Comparison of two air temperature based models for predicting phenophase occurrence in Persian lilacs (Syringa chinensis) cultivar Red Rothomagensis

1990 ◽  
Vol 68 (5) ◽  
pp. 1113-1116 ◽  
Author(s):  
Gary W. Moorman ◽  
James L. Rosenberger ◽  
Leslie A. Gladstone
Keyword(s):  
Mathematical Models ◽  
Key Words ◽  
Growth Model ◽  
Air Temperature ◽  
Growing Degree Days ◽  
Bud Break ◽  
Degree Days ◽  
Flower Bud ◽  
Phenological Data ◽  
Vegetative Bud

Phenological data collected for 9–11 years from genetically uniform Persian lilacs (Syringa chinensis L.) cultivar Red Rothomagensis were analyzed to determine whether the number of days elapsed between vegetative bud break and flower bud break is correlated with either the accumulated growing degree-days or the average daily temperature. The lack of statistically significant correlations between these variables suggests these mathematical models cannot accurately predict the onset of flower bud break for this cultivar. Key words: degree-days, growth model, phenology.

scholarly journals Growth and Development of Purple Nutsedge Based on Days or Thermal Units

2015 ◽  
Vol 33 (2) ◽  
pp. 165-173 ◽  
Author(s):  
R.S.O. Lima ◽  
E.C.R. Machado ◽  
A.P.P. Silva ◽  
B.S. Marques ◽  
M.F. Gonçalves ◽  
...  
Keyword(s):  
Plant Growth ◽  
Mathematical Models ◽  
Growth And Development ◽  
Dry Matter ◽  
Cyperus Rotundus ◽  
Growing Degree Days ◽  
Plant Growth And Development ◽  
Degree Days ◽  
Purple Nutsedge ◽  
Independent Trials

This work was carried out with the objective of elaborating mathematical models to predict growth and development of purple nutsedge (Cyperus rotundus) based on days or accumulated thermal units (growing degree days). Thus, two independent trials were developed, the first with a decreasing photoperiod (March to July) and the second with an increasing photoperiod (August to November). In each trial, ten assessments of plant growth and development were performed, quantifying total dry matter and the species phenology. After that, phenology was fit to first degree equations, considering individual trials or their grouping. In the same way, the total dry matter was fit to logistic-type models. In all regressions four temporal scales possibilities were assessed for the x axis: accumulated days or growing degree days (GDD) with base temperatures (Tb) of 10, 12 and 15 oC. For both photoperiod conditions, growth and development of purple nutsedge were adequately fit to prediction mathematical models based on accumulated thermal units, highlighting Tb = 12 oC. Considering GDD calculated with Tb = 12 oC, purple nutsedge phenology may be predicted by y = 0.113x, while species growth may be predicted by y = 37.678/(1+(x/509.353)-7.047).

scholarly journals Long-Term Trends in Air Temperature Distribution and Extremes, Growing Degree‐Days, and Spring and Fall Frosts for Climate Impact Assessments on Agricultural Practices in Nebraska

2012 ◽  
Vol 51 (11) ◽  
pp. 2060-2073 ◽  
Author(s):  
Kari E. Skaggs ◽  
Suat Irmak
Keyword(s):  
Air Temperature ◽  
Central City ◽  
Agricultural Practices ◽  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Temperature Changes ◽  
Growing Season Length ◽  
Average Maximum

AbstractAir temperature influences agricultural practices and production outcomes, making detailed quantifications of temperature changes necessary for potential positive and negative effects on agricultural management practices to be exploited or mitigated. Temperature trends of long-term data for five agricultural locations, ranging from the subhumid eastern to the semiarid western parts of Nebraska, were studied to determine local temperature changes and their potential effects on agricultural practices. The study quantified trends in annual and monthly average maximum and minimum air temperature (Tmax and Tmin), daily temperature range (DTR), total growing degree-days, extreme temperatures, growing‐season dates and lengths, and temperature distributions for five heavily agricultural areas of Nebraska: Alliance, Central City, Culbertson, Fremont, and Hastings. July and August were the months with the greatest decreases in Tmax for the central part of Nebraska—Culbertson, Hastings, and Central City. Alliance, Culbertson, and Fremont had year-round decreases in DTR. Central City and Hastings experienced growing‐season decreases in DTR. Increases in growing‐season length occurred at rates of 14.3, 16.7, and 11.9 days century−1 for Alliance, Central City, and Fremont, respectively. At Hastings, moderately earlier last spring frost (LS) at a rate of 6.6 days century−1 was offset by an earlier (2.7 days century−1) first fall frost (FF), resulting in only a 3.8 days century−1 longer growing season. There were only slight changes in LS and FF dates of around 2 days earlier and 1 day later per century, respectively, for Culbertson.

scholarly journals Fusarium root and crown rot in alfalfa subjected to autumn harvests

2002 ◽  
Vol 82 (3) ◽  
pp. 621-624 ◽  
Author(s):  
L. Couture ◽  
C. Dhont ◽  
F.-P. Chalifour ◽  
R. Drapeau ◽  
G. Tremblay ◽  
...  
Keyword(s):  
Key Words ◽  
Disease Severity ◽  
Crown Rot ◽  
Growing Degree Days ◽  
Harvest Management ◽  
Degree Days ◽  
Root And Crown Rot

Fusarium root and crown rot in alfalfa subjected to an autumn harvest was studied in plots established in the spring of 1996 or 1997, at three sites in Quebec. Autumn harvest treatments were started the year following establishment at each site. They were made at either 400, 500 or 600 growing degree-days (GDD; 5°C) after the last summer harvest. Samples were assessed for fusarium root and crown rot severity in autumn 1998 and spring 1999. Disease severity over all sites, cultivars, and sampling periods was ranked in the following order: 400 GDD > 500 GDD > 600 GDD > control (no fall harvest). Key words: Fusarium, root and crown rot, alfalfa, harvest management

scholarly journals Natural and Artificial Chilling of Southern Highbush Blueberry

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 825B-825
Author(s):  
Donna A. Marshall* ◽  
Stephen J. Stringer ◽  
James M. Spiers
Keyword(s):  
Bud Break ◽  
Delivery Method ◽  
Flower Bud ◽  
Bud Development ◽  
Chilling Requirements ◽  
Highbush Blueberries ◽  
Southern Highbush ◽  
Chilling Hours ◽  
Floral Bud ◽  
Vegetative Bud

A study was initiated in November, 2002 to determine the effects of exposing two Southern Highbush blueberries (Vaccinium corybosum L) to artificial chilling hours on initiation of bud break and advancement of floral and vegetative bud maturity. Plants of `Jubilee' and `Misty' were divided into 2 groups in which one was left outdoors, allowing chilling to occur and accumulate naturally, while the other group was placed in a growth chamber set at a constant artificial temperature of 4 °C. Five plants of each cultivar were then placed into a heated greenhouse after 0, 200, 400, 600, or 800 hours of chilling (total hours of exposure to <5 °C) had accumulated for forcing of flower bud development. The progression of floral bud development of the terminal three buds on five tagged stems was observed at 7-10 day intervals for 30 days. At the end of the forcing period observations were also made on total percent vegetative and floral bud break. Prior to accumulating sufficient chilling requirements, chilling delivery method did not appear to influence the rate of floral bud development since none advanced past stage 3 regardless of chilling regime used. However after chilling requirements were met, flower buds of plants that were allowed to chill naturally developed more quickly than did those chilled by artificial means.

Effects of thermal model and base temperature on estimates of thermal time to bud break in white spruce seedlings

2010 ◽  
Vol 40 (9) ◽  
pp. 1815-1820 ◽  
Author(s):  
Rongzhou Man ◽  
Pengxin Lu
Keyword(s):  
White Spruce ◽  
Climatic Conditions ◽  
Thermal Time ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Bud Break ◽  
Bud Burst ◽  
Degree Days ◽  
Growing Degree Hours ◽  
Time Requirements

To improve the predictability of bud burst and growth of boreal trees under varying climate, the thermal time for bud break in white spruce ( Picea glauca (Moench) Voss) seedlings was evaluated under a range of temperature conditions in controlled environment chambers. Thermal time requirements were calculated as the sum of growing degree days or growing degree hours above base temperatures ranging from –1 to 5 °C. The results indicated that the common modeling approach, which uses a high base temperature of 5 °C and growing degree days, may not be appropriate for future climatic conditions. Estimates of thermal time requirements using a base temperature of 5 °C varied considerably among temperature treatments and thus would reduce the predictability of bud burst under changing climate. In contrast, estimates of thermal time requirements with lower temperatures closer to 1 °C were relatively consistent among treatments. Growing degree hour models were less sensitive to base temperature than degree day models. These results should help in the selection of appropriate base temperatures and thermal time models in quantification of thermal time for bud burst modeling in other boreal trees.

Comparison of meadow fescue and meadow bromegrass in monoculture and in association with white clover

2009 ◽  
Vol 89 (6) ◽  
pp. 1059-1063 ◽  
Author(s):  
R Drapeau ◽  
G Bélanger
Keyword(s):  
Key Words ◽  
White Clover ◽  
Trifolium Repens ◽  
Grass Species ◽  
Growing Degree Days ◽  
Festuca Pratensis ◽  
Degree Days ◽  
Meadow Fescue ◽  
Bromus Riparius ◽  
Meadow Bromegrass

Meadow fescue and meadow bromegrass alone or with white clover were compared in a four cut system in a region with less than 1400 growing degree days. Cultivars of the two grass species did not affect yield. The annual yields of two grass species, alone or with white clover, were similar in the first production year, but in second and third production years, meadow bromegrass yielded more than meadow fescue. The persistence of white clover, alone or with a grass, was limited. Key words: Festuca pratensis, Bromus riparius, Trifolium repens, yield

THE DETERMINATION AND VERIFICATION OF A BASELINE TEMPERATURE FOR THE GROWTH OF WESTAR SUMMER RAPE

1989 ◽  
Vol 69 (2) ◽  
pp. 455-464 ◽  
Author(s):  
M. J. MORRISON ◽  
P. B. E. McVETTY ◽  
C. F. SHAYKEWICH
Keyword(s):  
Temperature Field ◽  
Brassica Napus ◽  
Controlled Environment ◽  
Growing Degree Days ◽  
Degree Days ◽  
Brassica Napus L ◽  
Physiological Maturity ◽  
Phenological Data ◽  
Whole Plant ◽  
Baseline Temperature

Controlled environment growth cabinets set at mean temperatures of 10, 13.5, 15, 17, 20, 22 and 25 °C were used to determine a baseline temperature of 5 °C for the growth of Westar summer rape (Brassica napus L.). Temperatures in excess of 25 °C caused whole plant sterility. Phenological data obtained from ten field sites, collected over three years, was used to verify the 5 °C baseline temperature. Field growing degree days (GDD) and cabinet GDD were not significantly different. The percent development to physiological maturity (% DPM) of field grown Westar summer rape, as influenced by temperature, was not significantly different from that predicted by the cabinet determined equation. The agreement between field and cabinet GDD and observed and predicted % DPM verified the use of a 5 °C baseline temperature in field GDD equations. % DPM and GDD were found to be better estimators of phenological development in the field than calendar days. A simple linear model, relating % DPM to GDD was developed. It was concluded that temperature is the most important environmental factor regulating the phenological development of Westar summer rape in western Canada.Key words: Westar summer rape, Brassica napus, baseline temperature, phenological development, growing degree days

Evaluation of Finger Millet Varieties under Rainfed Condition of Eastern India

2017 ◽  
Vol 4 (03) ◽  
Author(s):  
M. K. Singh ◽  
VINOD KUMAR ◽  
SHAMBHU PRASAD
Keyword(s):  
Field Experiment ◽  
Finger Millet ◽  
Yield Potential ◽  
Growing Degree Days ◽  
Eastern India ◽  
Degree Days ◽  
Rainfed Condition ◽  
Net Returns ◽  
Humid Environment ◽  
Use Efficiency

A field experiment was carried out during the kharif of 2014 and 2015 to evaluate the yield potential, economics and thermal utilization in eleven finger millet varieties under the rainfed condition of the sub-humid environment of South Bihar of Eastern India. Results revealed that the significantly higher grain yield (20.41 q ha-1), net returns (Rs 25301) and B: C ratio (1.51) was with the finger millet variety ‘GPU 67’ but was being at par to ‘GPU28’and ‘RAU-8’, and significantly superior over remaining varieties. The highest heat units (1535.1oC day), helio-thermal units (7519.7oC day hours), phenothermal index (19.4 oC days day-1) were recorded with variety ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ and lowest in ‘VL 149’ at 50 % anthesis stage. Similarly, the highest growing degree days (2100 oC day), helio-thermal units (11035.8 oC day hours) were noted with ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ at maturity. The highest heat use efficiency (0.97 kg ha-1 oC day) and helio-thermal use efficiency (0.19 kg ha-1 oC day hour) were in ‘GPU 67’ followed by ‘VL 315’.

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