scholarly journals A Heat Unit Model to Predict Growth and Development of Muskmelon (Cucumis melo var. reticulatus Naud.) to Anthesis

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 790D-790
Author(s):  
S. Jenni ◽  
D.C. Cloutier ◽  
G. Bourgeois ◽  
K.A. Stewart
Keyword(s):  
Cucumis Melo ◽  
Dry Weight ◽  
Base Temperature ◽  
Degree Days ◽  
Heat Unit ◽  
Air Temperatures ◽  
Unit Model ◽  
Dependent Variables ◽  
Soil Temperatures ◽  
Unit Formula

Plant dry weight of muskmelon transplants to anthesis could be predicted from a multiple linear regression based on air and soil temperatures prevailing under 11 mulch and rowcover combinations. The two dependent variables of the regression model consisted of a heat unit formula for air temperatures with a base temperature of 14C and a maximum-reduced threshold at 40C, and a standard growing-degree-day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5% of the variation in the dry weight (on a log scale) could be predicted with this model. The base temperature for predicting time to anthesis of muskmelon transplants was established at 6.8C and the thermal time ranged between 335 and 391 degree-days during the 2 years of the experiment.

scholarly journals A Heat Unit Model to Predict Growth and Development of Muskmelon to Anthesis of Perfect Flowers

1996 ◽  
Vol 121 (2) ◽  
pp. 274-280 ◽  
Author(s):  
Sylvie Jenni ◽  
Daniel C. Cloutier ◽  
Gaétan Bourgeois ◽  
Katrine A. Stewart
Keyword(s):  
Cucumis Melo ◽  
Dry Weight ◽  
Developmental Time ◽  
Base Temperature ◽  
Heat Unit ◽  
Independent Variables ◽  
Air Temperatures ◽  
Unit Model ◽  
Soil Temperatures ◽  
Unit Formula

Growth of `Earligold' muskmelon (Cucumis melo L.), expressed as plant dry weight from transplanting to anthesis, could be predicted using a multiple linear regression based on air and soil temperatures for 11 mulch and rowcover combinations. The two independent variables of the regression model consisted of a heat unit formula for air temperatures, with a base temperature of 14C and a maximum reduced threshold of 40C, and a standard growing-degree day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5% of the variation in the dry weight (on a log scale) could be predicted with this model. The base temperature for predicting developmental time to anthesis of perfect flowers was established at 6.8C and the thermal time ranged between 335 and 391 degree days in the 2 years of the experiment.

scholarly journals Use of Belowground Growing Degree Days to Predict Rooting of Dormant Hardwood Cuttings of Populus

2004 ◽  
Vol 53 (1-6) ◽  
pp. 154-160 ◽  
Author(s):  
R. S. Zalesny ◽  
E. O. Bauer ◽  
D. E. Riemenschneider
Keyword(s):  
Populus Deltoides ◽  
Dry Weight ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Planting Dates ◽  
Growing Period ◽  
Period 2 ◽  
Soil Temperatures ◽  
Total Dry Weight

Abstract Planting Populus cuttings based on calendar days neglects soil temperature extremes and does not promote rooting based on specific genotypes. Our objectives were to: 1) test the biological efficacy of a thermal index based on belowground growing degree days (GDD) across the growing period, 2) test for interactions between belowground GDD and clones, and 3) identify beneficial planting windows based on combinations of genotypes and belowground GDD. We tested two clones of Populus deltoides Bartr. ex Marsh (D133, D134) and four hybrid clones of P. deltoides × P. maximowiczii A. Henry (DM101, DM105, NC14105, NC14107). Cuttings, 20 cm long, were planted in randomized complete blocks at 15- × 15-cm spacing across three planting dates during 1999 at Alexandria, Minnesota, USA (45.9°N, 95.4°W) and Fertile, Minnesota, USA (47.3°N, 96.2°W). Temperatures at 20 cm belowground were converted to GDD with a base temperature of 10°C. We measured root, top, and total dry weight, along with number of roots after 14 d of growth. Relatively warmer and cooler soil temperatures promoted rooting for the cottonwoods and hybrids, respectively. We recommend planting after reaching a threshold of 163 belowground GDD for P. deltoides clones and planting before reaching a threshold of 173 belowground GDD for P. deltoides × P. maximowiczii clones.

scholarly journals Influence of Various Polyethylene Mulch Colors on Growth and Development of `Vates' Collards

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 600D-600
Author(s):  
J.M Kemble ◽  
J. Brown ◽  
E. Simonne
Keyword(s):  
Growth And Development ◽  
Soil Depth ◽  
Dry Weight ◽  
Base Temperature ◽  
Fresh Weight ◽  
Degree Days ◽  
Marketable Yield ◽  
Soil Temperatures ◽  
Polyethylene Mulch ◽  
Final Harvest

The effect of various mulch colors (black, yellow, red, blue, white, and aluminum) on growth and development of `Vates' collards was evaluated in Fall 1996 at the E.V. Smith Research Center in Shorter, Ala. Black polyethylene mulch was installed onto raised, fumigated beds, then sprayed with a 1: 2 (v/v) mixture of exterior oil-based enamel paint to paint thinner with one of the five mulch colors listed. Five-week-old plants were transplanted into beds. Beginning two weeks after transplanting and continuing every other week thereafter, heads were harvested to determine head fresh weight and dry weight. Hourly soil temperatures at 10 cm soil depth were recorded and growing degree days (GDDs) with a base temperature of 4.4 °C were calculated. At two weeks after transplanting, average head fresh and dry weight were highest for the aluminum-colored treatment with head fresh (24.7 and 12.3 g, respectively) and dry weights (2.7 and 1.3 g, respectively) twice that of the yellow treatment (P ≤ 0.05). By four weeks after transplanting and up through the final harvest, marketable yield and average head fresh weights did not differ among the treatments (17,900 kg/ha, 1.4 kg per head, respectively). The red and black mulch treatments accumulated more GDDs than the other treatments, but total marketable yields did not differ among any treatments.

scholarly journals Spatial Soil Temperature and Moisture Monitoring Across the Transylvanian Plain in Romania

2010 ◽  
Vol 67 (1) ◽  
Author(s):  
Beatrix HAGGARD ◽  
Teodor RUSU ◽  
David WEINDORF ◽  
Horea CACOVEAN ◽  
Paula MORARU ◽  
...  
Keyword(s):  
Best Management Practices ◽  
Management Practices ◽  
Spline Interpolation ◽  
Planting Date ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Corn Hybrids ◽  
Important Region ◽  
Soil Temperatures

The Transylvanian Plain, Romania is an important region for agronomic productivity. However, limited soils data and adoption of best management practices hinder land productivity. Soil temperatures of the Transylvanian Plain were evaluated using a set of twenty datalogging stations positioned throughout the plain. Soil temperatures were monitored at the surface and at 10, 30, and 50 cm depths, and soil moisture was monitored at 10 cm. Preliminary results indicate that most soils of the Transylvanian Plain will have a mesic temperature regime. However, differences in seasonal warming and cooling trends across the plain were noted. These have important implications for planting recommendations. Growing degree days (GDDs) are preferred over maturity ratings, because they can account for temperature anomalies. The crop being considered for this study was corn. The base temperature (BT) was set at 10oC, and the upper threshold was 30oC. Two methods were used to calculate GDDs; 1) minimum and maximum daily temperatures, and 2) 24 h of averaged temperature data. Growing degree days were run from 110-199 day of year (DOY) to represent approximate planting date to tasseling. The DOY that 694 accumulated growing degree days (AGDDs) was reached at each site was then analyzed to identify differences across the TP. Three sites failed to reach 694 AGDDs by DOY 199, and were excluded from comparisons to other results. Averaged values were used to create spline interpolation maps with ArcMap 9.2 (ESRI, Redlands, CA, USA). The southeastern portion of the TP was found to tassel a month earlier assuming a planting date of 109 DOY. Four DeKalb® corn hybrids were then selected based on GDDs to tasseling, drydown, drought tolerance, and insect resistance. With a better understanding of the GDD trends across the TP, more effective planting and harvesting could be accomplished by Romanian farmers to maximize agronomic production.

PREDICTION OF SOIL TEMPERATURE FROM AIR TEMPERATURE FOR ESTIMATING CORN EMERGENCE

1990 ◽  
Vol 70 (3) ◽  
pp. 619-628 ◽  
Author(s):  
L. M. DWYER ◽  
H. N. HAYHOE ◽  
J. L. B. CULLEY
Keyword(s):  
Nonlinear Response ◽  
Zea Mays L ◽  
Thermal Environment ◽  
Growing Degree Days ◽  
Degree Days ◽  
Emergence Period ◽  
Air Temperatures ◽  
Soil Temperatures ◽  
Production Areas ◽  
Zone Temperature

The soil thermal environment is critical to corn (Zea mays L.) emergence in short-season production areas. A field study was therefore carried out during the emergence period to test a method to predict 0.05-m soil temperatures from air temperatures and to develop a method to quantify emergence rates as a function of actual and predicted soil thermal units. Thermal units (base 10 °C) were calculated from hourly air and measured and predicted 0.05-m soil temperatures; these thermal units were fit to test emergence data collected on six cultivars. The nonlinear response of percentage emergence to thermal units was approximated by an exponential function. Comparisons of cultivar emergence rates, expressed as the number of thermal units to 0 and 75% emergence, statistically differentiated (P ≤ 0.05) the test cultivars into three main groupings. When predicted soil temperatures were used to calculate the number of thermal units, the thermal units to specific emergence levels were within the equivalent of 1 or 2 d of those generated using measured soil temperatures.Key words: Growing degree days, regression, thermal regimes, seed zone temperature, corn emergence

A TEMPERATURE-DEPENDENT MODEL OF EGG DEVELOPMENT OF THE WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA LECONTE (COLEOPTERA: CHRYSOMELIDAE)

1991 ◽  
Vol 123 (6) ◽  
pp. 1183-1197 ◽  
Author(s):  
A.W. Schaafsma ◽  
G.H. Whitfield ◽  
C.R. Ellis
Keyword(s):  
Simulation Model ◽  
Diabrotica Virgifera Virgifera ◽  
Base Temperature ◽  
Diabrotica Virgifera ◽  
Degree Days ◽  
Egg Development ◽  
Egg Hatch ◽  
Developmental Threshold ◽  
Soil Temperatures ◽  
Developmental Rates

AbstractDevelopmental rates of post-diapause eggs of Diabrotica virgifera virgifera LeConte were compared in the laboratory at six constant temperatures, 12, 16, 20, 24, 28, and 32°C. Linear and nonlinear models were fitted to temperature versus developmental data and were used to predict egg hatch in the field. A four-parameter model fitted to median developmental rates (r2 = 0.99) indicated that development was linear between 16 and 28°C, optimal at 28°C, and decreased at 32°C. The lower development threshold (± SE) (10.5 ± 0.1°C) was determined by linear regression and the x-intercept method. Completion of post-diapause egg development required 258 ± 3 degree-days (± SE) above the base temperature. This compared well with the mean degree-days accumulated to 50% hatch (± SE) of 265 ± 24 which we observed in the field at several locations over 3 years using a degree-day model incorporating an 11°C developmental threshold and soil temperatures at 5- and 10-cm depths. A stochastic simulation model, incorporating a nonlinear developmental function dependant on soil temperatures taken every 2 h also predicted 50% hatch within 2 days. This model was validated in the field with 19 independent records of soil temperatures for several locations at two depths in the soil over 3 years. The simulation model accurately predicted time of 5 and 95% hatch, which indicates that this model has broad application in predicting the pattern of egg hatch for pest management.

scholarly journals Optimum timing of fungicides for control of onion white rot (Sclerotium cepivorum)

2008 ◽  
Vol 61 ◽  
pp. 393-393 ◽  
Author(s):  
J.L. Tyson ◽  
R.A. Fullerton ◽  
R.W. Chynoweth ◽  
P.A. Rheinlander ◽  
G.N. Hill
Keyword(s):  
Disease Onset ◽  
White Rot ◽  
Optimal Timing ◽  
Base Temperature ◽  
Degree Days ◽  
Poor Control ◽  
Sclerotium Cepivorum ◽  
Application Analysis ◽  
Soil Temperatures ◽  
Accumulated Degree Days

Onion white rot caused by Sclerotium cepivorum continues to be a major fungal disease of onions in New Zealand The onset of the disease in the Pukekohe area can be predicted by the use of cumulative average daily soil temperatures above a base temperature (white rot degree days) This prediction model was used to determine the optimal timing for fungicide application Analysis of data from trials on timing of fungicide applications conducted between 19892007 showed a correlation between the efficacy of fungicide programme and accumulated degree days with later start times in relation to disease onset equating to a consistent drop in efficacy The disease normally occurs when white rot degree days reach 250 Fungicide programmes commenced above this value achieved relatively poor control Spray programmes should start before the disease is observed in the field with start times between 100 and 200 white rot degree days achieving the best control

MODIFICATION OF THE HEAT UNIT FORMULA FOR PEAS

1962 ◽  
Vol 42 (1) ◽  
pp. 15-21 ◽  
Author(s):  
G. W. Hope
Keyword(s):  
Daily Maximum ◽  
Base Temperature ◽  
Heat Unit ◽  
Yearly Variation ◽  
Coefficients Of Variation ◽  
Maximum Temperatures ◽  
Unit Formula

The yearly variation in computed heat unit requirements of Perfection peas was reduced by modifying the method of deriving the units. Coefficients of variation of heat unit sums derived from daily means were lowest when daily maximum temperatures in excess of 60°F. were equated to 60° and when a base temperature of 36°F. was subtracted from the mean.Heat unit sums obtained from daily maxima were as homogeneous as those obtained from daily means.

Quantification of vegetative development of faba bean, oats, and Italian ryegrass

2012 ◽  
Vol 63 (12) ◽  
pp. 1097 ◽  
Author(s):  
M. Mohammed Yusoff ◽  
D. J. Moot ◽  
B. A. McKenzie ◽  
G. D. Hill
Keyword(s):  
Soil Temperature ◽  
Faba Bean ◽  
Simulation Models ◽  
Italian Ryegrass ◽  
Base Temperature ◽  
Degree Days ◽  
Vegetative Development ◽  
Forage Crops ◽  
Air Temperatures ◽  
Leaf Appearance

This study quantified the relationship between vegetative development and temperature of ‘Old New Zealand’ faba bean, ‘Milton’ oats, and ‘Feast II’ Italian ryegrass using thermal time (Tt, degree-days) calculations. Each species was sown on five dates in autumn and winter 2008 and three dates in autumn 2009. The linear model for rate of development calculated the Tt requirement of faba bean for 75% emergence as 217 degree-days (base temperature (Tb) = 1.2°C), compared with 132 (Tb = 1.6°C) for oats and 132 (Tb = 1.8°C) for Italian ryegrass. Leaf appearance had a Tb of 2.4°C for faba bean, 3.0°C for oats, and 0.7°C for Italian ryegrass. The mean phyllochron (degree-days leaf–1) was 66 ± 1 for faba bean, 123 ± 3.90 for oats, and 120 ± 4.21 for Italian ryegrass. Soil temperature at 20 mm depth was the most accurate predictor of Tb and the Tt requirements to reach 75% emergence. Conversely, air temperature on-site was required to predict the phyllochron for faba bean because of its elevated growing point. Either air or soil temperature at the experimental site or at a nearby meteorological station could be used to define the phyllochron for oats and Italian ryegrass. These results highlight the importance of both soil and air temperatures to accurately define vegetative development before the processes are included in simulation models for these winter annual forage crops.

scholarly journals Onset of Flowering in Biennial and Perennial Garden Plants

2012 ◽  
pp. 85-132
Author(s):  
F. T. Last ◽  
A. M.I Roberts
Keyword(s):  
Late Winter ◽  
Base Temperature ◽  
Early Winter ◽  
Species Trees ◽  
Air Temperatures ◽  
Winter Temperatures ◽  
Soil Temperatures ◽  
Significant Temperature ◽  
Spring Temperatures ◽  
Delayed Flowering

Observations were made weekly over a period of 30 years of 208 species (trees, shrubs, herbaceous plants and geophytes) from more than 1,000 growing in a garden located 18km east of the Royal Botanic Garden Edinburgh (RBGE), Scotland (lat. 55º 56ʹN: long. 3º 09ʹW). Of these species, 27 were British native or naturalised.The First Flowering Dates (FFD) of 67 species were without significant temperature association with variable weather; the FFDs of the other 141 species reflected, in contrast, the net outcome of ‘major’ associations with late winter/spring temperatures and smaller impacts of autumn/early winter temperatures. Increases in late winter and spring temperatures advanced the onset of flowering in the current year; in contrast, increases in autumn and early winter temperatures tended to be associated with delayed flowering in the following year.With stepwise regression, penalised signal regression and thermal-time models, it was possible to identify species with ‘strong’ associations with both air and soil temperatures and species with ‘weak’ associations with either air or soil temperatures.Thermal-time models for each of 120 species, whose FFDs were associated with temperature, enabled the characterisation of (1) base temperatures, Tb(°C), at, and above which, development towards open flowers is possible; and (2) thermal constants (degree days accumulated between the start of development and the onset of flowering). Together these attributes suggested that each base temperature cohort has species with widely different degree-day requirements. Between 1978 and 2007 mean air temperatures significantly increased by 0.080°C, 0.044°C and 0.026°C yrˉ¹ in the first, second and third quarters; soil temperatures increased by 0.060ºCyrˉ¹in the first quarter. Over the 30-year period, the trends in flowering showed the early (February/March) flowering species flowering c. 24 days sooner; the later flowering species (April/May) advanced by only c. 12 days.

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