scholarly journals Germination of rye brome (Bromus secalinus L.) seeds under simulated drought and different thermal conditions

2014 ◽  
Vol 66 (4) ◽  
pp. 157-164
Author(s):  
Małgorzata Haliniarz ◽  
Jan Kapeluszny ◽  
Sławomir Michałek
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Gravimetric Method ◽  
Thermal Conditions ◽  
Initial Growth ◽  
Air Humidity ◽  
Bromus Secalinus ◽  
Simulated Drought

The aim of the present study was to compare the germination of rye brome (<em>Bromus secalinus </em>L.) seeds and the initial growth of seedlings under simulated drought and different thermal conditions. The study included two experiments carried out under laboratory conditions in the spring of 2012. The first experiment involved an evaluation of the speed of germination as well as of the biometric characters and weight of seedlings in polyethylene glycol solutions (PEG 8000) in which the water potential was: -0.2; -0.4; -0.65; -0.9 MPa, and in distilled water as the control treatment. The experiment was conducted at the following temperatures: 25/22oC and 18/14oC day/night, at a relative air humidity of 90%. The other experiment, in which lessive soil was used as a germination substrate, was carried out in a plant growth chamber at two levels of air humidity (55–65% and 85–95%) and temperature (22/10oC and 16/5oC). The soil moisture content was determined by the gravimetric method and the water potential corresponding to it was as follows: -0.02, -0.07, -0.16, -0.49, -1.55 MPa. The germination capacity and emergence of <em>Bromus secalinus </em>as well as the weight of sprouts produced were significantly dependent on the water potential of the polyethylene glycol solution and on the soil water potential. The emergence of <em>Bromus secalinus </em>was completely inhibited by reducing the soil water potential below -0.16 MPa (the point of strong growth inhibition). The emergence and biometric characters of rye bro- me seedlings were significantly dependent on temperature and air humidity.

scholarly journals Soil Moisture Sensor Test with Mississippi Delta Soils

2019 ◽  
Vol 62 (2) ◽  
pp. 363-370
Author(s):  
Ruixiu Sui ◽  
Horace C. Pringle ◽  
Edward M. Barnes
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Measurement Accuracy ◽  
Mississippi Delta ◽  
Soil Water Potential ◽  
Gravimetric Method ◽  
Irrigation Scheduling

Abstract. One of the methods for irrigation scheduling is to use sensors to measure the soil moisture level in the plant root zone and apply water if there is a water shortage for the plants. The measurement accuracy and reliability of the soil moisture sensors are critical for sensor-based irrigation management. This study evaluated the measurement accuracy and repeatability of the EC-5 and 5TM soil volumetric water content (SVWC) sensors, the MPS-2 and 200SS soil water potential (SWP) sensors, and the 200TS soil temperature sensor. Six 183 cm × 183 cm × 71 cm wooden compartments were built inside a greenhouse, and each compartment was filled with one type of soil from the Mississippi Delta. A total of 66 sensors with 18 data loggers were installed in the soil compartments to measure SVWC, SWP, and soil temperature. Soil samples were periodically collected from the compartments to determine SVWC using the gravimetric method. SVWC measured by the sensors was compared with that determined by the gravimetric method. The SVWC readings from the sensors had a linear regression relationship with the gravimetric SVWC (r2 = 0.82). This relationship was used to calibrate the sensor readings. The SVWC and SWP sensors could detect the general trend of soil moisture changes. However, their measurements varied significantly among the sensors. To obtain accurate absolute soil moisture measurements, the sensors require individual and soil-specific calibration. The 5TM, MPS-2, and 200TS sensors performed well in soil temperature measurement tests. Individual temperature readings from these sensors were very close to the mean of all sensor readings. Keywords: Irrigation, Sensors, Soil types, Soil water content, Soil water potential.

scholarly journals Effects of soil moisture on the germination and emergence of sugar beet (beta vulgaris l.)

1975 ◽  
Vol 47 (1) ◽  
pp. 1-70 ◽  
Author(s):  
Erkki Aura
Keyword(s):  
Soil Moisture ◽  
Polyethylene Glycol ◽  
Sugar Beet ◽  
Water Potential ◽  
Soil Water ◽  
Water Intake ◽  
Seedling Emergence ◽  
Soil Water Potential ◽  
Permeable Membrane ◽  
Low Water Potential

By means of theoretical calculations and laboratory experiments, this study attempted to elucidate the effects of excessive and of inadequate soil moisture on the germination and seedling emergence of sugar beet. The results of this study confirmed the opinion that water contained in the sugar beet seed or surrounding the seed as a water film is a barrier to the adequate intake of oxygen by the seed only when the value of the water potential is close to zero. The soil water potential at which the passage of oxygen into the seed is prevented depends largely on the structure of the seed bed. With a semi-permeable membrane of cellulose acetate and a solution of polyethylene glycol, it was shown that the sugar beet seed will still germinate fairly well at a potential of —10 atm, but at —13 atm germination is slight. The soil water potential appeared to have nearly the same effect on germination as did the water potential of the polyethylene glycol solution. The seedling emergence percentage was, however, smaller than the germination percentage in experiments with the semi-permeable membrane. This was considered to be caused by the slow extension growth of the radicle due to a low water potential, at the stage of seedling emergence. According to studies made, the initial water intake of the sugar beet seed planted in soil is rapid. Poor contact between the seed and the soil slows down water intake and seedling emergence, but does not impair the final seedling emergence. Removal of the fruit coat was shown to improve germination markedly when the water potential is low. This treatment would have little practical significance, since the growth of the radicle at a low water potential is very slow.

Vegetative Growth Distribution During Water Deficits in Vitis vinifera L

1988 ◽  
Vol 15 (5) ◽  
pp. 641 ◽  
Author(s):  
HR Schultz ◽  
MA Matthews
Keyword(s):  
Growth Inhibition ◽  
Vitis Vinifera ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Vitis Vinifera L ◽  
Initial Growth ◽  
Growth Responses ◽  
Time Duration ◽  
Water Deficits

The expansion of plant organs is inhibited by water deficits but the effect of ontogeny on growth sensitivity is not known. Therefore, growth responses of shoot organs (internodes, leaves, tendrils) of Vitis vinifera L. cv. White Riesling to developing water deficit were investigated under controlled environmental conditions. Growth of organs at a node position was asynchronous, with internode growth being more restricted than leaf and tendril growth in time (duration of growth) and space (number of node positions at which growth occurred). The timing of initial growth inhibition and final growth cessation caused by soil water deficits was identical in internodes, leaves, and tendrils. The degree of growth inhibition at low water potential was similar among organs, whether linear or volume changes were considered and whether the most rapidly expanding organs or organs of similar developmental stage were compared. In addition, the relative partitioning of growth among internodes, leaves, and tendrils along single shoots was unaltered when growth was inhibited by water deficits. Growth of each organ was inhibited initially at soil water potential of -0.065 MPa and ceased completely at -0.54 MPa. Therefore, it was concluded that the sensitivity of growth to water deficits did not differ among shoot organs. The region along the shoot in which organs expanded was reduced during water deficits. Similarly, the regions within organs in which growth occurred diminished as water deficits developed. Although growth was inhibited in all tissues, inhibition was complete in older tissues when some growth was maintained in younger tissues. Therefore, it was concluded that sensitivity of growth to water deficits increased with ontogeny.

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.

NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS

1988 ◽  
Vol 68 (3) ◽  
pp. 569-576 ◽  
Author(s):  
YADVINDER SINGH ◽  
E. G. BEAUCHAMP
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Incubation Period ◽  
Relative Rate ◽  
Soil Water Potential ◽  
Nitrification Inhibitor ◽  
Silt Loam ◽  
Nitrogen Transformations ◽  
Water Potentials ◽  
Initial Soil

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

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