RELATIONSHIPS AMONG FREEZING, LOW TEMPERATURE FLOODING, AND ICE ENCASEMENT TOLERANCE IN ALFALFA

1990 ◽  
Vol 70 (1) ◽  
pp. 227-235 ◽  
Author(s):  
S. R. BOWLEY ◽  
B. D. McKERSIE
Keyword(s):  
Low Temperature ◽  
Environmental Stress ◽  
Stress Tolerance ◽  
Environmental Stresses ◽  
Freezing Stress ◽  
Yield Reduction ◽  
Ice Encasement ◽  
Medicago Sativa L ◽  
Selection For ◽  
The Relationship

In order to select cultivars with improved tolerance to environmental stresses, the relationship among tolerance to environmental stresses needs to be determined. This study evaluated 16 populations of alfafla for their tolerance to freezing (−8 to −16 °C), low temperature flooding (21 and 28 d), and ice encasement (10 and 14 d). Stresses were applied on field-grown plants excavated in November. Dry matter yield of the regrowth was determined 40 d following application of the stress. Two stands differing in plant ages (seeding year and first production year) over 2 yr were assessed. Seeding year plants were smaller in size, had fewer crown buds, lower moisture contents, and greater regrowth yields in the absence of stress. Regrowth yield was linearly related to stress level. Seeding year plants had greater absolute reductions in yield when subjected to freezing and icing stress, but less relative (to control) yield reduction when subjected to freezing stress compared to first production year plants. Plant age did not affect yield reduction of plants exposed to icing stress. Superiority index (Pi) ranking of the populations varied with environmental stress and was not correlated with moisture content, number of buds, or fall growth habit. Differential rankings of Pi among the freezing, flooding, and ice encasement stresses indicated that tolerance to one environmental stress will not necessarily give tolerance to other stresses. Selection for improved stress tolerance in alfalfa should be based on assessment of all stresses.Key words: Alfalfa, stress tolerance, environmental stress, Medicago sativa L.

SELECTION FOR SEED SET IN NONINBRED AND PARTLY INBRED POPULATIONS OF ALFALFA

1977 ◽  
Vol 57 (3) ◽  
pp. 873-881 ◽  
Author(s):  
R. MICHAUD ◽  
T. H. BUSBICE
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Exponential Model ◽  
Seed Setting ◽  
Medicago Sativa L ◽  
Selection For ◽  
Inbred Populations ◽  
The Relationship ◽  
Advanced Generation ◽  
Coefficient Of Inbreeding

Alfalfa (Medicago sativa L.) is a highly heterozygous cross-pollinating species, and most breeding efforts have been conducted on noninbred populations. The purpose of this study was to determine whether greater breeding progress could be made by selecting within partly inbred populations rather than within noninbred ones. One hundred and twenty F1 (noninbred) and 120 S1 (partly inbred) plants that were issued from crossing and selfing four alfalfa clones were evaluated for self-fertility. The most self-fertile 10% of the plants from each family were selected in each population. The selected plants within each level of inbreeding were intercrossed to produce an advanced generation in which the effectiveness of the selection was evaluated. Selection increased both self- and cross-fertility in the advanced generation. Selection was more effective at the F1 level than at the S1 level. Fertility was reduced drastically by inbreeding. The average self-fertility of the S1’s was only about 7% of the cross-fertility of their parental clones. An exponential model was proposed to describe the relationship between seed setting and the coefficient of inbreeding in the developing zygote. This model explained 95% of the variation among 11 unselected populations having differing levels of inbreeding.

scholarly journals Reduced interactivity during microbial community degradation lead to the extinction of Tricholomas matsutake

2021 ◽  
Author(s):  
Hanchang Zhou ◽  
Anzhou Ma ◽  
Liu Guohua ◽  
Xiaorong Zhou ◽  
Jun Yin ◽  
...  
Keyword(s):  
Microbial Community ◽  
Environmental Stress ◽  
Stress Tolerance ◽  
Soil Microbial Community ◽  
Species Conservation ◽  
Comprehensive Understanding ◽  
Community Interactions ◽  
Ecosystem Degradation ◽  
Soil Microbial ◽  
The Relationship

Ecosystem degradation is a process during which different ecosystem components interact and affect each other. The microbial community, as a component of the ecosystem whose members often display high reproduction rates, is more readily able to respond to environmental stress at the compositional and functional levels, thus potentially threatening other ecosystem components. However, very little research has been carried out on how microbial community degradation affects other ecosystem components, which hampers the comprehensive understanding of ecosystems as a whole. In this study, we investigated the variation in a soil microbial community through the extinction gradient of an ectomycorrhizal species (Tricholomas matsutake) and explored the relationship between microbial community degradation and ectomycorrhizal species extinction. The result showed that during degradation, the microbial community switched from an interactive state to a stress tolerance state, during which the interactivity of the microbial community decreased, and the reduced community interactions with T.matsutake marginalized it from a large central interactive module to a small peripheral module, eventually leading to its extinction. This study highlights the mechanisms of T.matsutake extinction due to the loss of soil microbial community interactivity, offering valuable information about soil microbial community degradation and the plant ectomycorrhizal species conservation.

METHODS FOR EVALUATING FROST HARDINESS IN ALFALFA

1975 ◽  
Vol 55 (3) ◽  
pp. 823-826 ◽  
Author(s):  
P. D. WALTON
Keyword(s):  
Low Temperature ◽  
Cell Count ◽  
Living Cell ◽  
Temperature Treatment ◽  
Regression Coefficients ◽  
Tissue Impedance ◽  
Low Temperature Treatment ◽  
Cell Counts ◽  
Medicago Sativa L ◽  
The Relationship

Root tissue excised from alfalfa cultivars (Medicago sativa L. and M. media Pers.) was used to determine relationships between impedance, living cell count and duration of low temperature treatment for cold-conditioned material. Correlations exist between all combinations of these three characters. For the cultivars studied, differences were found to exist between regression coefficients for the relationship between tissue impedance and living cell counts when tissue treated with sucrose was compared with tissue receiving no sucrose. The use of sucrose together with cold conditioning was also shown to be effective in detecting small differences in impedance between clones.

FALL GROWTH AND STAND PERSISTENCE OF ALFALFA IN INTERIOR BRITISH COLUMBIA

1985 ◽  
Vol 65 (4) ◽  
pp. 935-941 ◽  
Author(s):  
DARRYL G. STOUT
Keyword(s):  
British Columbia ◽  
North America ◽  
Low Temperature ◽  
Medicago Sativa ◽  
Winter Survival ◽  
Similar Relationship ◽  
Temperature Growth ◽  
Medicago Sativa L ◽  
The Relationship ◽  
Fall Growth

Stand persistence of eight alfalfa (Medicago sativa L.) cultivars in the Interior of British Columbia was correlated to fall growth. A similar relationship has been reported for alfalfa winter survival and fall growth in other parts of North America. One alfalfa cultivar, Anik, did not fit this relationship, since it had little fall growth and low stand persistence. Although the relationship between fall growth and stand persistence appears useful for predicting cultivar stand persistence, major exceptions can occur.Key words: Winter injury, Medicago sativa, low temperature growth

Gebirgswaldpflege – es kommt auf den Standort an | Mountain silviculture – it all depends on the site

2001 ◽  
Vol 152 (5) ◽  
pp. 169-176 ◽  
Author(s):  
Monika Frehner
Keyword(s):  
Nature Conservation ◽  
Low Temperature ◽  
Tree Species ◽  
Forest Stand ◽  
Ground Vegetation ◽  
Mountain Forests ◽  
Research Projects ◽  
Snow Mould ◽  
The Relationship ◽  
Protection Forests

The article shows that knowledge of the site of a particular forest stand, together with research results and experience, can provide information that is important for the cultivation of mountain forests, including knowledge of the composition of the tree species and the structure and growth capacity of natural forest. Furthermore, certain sites can, thus, be characterized by factors that influence restocking, such as snow mould,lush ground vegetation or low temperature. The guidelines«minimale Pflegemassnahmen» – «Minimal tending of protection forests» (WASSER und FREHNER, 1996) are based on this principle. For individual sites, warnings about natural dangers such as rock fall or statements concerning nature conservation can be made (e.g., the occurrence of tree species, suitability as a biotope for Capercaille). In conclusion, two research projects on the relationship between site and natural dangers will be presented.

Recurrent Selection for High Self‐Fertility in Vernal Alfalfa ( Medicago Sativa L.)

Crop Science ◽  
1971 ◽  
Vol 11 (6) ◽  
pp. 881-883 ◽  
Author(s):  
C. T. Villegas ◽  
C. P. Wilsie ◽  
K. J. Frey
Keyword(s):  
Medicago Sativa ◽  
Recurrent Selection ◽  
Medicago Sativa L ◽  
Selection For

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

Selection for Tolerance to Low Temperature‐Induced Spikelet Sterility at Anthesis in Rice 1

Crop Science ◽  
1986 ◽  
Vol 26 (4) ◽  
pp. 694-698 ◽  
Author(s):  
D. R. Khan ◽  
D. J. Mackill ◽  
B. S. Vergara
Keyword(s):  
Low Temperature ◽  
Spikelet Sterility ◽  
Selection For
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