths and diameters in soil cores taken at the end of each experiment. Estimates of the resistance to flow through stems led to estimates of ψ0), the water potential at the stem base, at any stem flow rate. Axial (main) root resistances (Rxi) were calculated from the Poiseuille equation. Values of the resistance to water movement through the roots in layer i were calculated from the set of equations describing uptake from each layer in terms of flow rates, potential gradients and resistances; these values, inserted in the solution for 1/10 from the set of three equations, yielded total root resistances (RT) and estimates of the effective soil moisture potential (^ψs) for the whole profile. (RT) ranged from 63.9 to 627.3 bar sec mm-3 (cf. stem resistance between 24 and 70 bar sec mm-3) and was inversely related to flow rate through the main roots, which indicated a constant potential drop (^ψs – ψ0) of about 10 bars, irrespective of soil type or root system. Radial root resistances, estimated as At(<ψsi – ψ0)/qi, ranged from 4.6 x 104 to 4.2 x 106 bar sec mm-l and were inversely related to qi. Inaccuracies in estimates of Rxi do not affect the results much and the model used is potentially valuable as a framework for field research.

EFFECT OF SOIL WATER POTENTIAL AND BULK DENSITY ON WATER UPTAKE PATTERNS AND RESISTANCE TO FLOW OF WATER IN WHEAT PLANTS

1971 ◽  
Vol 51 (2) ◽  
pp. 211-220 ◽  
Author(s):  
S. J. YANG ◽  
E. DE JONG
Keyword(s):  
Water Potential ◽  
Bulk Density ◽  
Soil Water ◽  
Water Uptake ◽  
Water Movement ◽  
Soil Column ◽  
Soil Water Potential ◽  
Moisture Uptake ◽  
The Mathematical Model ◽  
Water Uptake Patterns

Water uptake patterns of wheat plants were studied in a growth chamber by using two soils packed to three different bulk densities. The resistances to water movement in the soil and in the plant were calculated from the mathematical model for water uptake published in the literature. When the capillary potential of the soils was near −⅓ bar, withdrawal of water by plants was relatively small and most of the water was taken from the top 25 cm of the soil column. As soil water potential decreased, water uptake increased progressively toward the lower part of the soil column. The resistance to water movement in the plant increased from the top to the bottom of the root system and increased with increasing bulk density of the soils. For wet soils, unrealistic values were obtained which could be due to the fact that the interaction between aeration and moisture uptake is not taken into account in the theoretical equations for moisture uptake.

Soil type does not affect seed ageing when soil water potential and temperature are controlled

2009 ◽  
Vol 320 (1-2) ◽  
pp. 131-140 ◽  
Author(s):  
Rowena L. Long ◽  
Kathryn J. Steadman ◽  
F. Dane Panetta ◽  
Stephen W. Adkins
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Type ◽  
Soil Water Potential ◽  
Seed Ageing

scholarly journals Onion Response to Drip Irrigation Intensity and Emitter Flow Rate

2005 ◽  
Vol 15 (3) ◽  
pp. 652-659 ◽  
Author(s):  
Clinton C. Shock ◽  
Erik B.G. Feibert ◽  
Lamont D. Saunders
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Flow Rate ◽  
Total Yield ◽  
Soil Water Potential ◽  
Marketable Yield ◽  
Flow Rates ◽  
Irrigation Intensity ◽  
Significant Difference ◽  
Very High

Although an irrigation onset criterion for drip-irrigated onion (Allium cepa) has been determined, the optimal irrigation intensity has not been examined. Some authors have argued that very high irrigation frequencies with low amounts of water are needed to maximize crop responses. Long-day, sweet Spanish onions were grown on 44-inch beds with two double rows spaced 1.8 ft apart and a drip tape buried 4 inches deep in the bed center. Onions were submitted to eight treatments as a combination of four irrigation intensities (1/16, 1/8, 1/4, and 1/2 inch of water per irrigation) and two drip tape emitter flow rates (0.5 and 0.25 L·h–1) on silt loam in 2002 and 2003. The 1/16-, 1/8-, 1/4-, and 1/2-inch irrigation intensities had irrigations scheduled up to eight times, four times, twice, or once per day, respectively, to replenish soil water potential to –20 cbar as needed. Each plot was independently and automatically irrigated if the soil water potential at 8-inch depth was equal to or lower than –20 cbar. This resulted in an average of 564, 269, 121, and 60 irrigations over 107 days for the 1/16-, 1/8-, 1/4-, and 1/2-inch irrigation intensities, respectively. Onions were harvested, stored, and evaluated for yield and grade after 75 days of storage. Averaged over irrigation intensities, the drip tape with 0.5 L·h–1 emitters had significantly higher total yield, marketable yield, and colossal onion yield than the tape with 0.25 L·h–1 emitters. Averaged over emitter type, the 1/2-inch irrigation intensity had higher total and marketable onion yields than the 1/16- and 1/8-inch intensities. Averaged over emitter type, the 1/2-inch irrigation intensity resulted in the highest super colossal and colossal onion yield. Onions grown with an irrigation intensity of 1/2 inch and drip tape with emitter flow rate of 0.5 L·h–1 produced total yields of 50.0 ton/acre, marketable yields of 48.8 ton/acre, super colossal yield of 1.05 ton/acre, and colossal yield of 13.9 ton/acre. Interactions between irrigation intensities and emitter flow rates were nonsignificant for the number of irrigations, water applied, average soil water potential, or onion yield and grade. There was no significant difference in average soil water potential between treatments. There was no significant difference in total water applied plus precipitation between treatments, with, on average, 32.3 and 31.1 inches applied in 2002 and 2003, respectively. Onion evapotranspiration from emergence to onion lifting totaled 34.6 and 37.3 inches in 2002 and 2003, respectively.

scholarly journals SUSCETIBILIDADE À INTRUSÃO RADICULAR DE GOTEJADORES CONVENCIONAIS NA IRRIGAÇÃO SUBSUPERFICIAL DE CANA-DE-AÇÚCAR

Irriga ◽  
2004 ◽  
Vol 9 (2) ◽  
pp. 150-165 ◽  
Author(s):  
Ronaldo Souza Resende ◽  
Rubens Duarte Coelho ◽  
Maria De Lourdes da Silva Leal ◽  
Samuel Silva da Mata
Keyword(s):  
Water Potential ◽  
Flow Rate ◽  
Sugar Cane ◽  
Drip Irrigation ◽  
Soil Water Potential ◽  
Soil Surface ◽  
Irrigation Frequency ◽  
Irrigation Level ◽  
Different Depths ◽  
Subsurface Drip

SUSCETIBILIDADE À INTRUSÃO RADICULAR DE GOTEJADORES CONVENCIONAIS NA IRRIGAÇÃO SUBSUPERFICIAL DE CANA-DE-AÇÚCAR   Ronaldo Souza Resende1; Rubens Duarte Coelho1; Maria de Lourdes da Silva Leal2; Samuel Silva da Mata21Departamento de Engenharia Rural, Escola Superior de Agricultura, Universidade de São Paulo,  Piracicaba,  SP, [email protected] de Pesquisa Agropecuária dos Tabuleiros Costeiros, Aracaju, SE.    1 RESUMO  Foram avaliados, quanto à ocorrência do processo de intrusão de raízes sob irrigação subsuperficial, sete modelos de gotejadores, sendo esses submetidos a duas profundidades de instalação no solo, P15 (0,15m) e P30 (0,3m), e três condições de enraizamento para a cultura da cana-de-açúcar: a) Úmido, no qual o solo era irrigado quando o potencial da água no solo alcançava -30 kPa b) Seco, quando esse potencial atingia -80 kPa e c) Sem Cultivo (SC), usado como controle e com esquema de irrigação idêntico ao tratamento Úmido. O experimento foi conduzido em vasos e em condição de estufa. A vazão dos gotejadores foi medida mensalmente e por um período de 270 dias, o que correspondeu ao ciclo completo da cultura. Os resultados evidenciaram diferenças estatisticamente significativas entre os modelos avaliados e indicaram não ser o regime de umidade do solo determinante para a ocorrência da intrusão de raízes nos gotejadores.  UNITERMOS: gotejamento; intrusão de raízes; entupimento    RESENDE, R. S.; COELHO, R. D.; LEAL, M. de L. da S.; MATA, S. S. da ROOT INTRUSION SUSCEPTIBILITY OF CONVENTIONAL DRIPPERS IN SUBSUPERFICIAL DRIP IRRIGATION OF SUGAR CANE CROP   2 ABSTRACTS  In order to evaluate root intrusion potential in subsurface drip irrigation (SDI) of sugar cane crop, seven emitters were tested under controlled environment (greenhouse and vase conditions). The drippers were installed at two different depths: 0.15m and 0.30m from soil surface (P15 and P30) and analyzed under three watering conditions: 1. Moist :  irrigation  started when the water potential in soil reached -30 kPa (tensiometer);  2. Dry: irrigation started when the water potential in soil reached -80 kPa; and 3. No crop / Moist (NOC): where the vases were kept without any crop (Control) with the same irrigation level of condition 1, isolated from other factors, which could disturb emitters flow rate.  Flow rate readings were taken every month in the sugar cane crop (270 days cycle). The results showed remarkable statistically significant differences among tested emitters. Irrigation frequency and soil water potential did not show significant correlation to root intrusion inside the buried emitters.  KEYWORDS: Drip irrigation; root intrusion; clogging

Soil and plant resistances to water absorption by plant root systems

1979 ◽  
Vol 30 (2) ◽  
pp. 279 ◽  
Author(s):  
GJ Burch
Keyword(s):  
Water Absorption ◽  
Root System ◽  
Soil Water ◽  
Water Movement ◽  
Plant Root ◽  
Unit Length ◽  
Water Flux ◽  
Soil Water Potential ◽  
Root Systems ◽  
Soil Resistance

A study of water absorption by root systems of two herbage species, white clover (Trifolium repens L.) and tall fescue (Festuca arundinacea Schreb.), was used to partition the resistances to water flux between the soil and plant. A large and almost constant plant resistance influenced the pattern of water absorption until the soil resistance reached about 1.5 x 103 MPa s cm-3. This corresponded to an extraction of almost 80% of the available soil water. Water absorption from progressively deeper soil layers showed no evidence of any substantial resistance to water flux through the root xylem. Therefore, in wet soils, water movement into and through a root system is predominantly influenced by a large resistance to the radial water flux through root tissues outside the xylem. The radial resistance values for unit (cm) length of root were 6.49 x 106 and 6.54 x 106 MPa s cm-2 for clover and fescue respectively. A model of water uptake has been described which introduces two modified parameters for integrating the soil water potential (ψ) and the soil-root conductance (κ), over an entire root system. This study, along with other evidence from the literature, would indicate that for unit length of root the radial resistance to water absorption is reasonably similar, not only for an entire root system but also for a number of different species. An underestimation of the radial soil resistance (Rsr) to water absorption suggests that a root contact resistance (Rc) exists which could be due to the shrinkage of the soil or root, or both, with drying of the soil. This effect caused an increase in resistance to water absorption of about 48 x Rsr for fescue and 71 x Rsr for clover. This difference in Rc between the two species was attributed to a contrast in root morphology, especially a difference in the average root diameters of the two species.

Response of the components of sugar beet leaf water potential to a drying soil profile

1987 ◽  
Vol 109 (3) ◽  
pp. 437-444 ◽  
Author(s):  
Kay F. Brown ◽  
M. McGowan ◽  
M. J. Armstrong
Keyword(s):  
Sugar Beet ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Osmotic Potential ◽  
Seasonal Changes ◽  
Water Movement ◽  
Soil Water Potential ◽  
Leaf Water ◽  
Leaf Osmotic Potential

SummaryFor many field-grown crops, including sugar beet, there is little information on the seasonal changes in leaf water potential and its components as the soil dries. Therefore, seasonal changes in leaf water, osmotic and turgor potentials of sugar beet were measured in two seasons, in crops that experienced differing degrees of soil moisture stress. In 1983 potentials of crops exposed to early and late droughts were compared with those of irrigated crops, and in 1984 measurements were made in a non-irrigated crop. In the irrigated crop the midday leaf water potential changed little during the season, except in response to fluctuating evaporative demand. In the drought and non-irrigated treatments there was a sharp fall in leaf water potential as soon as the soil water potential decreased. The size of the midday leaf water potential was primarily determined by soil dryness. However, the leaf water potential did not decrease below about — 1·5 MPa in either year. The leaf osmotic potential declined at the same time as the leaf water potential, but the extent to which this happened differed in the two years. Only in the 1984 non-irrigated crop did the osmotic potential continue to decrease as the soil dried, suggesting that osmotic adjustment had taken place in 1984 but not in 1983. Thus higher turgor was maintained in the 1984 crop than in the 1983 drought-affected crops. Some turgors were recorded as apparently negative in 1983.Since the leaf water potential declined to a minimum of about — 1·5 MPa, the soil water potential minima were also about — 1·5 MPa. However, deeper soil was not dried to this extent, suggesting that the extra resistance for water uptake from deep soil was limiting or the rooting density was too low.The pattern of recovery of leaf water potential overnight suggested that the rhizosphere resistance to water movement was small, even as the soil dried. However, measurement of stem water potentials in 1984 indicated that a significant resistance to water flow existed within the aerial part of sugar beet plants. This shows that the use of the water potential in leaves as an estimate of that in stems or roots can be misleading.

Effect of Soil Water Potential of Two Soils on Soybean Emergence 1

1979 ◽  
Vol 71 (6) ◽  
pp. 980-982 ◽  
Author(s):  
L. G. Heatherly ◽  
W. J. Russell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential

scholarly journals A Data-Driven Method for the Temporal Estimation of Soil Water Potential and Its Application for Shallow Landslides Prediction

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1208
Author(s):  
Massimiliano Bordoni ◽  
Fabrizio Inzaghi ◽  
Valerio Vivaldi ◽  
Roberto Valentino ◽  
Marco Bittelli ◽  
...  
Keyword(s):  
Machine Learning ◽  
Water Potential ◽  
Soil Water ◽  
Temporal Trends ◽  
Soil Water Potential ◽  
Shallow Landslides ◽  
Water Dynamics ◽  
Data Driven ◽  
Machine Learning Techniques ◽  
Physically Based

Soil water potential is a key factor to study water dynamics in soil and for estimating the occurrence of natural hazards, as landslides. This parameter can be measured in field or estimated through physically-based models, limited by the availability of effective input soil properties and preliminary calibrations. Data-driven models, based on machine learning techniques, could overcome these gaps. The aim of this paper is then to develop an innovative machine learning methodology to assess soil water potential trends and to implement them in models to predict shallow landslides. Monitoring data since 2012 from test-sites slopes in Oltrepò Pavese (northern Italy) were used to build the models. Within the tested techniques, Random Forest models allowed an outstanding reconstruction of measured soil water potential temporal trends. Each model is sensitive to meteorological and hydrological characteristics according to soil depths and features. Reliability of the proposed models was confirmed by correct estimation of days when shallow landslides were triggered in the study areas in December 2020, after implementing the modeled trends on a slope stability model, and by the correct choice of physically-based rainfall thresholds. These results confirm the potential application of the developed methodology to estimate hydrological scenarios that could be used for decision-making purposes.

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