Effects of soil moisture deficits on the water relations of bambara groundnut (Vigna subterraneaL. Verdc.)

The tissue water relations of Pinusponderosa Dougl. ex Laws, (ponderosa pine) and Arctostaphylospatula Greene (greenleaf manzanita) seedlings subjected to three levels of soil moisture availability were monitored over a 6-month period. Throughout the study, osmotic potentials at full turgor and at the turgor loss point were approximately 0.5 MPa greater for pine than for manzanita. Osmotic adjustment occurred for both species as evidenced by declines in osmotic potentials at full turgor and at the turgor loss point of 0.5–0.6 MPa over the study period. Pine maintained higher bulk tissue elasticity and lower water content at the turgor loss point relative to manzanita. Moisture regime had little effect on the measured parameters except for apoplasmic water content which increased at moderate and high stress levels for both species. Results suggest that osmotic adjustment occurred, at least partially, as a result of factors other than moisture availability. The lower tissue elasticity and higher water content at the turgor loss point for manzanita suggest that the shrub species is more dependent upon high foliar water content for the maintenance of turgor compared with the conifer.

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Studies of the water relations of crop plants grown under natural rainfall in northern Australia.

Australian Journal of Agricultural Research ◽

10.1071/ar9550365 ◽

1955 ◽

Vol 6 (4) ◽

pp. 365 ◽

Cited By ~ 26

Author(s):

RO Slatyer

Keyword(s):

Soil Moisture ◽

Water Relations ◽

Internal Control ◽

Moisture Stress ◽

Grain Sorghum ◽

Atmospheric Conditions ◽

Soil Moisture Stress ◽

Natural Rainfall ◽

Dry Conditions ◽

High Level

Studies of the water relations of cotton, peanuts, and grain sorghum were made at Katherine, N.T., on crops grown under natural rainfall during the 1952-53 rainfall season. In the early part of this season, rainfall was more or less normal and little evidence of stress was seen in the plants. The latter part, however, was abnormally dry and resulted in the appearance of severe water stress symptoms in all crops. The water balance of the plants through the season was followed using Weatherley's (1950) "relative turgidity" technique of leaf turgor measurement. In each crop the relative turgidity level was maintained at a fairly high level until the onset of dry conditions, when a progressive decline commenced. This decline, although continuous, appeared to be in two stages. It was felt that the lag of absorption behind transpiration which resulted in loss of turgor was initially due to the rapid rise in transpiration, which followed the increase in atmospheric aridity with the onset of the dry period. As atmospheric conditions became more static, the continued decline in turgor was attributed primarily to the influence of soil moisture stress, in limiting absorption. Of the three crops, grain sorghum appeared to have the best-developed root system and also the most effective internal control over transpiration. Cotton appeared to be least well equipped in these respects. These features were reflected in generally higher turgor levels in grain sorghum than in other crops, and in a slower rate of decrease in turgor with the onset of dry weather. This decrease was particularly rapid in cotton. This relative resistance to turgor loss was in turn reflected in growth rate reductions in cotton as soon as soil moisture stress appeared, but not in grain sorghum until severe soil moisture stress was evident. The peanut responses throughout appeared intermediate between those of the other two crops.

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Managed Soil Moisture System for Studying Plant Water Relations under Field Conditions 1

Agronomy Journal ◽

10.2134/agronj1979.00021962007100050036x ◽

1979 ◽

Vol 71 (5) ◽

pp. 861-865 ◽

Cited By ~ 3

Author(s):

H. F. Reetz ◽

H. F. Hodges ◽

R. F. Dale

Keyword(s):

Soil Moisture ◽

Water Relations ◽

Field Conditions ◽

Plant Water Relations ◽

Plant Water

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Aspects of the water relations of spring wheat (Triticum aestivum L.) in response to induced drought

The Journal of Agricultural Science ◽

10.1017/s0021859600034766 ◽

1977 ◽

Vol 88 (2) ◽

pp. 267-282 ◽

Cited By ~ 27

Author(s):

H. G. Jones

Keyword(s):

Soil Moisture ◽

Water Relations ◽

Spring Wheat ◽

Flag Leaf ◽

Genotypic Variation ◽

Leaf Water ◽

Growth Responses ◽

Crop Water ◽

Strong Negative Correlation ◽

Mean Values

SUMMARYThis paper describes a field study of the variation in leaf water potential (ѱL), leaf conductance (gL) and other aspects of crop water relations in a set of ten spring wheats. The two main soil moisture regimes used were irrigation and drought; the latter being imposed by placing rainwater gutters between the crop rows to intercept a proportion of any rainfall. The development of plant stresses, the changes in leaf conductances during the growing season and the relationship between these variables and soil moisture depletion are described. Mean daytime leaf water potentials declined during much of the season even in well irrigated plots. There was also evidence that stomata tended to be most open during the period just prior to anthesis. Data on variation of ѱL and gL within the crop are also presented and indicate that most evaporation occurs from the flag leaf in the spring wheat canopy.Although genotypic variation was found for the mean values of ѱL and gL, interactions between variety and water regime were generally non-significant. Although yields were not well correlated with most aspects of crop water relations measured, partly because of the dominance of other factors such as maturity and disease susceptibility, a strong negative correlation was observed between yield and gL for the period 7–14 days before anthesis.Stomatal frequencies were not related to leaf conductances and there was no evidence that the stomatal behaviour adapted to previous drought stress. The growth responses observed, however, could be regarded as adaptations for reducing evaporation. The results are discussed in relation to the breeding of drought tolerant varieties of wheat.

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Soil–plant water relations of two subalpine herbs from Mount St. Helens

Canadian Journal of Botany ◽

10.1139/b88-118 ◽

1988 ◽

Vol 66 (5) ◽

pp. 809-818 ◽

Cited By ~ 8

Author(s):

David M. Chapin ◽

L. C. Bliss

Keyword(s):

Soil Moisture ◽

Water Relations ◽

Plant Water Relations ◽

Plant Water ◽

Evaporative Demand ◽

Xylem Pressure ◽

Turgor Loss Point ◽

High Maximum ◽

Tephra Deposits ◽

Mount St Helens

The subalpine environment of Mount St. Helens and other southern Cascade volcanoes is characterized by porous, pyroclastic soils and summer droughts. To evaluate plant drought stress in this environment, we examined plant water relations of Eriogonum pyrolifolium, a wintergreen, shallow-rooted, rosette perennial, and Polygonum newberryi, a deciduous, deep-rooted semierect perennial (both in Polygonaceae), at a subalpine site (elevation 1575 m) on Mount St. Helens. In a very dry summer, soil moisture below 20 cm remained above −0.1 MPa, but surface tephra deposits developed soil water potentials below −4.0 MPa. Surface tephra deposits had a mulching effect on underlying pre-eruption soils. Predawn xylem pressure potentials for adults of each species were never below −0.8 MPa, but midday xylem pressure potentials were often measured near or below the estimated turgor-loss point when vapor pressure deficits were high (maximum 3.1 kPa). Compared with Polygonum, Eriogonum had lower xylem pressure potentials, a lower turgor-loss point (mean −1.00 and −1.42 MPa, respectively), and higher conductance. In both species there was no midday depression in leaf conductance and little photosynthetic response to high evaporative demand. Thus, these species are not particularly conservative in water use and appear to rely on abundant soil moisture throughout the short growing season.

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Simulating transpiration and leaf water relations in response to heterogeneous soil moisture and different stomatal control mechanisms

Plant and Soil ◽

10.1007/s11104-015-2502-9 ◽

2015 ◽

Vol 394 (1-2) ◽

pp. 109-126 ◽

Cited By ~ 9

Author(s):

Katrin Huber ◽

Jan Vanderborght ◽

Mathieu Javaux ◽

Harry Vereecken

Keyword(s):

Soil Moisture ◽

Water Relations ◽

Leaf Water ◽

Control Mechanisms ◽

Leaf Water Relations ◽

Stomatal Control ◽

Heterogeneous Soil

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Arbuscular mycorrhizae and soil/plant water relations

Canadian Journal of Soil Science ◽

10.4141/s04-002 ◽

2004 ◽

Vol 84 (4) ◽

pp. 373-381 ◽

Cited By ~ 224

Author(s):

Robert M. Augé

Keyword(s):

Soil Moisture ◽

Stomatal Conductance ◽

Water Relations ◽

Arbuscular Mycorrhizae ◽

Glomus Intraradices ◽

Sandy Loam ◽

Characteristic Curve ◽

Mycorrhizal Symbiosis ◽

Plant Colonization ◽

Moisture Characteristic

The water relations of arbuscular mycorrhizal (AM) plants have been compared often. However, virtually nothing is known about the comparative water relations of AM and nonAM soils or about the relative influence of AM colonization of soil vs. AM colonization of plants on host water balance. In this review, I summarize findings that support the assertion that colonization of soil may play as important a role as colonization of roots regarding how AM symbiosis affects the water relations of host plants. We observed a slight but significant AM effect on the soil moisture characteristic curve of a Sequatchie fine sandy loam following 7 mo of mycorrhization by Glomus intraradices/Vigna unguiculata. In a separate study, few AM effects on either the wet or dry hysteretic curves were discernible after 12 mo of mycorrhization by G. intraradices or Gigaspora margarita on roots of Phaseolus vulgaris. Using myc- bean mutants, we determined that about half of the considerable promotion of stomatal conductance by G. intraradices and Gi. margarita was attributable to soil colonization and about half to plant colonization. A path analysis modeling approach revealed that soil hyphal colonization had larger direct and total effects on dehydration tolerance of bean than did root hyphal colonization or several other soil or plant variables. Key words: Mycorrhizal symbiosis, soil moisture characteristic, stomatal conductance, water relations

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