Comparison of the effects of the physical and chemical components of soil water energy on seed germination

1962 ◽  
Vol 13 (4) ◽  
pp. 575 ◽  
Author(s):  
N Collis-George ◽  
JE Sands
Keyword(s):  
Free Energy ◽  
Soil Moisture ◽  
Seed Germination ◽  
Osmotic Potential ◽  
Chemical Components ◽  
Matric Potential ◽  
Experimental Procedure ◽  
Germination Behaviour ◽  
Physical And Chemical ◽  
Osmotic Potentials

The components of total soil moisture energy of consequence to a biological system are matric potential and osmotic potential. An experimental procedure, which allows the effects of the potentials to be considered independently, is described and discussed. Germination behaviour does not support the hypothesis that matric and osmotic potentials should have similar biological consequences because their free energy measurements are identical. The results support a diffusion phenomenon hypothesis with movement of solute from the soil solution through the cell membranes, so that any biological consequence is that of an internal "toxicity" rather than an osmotic "drought". For some osmotic systems, 100 cm of matric potential is as effective as 10 000 cm of osmotic potential in retarding seed germination rates.

scholarly journals Effect of Osmotic and Matric Potentials on the Availability of Water for Seed Germination

1971 ◽  
Vol 24 (3) ◽  
pp. 423 ◽  
Author(s):  
JR Mcwilliam ◽  
PJ Phlllips
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Osmotic Stress ◽  
Soil Water ◽  
Seed Coat ◽  
Moisture Diffusivity ◽  
Matric Potential ◽  
Water Potentials ◽  
Germination Behaviour ◽  
Dry Soil

Under special conditions where soil-moisture diffusivity and seed-soil contact are non-limiting, the osmotic and matric potentials of the substrate were found to be equivalent in their effect on the germination of seeds of ryegrass and dehulled phalaris over a range of water potentials from 0 to -15 bars. However, with intact phalaris seeds it appears that the seed coat constitutes a large resistance to the absorption of soil water, and under these conditions the equivalence between osmotic and matric potential no longer holds, and results of germination under osmotic stress must be used with caution in predicting the germination behaviour of seeds in dry soil.

Comparison of the effects of soil matric potential and isotropic effective stress on the germination of Lactuca sativa

Soil Research ◽  
1968 ◽  
Vol 6 (2) ◽  
pp. 179 ◽  
Author(s):  
N Collis-George ◽  
J Williams
Keyword(s):  
Free Energy ◽  
Seed Germination ◽  
Soil Water ◽  
Effective Stress ◽  
Lactuca Sativa ◽  
Soil Matric Potential ◽  
Matric Potential ◽  
Soil System

The matric potential contributes positively to the isotropic effective stress operating in the solid framework of a soil system. Collis-George and Hector (1966) suggested that the matric potential may influence seed germination through its contribution to the effective stress in the solid framework surrounding the seed. Experiments are described which separate the effects of matric potential on seed germination into those that can be attributed to the free energy of the soil water and those that can be attributed to the effective stress in the soil system. The results clearly indicate that (1) seed germination is influenced by the isotropic effective stress in the solid framework of the soil system, and (2) the influence of matric potential on seed germination in the range 0 to - 400cm of water can be wholly attributed to the isotropic effective stress in the solid framework and not to the free energy of the soil water as defined by the matric potential. These conclusions are discussed in terms of the behaviour of other organisms in response to an applied matric potential.

Germination of seeds as influenced by matric potential and by area of contact between seed and soil water

Soil Research ◽  
1966 ◽  
Vol 4 (2) ◽  
pp. 145 ◽  
Author(s):  
N Collis-George ◽  
JB Hector
Keyword(s):  
Seed Germination ◽  
Soil Water ◽  
Lactuca Sativa ◽  
Contact Area ◽  
Germination Rate ◽  
Free Water ◽  
Matric Potential ◽  
Germination Behaviour ◽  
Wetted Area ◽  
Design Experiments

Experiments with Medicago tribuloides and Lactuca sativa confirm Sedgley's conclusion that the wetted area of contact is a factor controlling germination of the seed. The evidence suggests that this is of consequence at matric potentials near that of free water and is most important for germination of the last seeds in each population. Matric potential is shown to be an important factor in seed germination over and above its effect in controlling the wetted contact area of seed and medium. Prewetting the seed at matric potentials near that of free water for a few minutes increases the germination rate markedly and minimizes the normal effect of matric potential. The results and experimental conclusions are discussed and are shown to indicate the need for further investigation. They show that it is practicable to design experiments to distinguish the effects of the various facets of soil water energy on seed germination behaviour.

scholarly journals Seed Germination of Four Lupine Species under Differing Osmotic Condition

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 476D-476
Author(s):  
Wayne A. Mackay ◽  
Tim D. Davis
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
The Other ◽  
West Texas ◽  
Desert Species ◽  
Petri Dishes ◽  
Peg 8000 ◽  
Osmotic Potentials

Seeds of four lupine species (L. microcarpus var. aureus, L. havardii, L. succulentis, and L. texensis) were subjected to 0, –2, –4, –6, or –8 bars osmotic potential using PEG 8000 solutions. Seeds of all species were acid scarified prior to placement in petri dishes containing the osmotic solutions. Petri dishes were placed in a seed germination chamber at 25°C with germination data collected daily for 15 days. Seeds of L. havardii, a desert species native to west Texas exhibited the greatest germination as osmotic potential declined while L. succulentis, a species adapted to moist sites, exhibited the greatest decline in germination as osmotic potential decreased. The other species exhibited intermediate germinability under the lower osmotic potentials.

scholarly journals Seed Germination and Initial Growth of Quinoa Seedlings Under Water and Salt Stress

2019 ◽  
Vol 11 (15) ◽  
pp. 153 ◽  
Author(s):  
Geovana Facco Barbieri ◽  
Raquel Stefanello ◽  
Janine Farias Menegaes ◽  
Janete Denardi Munareto ◽  
Ubirajara Russi Nunes
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Chenopodium Quinoa ◽  
Dry Mass ◽  
Germination Percentage ◽  
Initial Growth ◽  
Peg 6000 ◽  
Germination Process ◽  
Seedling Length ◽  
Osmotic Potentials

Excessive amounts of salts and soil water deficiency interfere on seed germination and the full development of several crops. The objective of this research was to evaluate the effect of water stress and salinity on the germination process and initial growth of quinoa (Chenopodium quinoa Willd.) seedlings. In the first experiment, two quinoa seed lots with different physiological conditions were distributed on paper soaked in aqueous solution containing polyethylene glycol PEG-6000 in osmotic potentials corresponding to 0.0; -0.1; -0.2; -0.3 and -0.4 MPa and held at 20 °C under 8 hours of light exposition. In the second experiment, solutions of sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2) and magnesium chloride (MgCl2) were used to simulate the effect of salinity using the osmotic potentials, temperature and light conditions previously described. Assessed parameters were the germination percentage, first count, length and dry mass of seedlings. There was a reduction in quinoa germination percentage, first seed count and seedling length as the osmotic potential decreased in CaCl2, NaCl, KCl, MgCl2 and PEG-6000 solutions. The quinoa seeds exhibited higher tolerance to NaCl and KCl salts in the germination process and initial seedling growth. The progressive reduction of the osmotic potential induced by salts NaCl, KCl, CaCl2, MgCl2 and PEG-6000 negatively affects seed germination and initial growth of quinoa seedlings.

Germination, Emergence, and Seedling Establishment of Buffalo Gourd (Cucurbita foetidissima)

Weed Science ◽  
1994 ◽  
Vol 42 (3) ◽  
pp. 358-363 ◽  
Author(s):  
Michael J. Horak ◽  
Jonathan K. Sweat
Keyword(s):  
Seed Germination ◽  
Seedling Establishment ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Buffalo Gourd ◽  
Osmotic Potentials

Studies were conducted to determine the effects of scarification, temperature, osmotic potential, and pH on seed germination of buffalo gourd and to examine seedling emergence and establishment. Mechanical and chemical scarification did not increase germination compared to non-scarified seed. Seed germinated at constant temperatures in the dark from 15 to 37 C with optimum germination at 25 C. As osmotic potentials became more negative from −0.1 to −0.8 MPa, germination decreased from 77 to 53%. Germination increased from 15% at pH 2.2 to 90% at pH 8. Seedlings were able to emerge from depths as great as 12 cm, and plants younger than 19 d were not able to sprout from the roots when the shoots were removed.

scholarly journals Mobilization of reserves and germination of seeds of Erythrina velutina Willd. (Leguminosae - Papilionoideae) under different osmotic potentials

2012 ◽  
Vol 34 (4) ◽  
pp. 580-588 ◽  
Author(s):  
Renata Conduru Ribeiro Reis ◽  
Bárbara França Dantas ◽  
Claudinéia Regina Pelacani
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Germination Percentage ◽  
Uniformity Coefficient ◽  
Carbon And Nitrogen ◽  
Germination Process ◽  
Mean Time ◽  
Osmotic Potentials

Some environmental factors, including water availability, may influence seed germination. This study investigated the germination of E. velutina seeds submitted to different osmotic potentials and mobilization of reserves during water-stress. Scarified seeds were arranged in paper rolls and soaked in solutions of Polyethylene Glycol (PEG) prepared in osmotic potentials 0.0, -0.2, -0.4, -0.6, and -0.8 MPa and kept into a seed germinator, at 25 °C, and 12/12 h photoperiod (L/D), during 10 days. The percentage, mean time, mean speed, germination speed index; as well as the germination uniformity coefficient were assessed. During germination process the total soluble sugars, reducing sugars, soluble protein, and total amino acids were quantified in the cotyledon, hypocotyl and radicle of soaked seeds and cotyledons of quiescent seeds (control). There was influence of osmotic potential on E. velutina seed germination. The germination percentage remained at high levels until -0.6 MPa and above this osmotic potential there has been no germination. The mobilization of stored reserves of carbon and nitrogen in E. velutina seeds was also influenced by water-stress. There was sensitiveness between -0.2 and -0.6 MPa; however, the degradation and the mobilization of reserves was slower when the osmotic potential decreased.

Influence of soil moisture regime on the respiration response of soils subjected to osmotic stress

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 161 ◽  
Author(s):  
GP Sparling ◽  
AW West ◽  
J Reynolds
Keyword(s):  
Soil Moisture ◽  
Microbial Biomass ◽  
Osmotic Stress ◽  
Respiration Rate ◽  
Osmotic Potential ◽  
Moisture Regime ◽  
Air Drying ◽  
Climatic Regions ◽  
Soil Moisture Regime ◽  
Osmotic Potentials

The influence of the soil moisture regime on the tolerance of the soil micro-organisms to increased osmotic stress was examined by laboratory tests with a range of New Zealand soils. Soils from various climatic regions (moist, intermediate and dry) were amended with glucose-NaCl solutions, incubated for 0.5 h, and the respiration rate over the following 2 h was used as a measure of the response of the microbial biomass to the changed osmotic potential. Osmotic potentials were varied between -4 and -80 bar by altering the concentration of NaCl. Air-drying the soils at 25�C decreased the respiration response of the microbial biomass by 3-60% but had little effect on the tolerance of the surviving populations to decreased osmotic potentials. In general, the soils showed the same patterns: an osmotic potential of -23 bar decreased the respiration response by 28-45% (18-44% after air-drying) and a -80 bar potential decreased it by 64-86% (52-84% after air-drying). For the majority of soils, a consistent relationship was obtained between the respiration rate of the moist soils and the osmotic potential applied. A reasonable prediction of the respiration response after air-drying could be obtained from the respiration response of moist soils at -25 bar osmotic potential.

Effects of Light, Temperature and Osmotic Stress on Seed Germination of Eucalyptus occidentalis Endl

1975 ◽  
Vol 23 (3) ◽  
pp. 391 ◽  
Author(s):  
Y Zohar ◽  
Y Waisel ◽  
R Karschon
Keyword(s):  
Seed Germination ◽  
Osmotic Stress ◽  
Osmotic Potential ◽  
Continuous Light ◽  
Decisive Factor ◽  
Temperature Optimum ◽  
Dark Stress ◽  
Osmotic Potentials ◽  
Eucalyptus Occidentalis ◽  
Effect Of Light

Seed germination of E. occidentalis was examined under different combinations of light, temperature and osmotic potential. The effects of all three factors were found to be interrelated. Germination rates are directly related to the temperature of the environment between 15 and 30�C and to the osmotic potentials of the medium between -9.1 and 0 bars. The relative require- ment for light, i.e. the ratio of light germination to dark germination, increases with the rise in temperature. Light is a decisive factor in improving germination under osmotic stress; its effect is directly related to the intensity of stress. In media with an osmotic potential of -9.1 bars, the effect of light on germination is directly related to temperature. Optimum germination occurs at 30" under continuous light and under no osmotic styes. Very low germination is obtained under the same temperature in the absence of light and in a medium with an osmotic potential of -9.1 bars. Inhibition of germination caused by osmotic stress is 2-3 times as great as that caused by dark stress. Seed germination was found to vary according to an annual rhythm. Lower rates of germination were obtained in July and January, whereas maximum germination occurred from March to May.

scholarly journals Influence of pH and Matric Potential on Germination of Cephalosporium gramineum Conidia

Plant Disease ◽  
1998 ◽  
Vol 82 (9) ◽  
pp. 975-978 ◽  
Author(s):  
Cynthia A. Blank ◽  
Timothy D. Murray
Keyword(s):  
Soil Moisture ◽  
Soil Ph ◽  
Significant Influence ◽  
Phosphate Buffer ◽  
Mineral Salts ◽  
Matric Potential ◽  
High Soil Moisture ◽  
Soil Fungistasis ◽  
Cephalosporium Gramineum ◽  
Influence Of Ph

Germination of Cephalosporium gramineum conidia in soil was up to twofold greater at -0.064 MPa than at -0.037 and -0.007 MPa when incubated at 5°C for 2 days. Soil pH from 4.7 to 7.5 did not have a significant influence on germination of conidia and the interaction between soil pH and matric potential on germination was not significant. Soil fungistasis, which was previously observed for conidia of C. gramineum, was not observed in these studies. Germination of conidia on mineral salts agar containing phosphate buffer was significantly less at pH 4.5 than at 5.5, 6.5, or 7.5 at 5°C in one of two experiments; however, pH had no influence on germination at 10 or 20°C in two experiments. Although Cephalosporium stripe is more severe under conditions of high soil moisture and low soil pH, increased germination of conidia in response to these factors does not explain the observed increase in disease.

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