scholarly journals A comparison of cumulative-germination response of cheatgrass (Bromus tectorum L.) and five perennial bunchgrass species to simulated field-temperature regimes

2010 ◽  
Vol 69 (3) ◽  
pp. 320-327 ◽  
Author(s):  
Stuart P. Hardegree ◽  
Corey A. Moffet ◽  
Bruce A. Roundy ◽  
Thomas A. Jones ◽  
Stephen J. Novak ◽  
...  
Keyword(s):  
Bromus Tectorum ◽  
Germination Response ◽  
Temperature Regimes ◽  
Field Temperature ◽  
Simulated Field

Population, Temperature, and Substrate Influences on Common Milkweed (Asclepias syriaca) Seed Germination

Weed Science ◽  
1986 ◽  
Vol 34 (4) ◽  
pp. 525-528 ◽  
Author(s):  
Janis M. Farmer ◽  
Steven C. Price ◽  
C. Ritchie Bell
Keyword(s):  
Geographical Origin ◽  
Source Population ◽  
Strongly Correlated ◽  
Substrate Type ◽  
Asclepias Syriaca ◽  
Experimental Conditions ◽  
Germination Response ◽  
Temperature Regimes ◽  
Percent Germination ◽  
Different Populations

Seed from 21 common milkweed (Asclepias syriacaL. # ASCSY) populations from six states were germinated on six substrates (filter paper, sand, peat, clay, and mixtures) under three temperature regimes. The variation in germination response between populations and experimental conditions was analyzed. The greatest percent germination (59% average over all substrates) was obtained with an alternating 20 C (16 h), 30 C (8 h) temperature regime. At a constant temperature of 30 C, germination was lower (32% average) and much more variable among seeds from different populations. At 25 C, average percent germination dropped to 1.2% over all substrates. Germination appeared to be strongly correlated with seed source (population), temperature, and substrate type, and poorly correlated with seed size. No association was found between geographical origin and germination response.

scholarly journals Germination response to various temperature regimes of four Mediterranean seeder shrubs across a range of altitudes

Plant Ecology ◽  
2013 ◽  
Vol 214 (12) ◽  
pp. 1431-1441 ◽  
Author(s):  
Daniel Chamorro ◽  
Belén Luna ◽  
José M. Moreno
Keyword(s):  
Germination Response ◽  
Temperature Regimes

Effect of temperature on the development of two annual medics

1979 ◽  
Vol 30 (5) ◽  
pp. 909 ◽  
Author(s):  
NM Clarkson ◽  
JS Russell
Keyword(s):  
Temperature Data ◽  
Effect Of Temperature ◽  
Night Temperature ◽  
Daily Minimum ◽  
Daily Increments ◽  
Temperature Regimes ◽  
Medicago Scutellata ◽  
Field Temperature ◽  
Annual Medics

Development of two annual medics (Medicago scutellata cv. Robinson and M. truncatula cv. Jemalong) was recorded under four controlled day/night temperature regimes of 12/5°, 18/11°, 24/17° and 30/23°C. Equations expressing the fractional daily increments of development as a function of daily mean temperatures were derived from the results. From these equations and field temperature data, predictions of development in the field were compared with observations from 24 serial monthly plantings at Warwick in southern Queensland. Predictions were satisfactory for all stages from planting to first mature pod for cv. Robinson and for all stages except flowering for cv. Jemalong. Inclusion of a vernalization constraint with daily minimum temperatures improved the prediction of flowering, but unknown factors delayed this stage in plantings of cv. Jemalong from January to April.

Bromus tectorum seed germination: between-population and between-year variation

1996 ◽  
Vol 74 (6) ◽  
pp. 875-882 ◽  
Author(s):  
Julie Beckstead ◽  
Susan E. Meyer ◽  
Phil S. Allen
Keyword(s):  
Seed Germination ◽  
Bromus Tectorum ◽  
Incubation Temperature ◽  
Weather Conditions ◽  
Germination Percentage ◽  
Maximum Temperature ◽  
Germination Time ◽  
Germination Response ◽  
Mean Germination Time ◽  
Contrasting Habitats

Cheatgrass (Bromus tectorum L., Poaceae), an introduced winter annual, has invaded a variety of habitats in western North America. This study examines variation in cheatgrass germination response and after-ripening patterns that are related to differences in habitat and to yearly differences in weather conditions during seed maturation. Seeds collected from five contrasting populations in 1992 and 1993 were subjected to controlled dry storage and then incubated across a range of temperatures. Recently harvested seeds were dormant and germinated slowly, while fully after-ripened seeds were nondormant and germinated rapidly. The optimal incubation temperature for mean germination time shifted from 5:15 to 20:30 °C as a result of after-ripening. Between-population differences in germination response appear to be related to the potential risk of precocious summer germination. The results from this 2-year study suggest that the more extreme yet predictable environments select for seed germination and after-ripening patterns that are genetically fixed, while populations from more favorable environments tended to show more between-year variations, suggesting more phenotypic plasticity. Germination percentage showed greater between-year variation than mean germination time. Between-year differences could not be explained simply by differences in maximum temperature or total precipitation during maturation. Adaptive germination responses in cheatgrass populations from contrasting habitats may have both genetic and environmental components, thus explaining why this species can become established in such a variety of habitats. Keywords: after-ripening, invading species, dormancy, mean germination time, cheatgrass, downy brome.

scholarly journals Effect of Variable Temperature on Infection Severity of Podosphaera macularis on Hops

2003 ◽  
Vol 93 (12) ◽  
pp. 1587-1592 ◽  
Author(s):  
Walter F. Mahaffee ◽  
William W. Turechek ◽  
Cynthia M. Ocamb
Keyword(s):  
Disease Risk ◽  
Variable Temperature ◽  
Optimal Conditions ◽  
Risk Assessment Models ◽  
Temperature Regimes ◽  
Uninoculated Control ◽  
Growth Chambers ◽  
Simulated Field ◽  
Favorable Conditions ◽  
Podosphaera Macularis

The effect of variable temperature on the infection severity of Podosphaera macularis was investigated. Potted ‘Symphony’ hop plants were inoculated and exposed to different temperature regimes that included supraconducive temperatures (30 to 42°C) for varying periods of time (2 to 9 h). Infection severity (lesions per cm2 of leaf area) was calculated 7 to 10 days after inoculation. Immediately exposing inoculated plants to 30°C for as little as 2 h significantly (P ≤ 0.05) reduced infection severity compared with exposure at a constant 18°C. However, exposure of inoculated plants to optimal conditions for 24 or 48 h prior to exposure to supraconducive conditions reduced this effect for plants exposed to 30, 33, or 36°C. Exposure to 39 or 42°C for 2 or more hours resulted in infection frequencies not significantly different from that of the uninoculated control regardless of prior exposure to favorable conditions. Exposure to simulated field temperatures programmed into growth chambers indicated that inoculation at 1700 or 2100 h resulted in significantly more disease than did inoculation at 0900 or 1300 h. Plants exposed to supraconducive or simulated field temperatures for 7 days prior to inoculation developed significantly lower disease severity than did plants maintained at 18°C for 7 days. The magnitude, length, and time of exposure to supraconducive temperatures in relation to time of inoculation plays an important role in the development of hop powdery mildew, and rules addressing these variables could be a useful addition to disease risk assessment models.

Effects of Simulated Field Temperatures and Chilling on Itchgrass (Rottboellia exaltata), Corn (Zea mays), and Soybean (Glycine max)

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 645-650 ◽  
Author(s):  
D. T. Patterson ◽  
E. P. Flint
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Leaf Area ◽  
Dry Matter ◽  
Baton Rouge ◽  
Gulf Coast ◽  
Dry Weight ◽  
Temperature Regimes ◽  
Net Assimilation ◽  
Simulated Field

Mathematical growth analysis techniques were used to study the effects of simulated field temperatures and chilling events on the growth of the exotic noxious weed itchgrass (Rottboellia exaltataL. f.) and adapted varieties of corn (Zea maysL. ‘DeKalb XL43’ and ‘DeKalb XL395′), and soybean [Glycine max(L.) Merr. ‘Corsoy’, ‘Williams', and ‘Tracy’] in climate-controlled greenhouses and growth chambers. Itchgrass grew vigorously and produced seed in temperature regimes simulating the warmest 4 months of the growing season in the Gulf Coast states (30/25 C, day/night), the central Midwest (27/21 C), and the northern Midwest (23/18 C). At 30/25 C day/night, itchgrass produced 707 g of dry matter and 1907 seed per plant after 119 days. Itchgrass produced 621 g dry matter and 1429 seed at 27/21 C and 499 g dry matter and 1160 seed at 23/18 C. Itchgrass and adapted varieties of corn and/or soybeans were grown in four additional temperature regimes simulating the first 5 weeks of the growing seasons for corn and soybean at Madison, Wisconsin (19/11 C day/night); for soybean at Carbondale, Illinois (24/20 C); for corn at Waycross, Georgia (20/14 C); and for soybean at Baton Rouge, Louisiana (27/23 C). After 24 days of growth, half the plants in each regime were exposed to 3 days of chilling (11/4 C for Madison, 17/10 C for Carbondale, 15/6 C for Waycross, and 24/18 C for Baton Rouge) and returned to the original growth regimes for recovery. The chilling treatments reduced dry matter production, net assimilation rate, and leaf area duration more in itchgrass than in corn or soybean. After recovery, the previously chilled itchgrass plants had greater reductions in height, leaf area, and dry weight, compared to unchilled controls, than did corn or soybean. Weed/crop ratios in height, leaf area, and dry weight for itchgrass/corn were significantly reduced by chilling. In the two cooler regimes, weed/crop ratios in leaf area and dry weight for itchgrass/soybean were significantly reduced by chilling. Because of its sensitivity to cool temperatures, itchgrass, is unlikely to be an important early-season competitor with corn or with soybean outside the South.

Germination of Dandelion Seed on a Thermogradient Plate

Weed Science ◽  
1974 ◽  
Vol 22 (5) ◽  
pp. 506-507 ◽  
Author(s):  
P. R. Mezynski ◽  
D. F. Cole
Keyword(s):  
Taraxacum Officinale ◽  
Fresh Seed ◽  
Germination Response ◽  
Temperature Regimes ◽  
Wide Range ◽  
Alternating Temperature ◽  
Germination Requirement

Fresh and stored dandelion (Taraxacum officinale Weber) seeds were studied to determine the germination response to a range of constant and alternating temperature regimes on thermogradient plates. Germination was initiated over a wide range of temperatures. Maximum germination of fresh seed occurred at an alternating temperature of 20 C for 16 hr and 10 C for 8 hr. Seed stored for 30 days germinated best at 20 C for 16 hr and 15 C for 8 hr. In addition to the shift in germination requirement, dormancy increased during the 30-day storage, especially at −15 C.

The development of milky disease under laboratory and field temperature regimes

1980 ◽  
Vol 36 (2) ◽  
pp. 203-210 ◽  
Author(s):  
R.J. Milner ◽  
J.T. Wood ◽  
E.R. Williams
Keyword(s):  
Temperature Regimes ◽  
Field Temperature
Sign in / Sign up

Export Citation Format

Share Document