scholarly journals Effective heat unit summation and base temperature on the development rice plant. II On heading, flowering, kernel development and maturing of rice.

1990 ◽  
Vol 59 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Morie EBATA
Keyword(s):  
Rice Plant ◽  
Base Temperature ◽  
Heat Unit ◽  
Kernel Development ◽  
Effective Heat

DEVELOPMENT AND SURVIVAL OF AXENICALLY REARED MOUNTAIN PINE BEETLES, DENDROCTONUS PONDEROSAE (COLEOPTERA: SCOLYTIDAE), AT CONSTANT TEMPERATURES

1985 ◽  
Vol 117 (2) ◽  
pp. 185-192 ◽  
Author(s):  
L. Safranyik ◽  
H. S. Whitney
Keyword(s):  
Developmental Stages ◽  
Incubation Temperature ◽  
Adult Stage ◽  
Base Temperature ◽  
Heat Unit ◽  
Mountain Pine Beetles ◽  
Mountain Pine ◽  
Development Times ◽  
Temperature Heat ◽  
Pine Beetles

AbstractThe development and survival of mountain pine beetles axenically reared on standardized diet at 8 constant temperatures (10°–35 °C) were observed. At 32 °and 35 °C, 22 and 18% of the eggs hatched and all larvae died within 10 d of hatching. At the lower temperatures, 60–70% of the eggs hatched. The highest survival for all developmental stages was at 24 °C. At 10° and 15 °C development of all beetles reared in bolts of lodgepole pine or on axenic diet stopped when larvae were fully developed, whereas at 24 °and 27 °C all of the beetles developed normally to the adult stage. Larvae that had stopped developing during rearing at 15 °C resumed development after being transferred to 24 °C, indicating that pupation was limited by temperature. Although mean development times to the larval, pupal, and adult stages all decreased with increasing incubation temperature, heat-unit requirements above a base temperature of 5.6 °C were lowest for individuals reared at 27 °and 24 °C for all developmental stages. At these temperatures, an estimated average of 673 and 674 degree-days above 5.6 °C were required for development from egg to the tanned (dark) adult stage, respectively. The average widths of the prothorax and the sex ratios of axenic beetles were within published ranges. Mean development times and heat-unit requirements at constant temperatures for development to various life stages agreed well with published field and laboratory studies from western Canada.

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.

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 Predicting Yield and Time to Maturity of Muskmelons from Weather and Crop Observations

1998 ◽  
Vol 123 (2) ◽  
pp. 195-201 ◽  
Author(s):  
Sylvie Jenni ◽  
Katrine A. Stewart ◽  
Gaétan Bourgeois ◽  
Daniel C. Cloutier
Keyword(s):  
Total Yield ◽  
Developmental Time ◽  
Daily Maximum ◽  
Base Temperature ◽  
Heat Unit ◽  
Data Set ◽  
Simple Method ◽  
Fruit Maturity ◽  
Richards Function ◽  
Maximum Temperatures

A simple method to predict time from anthesis of perfect flowers to fruit maturity (full slip) and yield is presented here for muskmelon (Cucumis melo L.) grown in a northern climate. Developmental time for individual muskmelons from anthesis to full slip could be predicted from several heat unit formulas, depending on the temperature data set used. When temperature at 7.5 cm above soil level was used, the heat unit formula resulting in the lowest coefficient of variation (cv=6.9%) accumulated daily average temperatures with a base temperature of 11 °C and an upper threshold of 25 °C. With temperatures recorded at a meteorological station located 2 km from the experimental field, the method showing the lowest cv (8.9%) accumulated daily maximum temperatures with a base temperature of 15 °C. This latter method was improved by including a 60-degree-day lag for second cycle fruit. The proportion of fruit volume at full slip of 22 fruit from the first cycle could be described by a common Richards function (R2=0.99). Although 65% of the plants produced two fruit cycles, fruit from the first cycle represented 72% of total yield in terms of number and mass. The blooming period of productive flowers lasted 34 days, each cycle overlapping and covering an equal period of 19 days. Counting the number of developing fruit >4 cm after 225 degree days from the start of anthesis (when 90% of the plants have at least one blooming perfect flower) could rapidly estimate the number of fruit that will reach maturity.

scholarly journals Determining Heat Unit Requirements for Broccoli Harvest in Coastal South Carolina

1997 ◽  
Vol 122 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Robert J. Dufault
Keyword(s):  
South Carolina ◽  
Standard Method ◽  
Growing Season ◽  
Base Temperature ◽  
Degree Days ◽  
Heat Unit ◽  
Mean Temperature ◽  
Coefficients Of Variation ◽  
The Mean ◽  
The Difference

The objective of this research was to determine the least variable method to predict the dates of the first and last broccoli (Brassica oleracea L. var Italica) harvests based on heat unit summation using coefficients of variation (cv). The method with the lowest cv for predicting first harvest was to sum, over days from planting to harvest, the difference between the growing season mean (GSM) temperature and a base temperature of 7.2 °C. If the GSM maximum (max) temperature, however, was >26.7 °C, an adjusted max temperature was calculated by first subtracting 26.7 °C from the GSM max temperature and then subtracting the GSM mean temperature. Then the growing degree days (GDDs) were summed by subtracting the base temperature of 7.2 °C from the average of the GSM minimum (min) and adjusted max temperatures. This method produced a cv of 3.96 compared to 4.13 for the standard method of summing over the entire growing season, the mean temperature minus the base temperature of 4.4 °C. The method with the lowest cv for predicting last harvest was to sum, over days from planting to harvest, the difference between the GSM max temperature and a base temperature of 7.2 °C. If the GSM max temperature, however, was >29.4 °C, the base temperature was subtracted from 29.4 °C and not the actual GSM max temperature. This method produced a cv of 3.71 compared to 4.10 for the standard method of summing over the growing season, the mean temperature minus the base of 4.4 °C.

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