Morphological Responses of Geraldton Wax to Transient Soil-Water Deficit

1994 ◽  
Vol 42 (2) ◽  
pp. 205 ◽  
Author(s):  
K Akilan ◽  
JA Considine ◽  
DC Joyce ◽  
JK Marshall
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Water Status ◽  
Leaf Angle ◽  
Plant Water ◽  
Soil Water Deficit ◽  
Vertical Orientation ◽  
Flower Diameter ◽  
Linear Correlations ◽  
Chamelaucium Uncinatum

Changes in leaf angle and flower diameter of Geraldton wax (Chamelaucium uncinatum) in response to declining shoot water potential (ψshoot)) were assessed as indicators of plant water status. Leaves and petals in Geraldton wax moved vertically as ψshoot decreased. In cv. Purple Pride, the leaf angle of recently-matured, fully-expanded leaves and the diameter of fully developed flowers showed strong linear correlations with declining ψshoot (r2 = 0.90 and 0.94 respectively). The relationships were less strong when applied to almost fully expanded leaves (r2 = 0.51) and young flowers (r2 = 0.64). Older leaves showed no consistent correlation between leaf angle and ψshoot (r2 = 0.01). Similar results were observed in cvv. Alba and Lady Stephanie, but the change in orientation for a given change in ψshoot was smaller in cv. Alba than those observed in cvv. Purple Pride and Lady Stephanie. Vertical orientation of leaves and flower petals in droughted plants could be used as indicators of level of water deficit.

Comparison of Stomatal Action of Orange, Soybean and Wheat Under Field Conditions

1981 ◽  
Vol 8 (1) ◽  
pp. 65 ◽  
Author(s):  
WS Meyer ◽  
GC Green
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Water Status ◽  
Radiant Energy ◽  
Plant Water ◽  
Soil Water Deficit ◽  
Late Afternoon ◽  
Constant Rate ◽  
Orange Trees

Diurnal trends in leaf diffusive conductance, Cs, leaf water potential ΨL and rates of evapotranspiration E*T were monitored on orchard-grown orange trees and field-grown crops of soybeans and wheat. Changes in these measurements were observed on soybeans and wheat as the soil water deficit increased. Maximum values of Cs of well watered plants differed between the three species (soybeans > wheat >> orange) probably as a result of different stomatal sizes and densities. Diurnal trends in Cs were common for all species, with maximum values occurring during midmorning followed by slightly lower midday values. The reduction in Cs around midday became much more pronounced as the soil water deficit increased. Slight increases in Cs values of soybeans and wheat were recorded during late afternoon. This pattern of stomatal aperture change can reasonably be explained in terms of responses to both radiant energy and plant water status. The pattern also seems to comply with the premise that stomates interact to optimize the rate of assimilation while minimizing the rate of transpiration in a given environment. Stomatal action appeared to have little effect on daily ET in soybeans under well watered conditions; ET was closely related to incoming radiant energy. The low midday values of Cs apparently caused a midday plateau in the rate of CT in wheat while even lower daytime Cs values for orange seemed to cause a low and fairly constant rate of ET which was relatively insensitive to changes in incoming radiant energy. The value of ΨL attained during mid morning at which Cs initially began to decline was fairly constant for soybeans (-0.9 to -1.1 MPa) as the predawn ΨL decreased from -0.1 to -0.8 MPa. A similar decline in predawn ΨL for wheat caused a change in the value of ΨL at which initial decreases in Cs were observed from - 1.3 MPa to -2.4 MPa. Thus there appeared to be little adjustment of stomatal action in soybeans but considerable adjustment in wheat.

Soil–Root Interface Water Potential in Sweet Corn Affected by Organic Fertilizations and Effective Microbe Applications

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 491c-491
Author(s):  
H.L. Xu ◽  
H. Umemura ◽  
T. Higa
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Organic Materials ◽  
Sweet Corn ◽  
Water Status ◽  
Root Activity ◽  
Plant Water ◽  
Soil Water Deficit ◽  
Chemical Fertilizers

We examined effects of organic fertilizations and effective microbes (EM, mainly Lactobacillus, Rhodopseudomonas, Streptomyces, and Aspergillus) applications on soil-root interface water potential Ψs-r of `Honey-Bantam' sweet corn. The contributions to Ψs-r from root amount and root activity were analyzed using the Ohm's law. Plants were grown in 1/5000 a Wagner's pots filled with Andosol and six treatments were made as follows: 1) organic materials fermented anaerobically with EM added; 2) anaerobic organic materials; 3) organic materials fermented aerobically with EM added; 4) aerobic organic materials; 5) chemical fertilizers with EM applied, and 6) chemical fertilizers. One month after sowing, as soil water decreased, Ψs-r was maintained higher in organic fertilized plants than chemical fertilized ones and also higher in plants with EM applications than those without EM. The relatively high Ψs-r was contributed by both their large root amount and high root activity. As a consequence, photosynthesis under soil water deficit conditions were also maintained relatively high in these plants. Maintenance of a high Ψs-r favored plants to resist against water deficits. Moreover, the Ψs-r analysis is a practicable additional means to examine the soil-plant water status under undisturbed conditions.

Single hyperspectral bands are highly sensitive to water stress in adult mandarin trees

2021 ◽  
Author(s):  
Pablo Berríos ◽  
Abdelmalek Temnani ◽  
Susana Zapata ◽  
Manuel Forcén ◽  
Sandra Martínez-Pedreño ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Phase Ii ◽  
Irrigation Water ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Phase Iii ◽  
Plant Water ◽  
Severe Water Stress

<p>Mandarin is one of the most important Citrus cultivated in Spain and the sustainability of the crop is subject to a constant pressure for water resources among the productive sectors and to a high climatic demand conditions and low rainfall (about 250 mm per year). The availability of irrigation water in the Murcia Region is generally close to 3,500 m<sup>3</sup> per ha and year, so it is only possible to satisfy 50 - 60% of the late mandarin ETc, which requires about 5,500 m<sup>3</sup> per ha. For this reason, it is necessary to provide tools to farmers in order to control the water applied in each phenological phase without promoting levels of severe water stress to the crop that negatively affect the sustainability of farms located in semi-arid conditions. Stem water potential (SWP) is a plant water status indicator very sensitive to water deficit, although its measurement is manual, discontinuous and on a small-scale.  In this way, indicators measured on a larger scale are necessary to achieve integrating the water status of the crop throughout the farm. Thus, the aim of this study was to determine the sensitivity to water deficit of different hyperspectral single bands (HSB) and their relationship with the midday SWP in mandarin trees submitted to severe water stress in different phenological phases. Four different irrigation treatments were assessed: i) a control (CTL), irrigated at 100% of the ETc throughout the growing season to satisfy plant water requirements and three water stress treatments that were irrigated at 60% of ETc throughout the season – corresponding to the real irrigation water availability – except  during: ii) the end of phase I and beginning of phase II (IS IIa), iii) the first half of phase II (IS IIb) and iv) phase III of fruit growth (IS III), which irrigation was withheld until values of -1.8 MPa of SWP or a water stress integral of 60 MPa day<sup>-1</sup>. When these threshold values were reached, the spectral reflectance values were measured between 350 and 2500 nm using a leaf level spectroradiometer to 20 mature and sunny leaves on 4 trees per treatment. Twenty-four HVI and HSB were calculated and a linear correlation was made between each of them with SWP, where the ρ940 and ρ1250 nm single bands reflectance presented r-Pearson values of -0.78** and -0.83***, respectively. Two linear regression curves fitting were made: SWP (MPa) = -11.05 ∙ ρ940 + 7.8014 (R<sup>2</sup> =0.61) and SWP (MPa) = -13.043 ∙ ρ1250 + 8.9757 (R<sup>2</sup> =0.69). These relationships were obtained with three different fruit diameters (35, 50 and 65 mm) and in a range between -0.7 and -1.6 MPa of SWP. Results obtained show the possibility of using these single bands in the detection of water stress in adult mandarin trees, and thus propose a sustainable and efficient irrigation scheduling by means of unmanned aerial vehicles equipped with sensors to carry out an automated control of the plant water status and with a suitable temporal and spatial scale to apply precision irrigation.</p>

scholarly journals Microtensiometers Accurately Measure Stem Water Potential in Woody Perennials

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2780
Author(s):  
Victor Blanco ◽  
Lee Kalcsits
Keyword(s):  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Full Range ◽  
Canopy Temperature ◽  
Plant Water ◽  
Stem Water Potential ◽  
Woody Tissue ◽  
Woody Perennials ◽  
Stem Water

Stem water potential (Ψstem) is considered to be the standard measure of plant water status. However, it is measured with the pressure chamber (PC), an equipment that can neither provide continuous information nor be automated, limiting its use. Recent developments of microtensiometers (MT; FloraPulse sensors), which can continuously measure water tension in woody tissue of the trunk of the tree, can potentially highlight the dynamic nature of plant water relations. Thus, this study aimed to validate and assess the usefulness of the MT by comparing the Ψstem provided by MT with those same measurements from the PC. Here, two irrigation treatments (a control and a deficit treatment) were applied in a pear (Pyrus communis L.) orchard in Washington State (USA) to capture the full range of water potentials in this environment. Discrete measurements of leaf gas exchange, canopy temperature and Ψstem measured with PC and MT were made every two hours for four days from dawn to sunset. There were strong linear relationships between the Ψstem-MT and Ψstem-PC (R2 > 0.8) and with vapor pressure deficit (R2 > 0.7). However, Ψstem-MT was more variable and lower than Ψstem-PC when Ψstem-MT was below −1.5 MPa, especially during the evening. Minimum Ψstem-MT occurred later in the afternoon compared to Ψstem-PC. Ψstem showed similar sensitivity and coefficients of variation for both PC and MT acquired data. Overall, the promising results achieved indicated the potential for MT to be used to continuously assess tree water status.

scholarly journals Remotely Sensed Water Limitation in Vegetation: Insights from an Experiment with Unmanned Aerial Vehicles (UAVs)

2019 ◽  
Author(s):  
Kelly Easterday ◽  
Chippie Kislik ◽  
Tod E. Dawson ◽  
Sean Hogan ◽  
Maggi Kelly
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Water Content ◽  
Water Deficit ◽  
Water Status ◽  
Field Measurements ◽  
Flying Height ◽  
Plant Water ◽  
Spectral Indices ◽  
Aerial Vehicles ◽  
The Relationship

Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study, we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush), at the Blue Oak Ranch Reserve (BORR) near San Jose, California. We recorded multispectral data from the plants at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI and NDRE, and plant water content and water potential, as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit in plants and distinguish them from control and watered plants; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of plant water content than NDRE. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope) and found that PlanetScope data was able to capture the overall trend in treatments but was not able to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.

Internal Water Balance of Brigalow (Acacia harpophylla F. Muell.) Under Natural Conditions

1975 ◽  
Vol 2 (4) ◽  
pp. 489 ◽  
Author(s):  
BR Tunstall ◽  
DJ Connor
Keyword(s):  
Water Potential ◽  
Water Status ◽  
Carbon Uptake ◽  
Diurnal Changes ◽  
Plant Water ◽  
Litter Fall ◽  
Tissue Water ◽  
Diffusive Resistance ◽  
Plant Water Potential ◽  
Water Contents

On one day each month over a period of 2½ years, diurnal measurements of plant water status, leaf diffusive resistance, carbon uptake, irradiance, ambient temperature and humidity were made in a brigalow community. Diurnal changes in leaf diffusive resistance, osmotic potential, plant water potential, and carbon uptake are shown to follow general patterns and the changes in plant water potential were related to the dawn value of plant water potential. The data suggest the development of negative turgor in brigalow and demonstrate the capacity of the plant to maintain high tissue water contents at low water potentials. Measurements of shoot extension and litter fall showed that litter fall occurred principally following shoot extension.

Soybean Irrigation Initiation in Mississippi: Yield, Soil Moisture, and Economic Response

2019 ◽  
Vol 35 (1) ◽  
pp. 39-50
Author(s):  
H. C. Pringle, III ◽  
L. L. Falconer ◽  
D. K. Fisher ◽  
L. J. Krutz
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Mississippi Delta ◽  
Soil Water Potential ◽  
Irrigation Scheduling ◽  
Silty Clay ◽  
Soil Water Deficit ◽  
Soybean Yield

Abstract. Irrigated acreage is expanding and groundwater supplies are decreasing in the Mississippi Delta. Efficient irrigation scheduling of soybean [ (L.) Merr] will aid in conservation efforts to sustain groundwater resources. The objective of this study was to develop irrigation initiation recommendations for soybean grown on Mississippi Delta soils. Field studies were conducted on a deep silty clay (SiC) in 2012, 2013, 2014, and 2015 and on a deep silty clay loam (SiCL) and deep silt loam (SiL) or loam (L) soil in 2013, 2014, and 2015. Irrigation was initiated multiple times during the growing season and soybean yield and net return were determined to evaluate the effectiveness of each initiation timing. Growth stage, soil water potential (SWP), and soil water deficit (SWD) were compared at these initiation timings to determine which parameter or combination of parameters consistently predicted the resulting greatest yields and net returns. Stress conditions that reduce yield can occur at any time from late vegetative stages to full seed on these deep soils. The wide range of trigger values found for SWP and SWD to increase yields in different years emphasizes the complexity of irrigation scheduling. Monitoring soil moisture by itself or use of a single trigger value is not sufficient to optimize irrigation scheduling to maximize soybean yield with the least amount of water every year on these soils. Monitoring one or more parameters (e.g., leaf water potential, canopy temperature, air temperature, humidity, solar radiation, and wind) is needed in conjunction with soil moisture to directly or indirectly quantify the abiotic stresses on the plant to better define when a yield reducing stress is occurring. Keywords: Irrigation initiation, Irrigation scheduling, Soil water deficit, Soil water potential, Soybean, Water conservation.

Root-weighted soil water status for plant water deficit index based irrigation scheduling

2017 ◽  
Vol 189 ◽  
pp. 137-147 ◽  
Author(s):  
Xun Wu ◽  
Wenjing Zhang ◽  
Wen Liu ◽  
Qiang Zuo ◽  
Jianchu Shi ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Deficit ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Plant Water ◽  
Soil Water Status ◽  
Plant Water Deficit

THE EFFECT OF WATER DEFICIT ON N2(C2H2) FIXATION BY WHITE BEAN AND SOYBEAN

1988 ◽  
Vol 68 (4) ◽  
pp. 957-967 ◽  
Author(s):  
D. L. SMITH ◽  
M. DIJAK ◽  
D. J. HUME
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Acetylene Reduction ◽  
Physiological Responses ◽  
Plant Water ◽  
Diffusive Resistance ◽  
Drought Conditions ◽  
Plant Water Potential ◽  
White Bean

White bean (Phaseolus vulgaris L.) is generally reported to fix less N than soybean (Glycine max Merrill [L.]). Recent work has shown that in soybean the onset of physiological responses that conserve plant and soil water occurs at greater water deficits than in some other legumes. Little is known about water use regulation in white bean. Research was conducted to compare the responses of these two species to water deficit, particularly its effects on N2 fixation, in both controlled environment and field conditions. In the growth room, plant water potential, leaf diffusive resistance, acetylene reduction and nodule mass per plant were measured for both species during progressive drought, and compared to watered controls. In the field, the leaf diffusive resistance of irrigated and unirrigated plants of both species was measured, as was the soil water potential in plots where these crops were grown. Under conditions of increasing water deficit white bean reacts to conserve plant and soil water sooner than soybean: closing its stomates earlier under drought conditions and maintaining higher plant water potentials. White bean acetylene reduction declined more rapidly over time and over plant water potential levels, but not over changes in leaf diffusive resistance, than that of soybean, as the droughting progressed. In the field, under drought conditions, white bean root nodules senesced, while soybean nodules did not, and white bean was observed to exhibit more parahelionasty than soybean. The onset of physiological responses that conserve plant and soil water occurred at lesser water deficits in white bean than soybean, and this was reflected in more extreme effects on N2 fixation by white bean.Key words: White bean, soybean, water deficit, acetylene reduction, nitrogen fixation, nodulation

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