Relationship between temperature and flowering in almond: effect of location

1987 ◽  
Vol 27 (6) ◽  
pp. 905 ◽  
Author(s):  
K Rattigan ◽  
SJ Hill
Keyword(s):  
Continuous Function ◽  
Threshold Temperature ◽  
Chilling Requirement ◽  
Flowering Date ◽  
Hourly Temperature ◽  
Single Location ◽  
Growing Degree Hours ◽  
Chill Unit ◽  
Maximum Temperatures ◽  
Different Climates

A model for the prediction of flowering date in almond requires estimates of the chilling and heat sum requirements. We estimated hourly temperatures from daily minimum and maximum temperatures. A continuous function relating hourly temperature to rate of chilling was used to calculate daily chill unit accumulations. Heat sums were measured as growing-degree-hours: the linear accumulation of hourly temperatures above a threshold temperature. Our model was tested with estimates derived from data obtained at 1 French and 2 Australian locations. The results indicate that estimates derived from data at a single location can be successfully used for other locations with different climates. The accuracy of flowering date prediction generally improves as the number of locations and years of data on which it is based increase. The predictions for the cultivars Mission and Nonpareil were within 5 days of the observed dates in 73 and 88% respectively of the locations-years examined. We concluded that the chilling requirement in almond is (mean � s.e.) 284 � 33 chill units and 3 groups of cultivars can be identified with respect to heat sum requirement in the ranges 5300-6300; 6800-7700 and 8200-8900 degree hours above 4.5�C.

Relationship between temperature and flowering in almond

1986 ◽  
Vol 26 (3) ◽  
pp. 399 ◽  
Author(s):  
K Rattigan ◽  
SJ Hill
Keyword(s):  
Continuous Function ◽  
Floral Development ◽  
Chilling Requirement ◽  
Flower Buds ◽  
Daily Minimum ◽  
Growing Degree Hours ◽  
Chill Unit ◽  
Temperature Records ◽  
Maximum Temperatures ◽  
Climate Station

Records of flowering in 12 almond cultivars over 7 years, together with temperature records from a standard climate station, were used to estimate the chilling requirement for dormancy break in flower buds and the heat sum requirements for floral development in each cultivar. Hourly temperatures were estimated from daily minimum and maximum temperatures. A continuous function relating hourly temperatures to rate of chilling was used to calculate daily chill unit accumulations. Requirements of 220-320 chill units were estimated and calculated heat sum requirements ranged from 5300 to 8900 growing-degree-hours above 4-5�C. These requirements were used to estimate the dates of 50% flowering for 1958-84.

scholarly journals Phenotypic Variation of Length of Bud Dormancy in Apple Cultivars and Related Malus Species

1991 ◽  
Vol 116 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Roberto Hauagge ◽  
James N. Cummins
Keyword(s):  
Bud Dormancy ◽  
Leaf Fall ◽  
Winter Conditions ◽  
Cu Accumulation ◽  
Malus Species ◽  
Growing Degree Hours ◽  
Chill Unit ◽  
Apple Cultivars ◽  
The Mean ◽  
Subtropical Environment

The chilling requirements (CR) to break bud dormancy in a broad range of apple cultivars (Malus ×domestica Borkh.) and related Malus spp. were assessed by periodic sampling and forcing of field-grown shoots as a function of chill unit (CU) accumulation and/or by the total growing degree hours (GDH) accumulated from leaf fall until the time of budbreak under a simulated subtropical winter. The mean number of CU required to break dormancy of field overwintered shoots varied between 218 ± 113 for `Anna' and 1516 ± 113 for `Wright #1'. However, most genotypes had CR between 800 and 1200 CU. Much wider variation for the length of bud dormancy was observed in plants growing under simulated subtropic winter conditions. Genotypes that had shown the lowest CR values under Geneva, N.Y., winters generally had the highest year-to-year variation in CR estimates. Cultivar bud CR values obtained under cold winters are related to field-observed CR estimates in a subtropical environment, but absolute values may differ markedly. Furthermore, several genotypes that show reasonable adaptation to the subtropics have similar or higher CR than apple cultivars with standard CR under Geneva conditions. In addition, enough CU accumulated under the simulated subtropic winters to break dormancy of standard apple cultivars. However, complete dormancy removal was observed only in cultivars well-adapted to a subtropical environment. This result indicates that in addition to CU accumulation, there are important interactions among cultivars and environmental factors that are responsible for terminating bud dormancy. Several cultivars and wild species have shown resistance to delayed foliation. Among the species, M. brevipes, M. rockii, M. spectabilis, and M. turesii are more tolerant than M. baccata and its hybrids, which are recognized for their adaptation to the subtropic environment.

Prediction of temperatures in cattle dung for estimating development times of coprophilous organisms

1988 ◽  
Vol 78 (2) ◽  
pp. 235-240 ◽  
Author(s):  
J. N. Matthiessen ◽  
M. J. Palmer
Keyword(s):  
Air Temperature ◽  
Meteorological Data ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Threshold Temperature ◽  
Cattle Dung ◽  
Daily Maximum ◽  
Daily Minimum ◽  
Maximum Temperatures ◽  
Minimum Air Temperature

AbstractIn studies in Western Australia, temperatures in air and one- and two-litre pads of cattle dung set out weekly and ranging from one to 20 days old were measured hourly for 438 days over all seasons, producing 1437 day x dung-pad observations. Daily maximum temperatures (and hence thermal accumulation) in cattle dung pads could not be accurately predicted using meteorological data alone. An accurate predictor of daily maximum dung temperature, using multiple regression analysis, required measurement of the following factors: maximum air temperature, hours of sunshine, rainfall, a seasonal factor (the day number derived from a linear interpolation of day number from day 0 at the winter solstice to day 182 at the preceding and following summer solstices) and a dung-pad age-specific intercept term, giving an equation that explained a 91·4% of the variation in maximum dung temperature. Daily maximum temperature in two-litre dung pads was 0·6°C cooler than in one-litre pads. Daily minimum dung temperature equalled minimum air temperature, and daily minimum dung temperatures occurred at 05.00 h and maximum temperatures at 14.00 h for one-litre and 14.30 h for two-litre pads. Thus, thermal summation in a dung pad above any threshold temperature can be computed using a skewed sine curve fitted to daily minimum air temperature and the calculated maximum dung temperature.

Mathematical Model for Design Conditions for Cooling Load Calculations

1981 ◽  
Vol 103 (2) ◽  
pp. 328-334 ◽  
Author(s):  
D. Kohli
Keyword(s):  
Mathematical Model ◽  
Numerical Procedure ◽  
Barometric Pressure ◽  
Daily Temperature ◽  
Temperature Deviation ◽  
Average Value ◽  
Hourly Temperature ◽  
Temperature Ranges ◽  
Maximum Temperatures ◽  
T Distribution

A numerical procedure using Newton-Raphson technique is used for finding wet bulb temperature from observed dry bulb temperature relative humidity and barometric pressure. Assuming maximum temperatures and daily temperature ranges of the day as random variables, maximum temperatures and daily ranges are estimated from samples of ten years data by t-distribution for various confidence limits. A parameter called “Average Hourly Temperature Deviation” is defined and its effect on Equivalent temperature differential is demonstrated. A mathematical model for finding out optimum daily temperature distribution has been developed. An average value of the “Average Hourly Temperature Deviation” is chosen as the optimality criterion. The procedures are demonstrated by numerical examples and the design conditions for 20 major cities of India are provided in tabular form.

scholarly journals Evaluation of Chilling and Heat Requirements in Japanese Apricot with Three Models

HortScience ◽  
2012 ◽  
Vol 47 (12) ◽  
pp. 1826-1831 ◽  
Author(s):  
Zhihong Gao ◽  
Weibing Zhuang ◽  
Liangju Wang ◽  
Jing Shao ◽  
Xiaoyan Luo ◽  
...  
Keyword(s):  
Dormancy Breaking ◽  
Japanese Apricot ◽  
Flowering Date ◽  
Fruit Species ◽  
Chilling Requirements ◽  
Low Correlation ◽  
Growing Degree Hours ◽  
Heat Requirements ◽  
Chill Portions ◽  
Very High

Estimating chilling requirements is crucial for identifying appropriate cultivars for a given site, for timing applications of dormancy-breaking chemical agents, and for predicting consequences of climate change. For temperate-zone fruit species such as japanese apricot, productivity is reduced when chilling requirements are not adequately satisfied. In our study, we obtained chilling and heat requirements for flowering of six japanese apricot cultivars, which spanned the range of flowering times in this species for three successive years. Different methods for determining chilling requirements were evaluated and compared, and correlations among chilling requirements, heat requirements, and flowering date were established. The dynamic model proved to be the best for determining the chilling requirements of japanese apricot. The results showed a range of chilling requirements ranging from 26.3 to 75.7 chill portions and a narrow range of heat requirements, from 1017.7 to 1697.3 growing degree-hours (GDH). A very high correlation (R = 0.9797) between flowering date and chilling requirements and a low correlation (R = 0.4298) between flowering date and heat requirements suggest that flowering date in japanese apricot is mainly a consequence of the chilling requirements of the different genotypes, whereas heat requirements contribute a limited effect to the variation in flowering dates. Chilling requirements and heat requirements were positively related with a low correlation coefficient (R = 0.4211).

scholarly journals VARIATIONS IN COLD HARDINESS CHARACTERISTICS AMONG PRUNUS SPECIES

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1081c-1081
Author(s):  
S. Kadir ◽  
E. L. Proebsting
Keyword(s):  
Cold Hardiness ◽  
Xylem Vessel ◽  
Chilling Requirement ◽  
Prunus Species ◽  
Flower Buds ◽  
Flower Primordia ◽  
Vessel Elements ◽  
Chill Unit

Flower buds of 20 Prunus species representing 4 subgenera were collected during winter and spring of 1989-90. Buds were preconditioned at +3° or 7°C to test their minimum hardiness level (MHL) or the rate of hardiness increase. DTA revealed that most of the prunus species have flower primordia that supercool. The subgenus Padus have racemose inflorescences and do not deep supercool during dormancy. P. besseyi, P. nigra and P. americana had small exotherms between -22° and -27°C while P. davidiana and P. subhirtella had larger exotherms at higher temperatures. Exposure of flower buds to -7°C shifted LTES to lower temperatures and/or reduced the size of LTE, which became undetectable for many species including P. nigra and P. americana. P. davidiana and P. subhirtella increased hardiness by 6°/day at -7° while dormant. Deacclimation coincided with an increase in LTE50 and the development of xylem vessel elements in the bud axis, calyx and filaments as indicated by dye movenent. P. davidiana was the least hardy species and required only 700 chill units to satisfy the chilling requirement, while P. nigra and P. americana had LTE average of -26°C at MHL and required over 1000 chill unit accumulation.

scholarly journals The Dynamic Model Provides the Best Description of the Chill Process on ‘Sirora’ Pistachio Trees in Australia

HortScience ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 420-425 ◽  
Author(s):  
Jianlu Zhang ◽  
Cathy Taylor
Keyword(s):  
Dynamic Model ◽  
Dynamic Models ◽  
Historical Data ◽  
Chilling Requirement ◽  
Pistacia Vera ◽  
Field Validation ◽  
Winter Chill ◽  
Growing Degree Hours ◽  
Historical Data Analysis ◽  
Chill Portions

Determining the chilling requirement for ‘Sirora’ pistachio (Pistacia vera L.) production in Australia and monitoring winter chill accumulation is desirable to allow growers to take timely mitigating action in years of insufficient chill. Based on greenhouse work, historical data analysis, and field validation, the Chilling Hour, Utah, and Dynamic Models were compared. The Dynamic Model produced the best determination for fulfillment of chilling requirement with 59 chill portions. The required number of growing degree-hours above 4.4 °C from chill fulfillment to 50% bloom was 9633. Relations among the level of fulfillment of chilling requirement, bloom delay, and yield are discussed.

scholarly journals Using a Chill Unit/Growing Degree Hour Model to Assess Spring Freeze Risks for `Redhaven' Peach Trees

HortScience ◽  
1990 ◽  
Vol 25 (11) ◽  
pp. 1382-1384 ◽  
Author(s):  
Joanne Logan ◽  
Dennis E. Deyton ◽  
David W. LockWood
Keyword(s):  
Prunus Persica ◽  
Temperature Data ◽  
Peach Tree ◽  
Full Bloom ◽  
Air Temperatures ◽  
Growing Degree Hours ◽  
Chill Unit ◽  
Peach Trees ◽  
Peach Orchard

Peach [Prunus persica (L.) Batsch] production in Tennessee has declined since 1985 due to the occurrence of freezing temperatures that kill the buds, usually in the spring. Analyses of long-term (1951-89) daily temperature data from four locations in Tennessee were used to evaluate the freeze risks for `Redhaven' peach tree buds at those sites. A model using daily accumulated chill units and growing degree hours (base 4.4C air temperature) was used to estimate the dates to begin and end chill unit accumulations and the dates of full bloom of `Redhaven' peach trees for each year in the climatological record. The actual dates of freezes with air temperatures at or below –2.2C and the estimated bud developmental stage on the date of each freeze also were determined. The model was tested using peach orchard records and was found to be an improvement over using only freeze data. The model indicated that Spring Hill had the highest risk for peach production and Jackson the lowest. Recent problems with spring freezes at Knoxville and Spring Hill were due to later than normal freeze dates rather than earlier development of the `Redhaven' peach tree buds. At Springfield, the recent freeze problems were due to earlier breaking of rest, earlier full bloom, and later freezes.

scholarly journals Studies in the dynamics of disinfection. VI. Calculation of a new and constant temperature coefficient for the reaction between phenol and Bact. coli

1946 ◽  
Vol 44 (4) ◽  
pp. 249-255 ◽  
Author(s):  
R. C. Jordan ◽  
S. E. Jacobs
Keyword(s):  
Temperature Coefficient ◽  
Constant Temperature ◽  
Point Of View ◽  
Phenol Concentration ◽  
Maximum Temperature ◽  
Threshold Temperature ◽  
Temperature Coefficients ◽  
Maximum Temperatures ◽  
Relationship Of ◽  
The Relationship

1. The virtual sterilization time (v.s.t.) has been used as a measure of the rate of disinfection of Bact. coli cultures by phenol under carefully standardized conditions. The relationship of this time to temperature at each of five phenol concentrations has been examined from a fresh point of view, since it has previously been shown (Jordan & Jacobs, 1946) that none of the commonly accepted temperature coefficients was satisfactorily constant.2. The relationship is such that a minimum or threshold temperature exists for each concentration. A corresponding ‘maximum’ temperature has been fixed, defined as the temperature at which the v.s.t. is 10 min. The value of (v.s.t. – 10) thus varies from infinity to zero between these temperature limits.3. Sigmoid curves are obtained when log (v.s.t. –10) is plotted against temperature for given phenol concentrations. These may be regarded as asymptotic to ordinates at the minimum and maximum temperatures.4. The Pearl-Verhulst logistic equation gives a curve of the required sigmoid type, and this formula has been shown to fit the curves of log (v.s.t. – 10) against temperature very satisfactorily over the range of concentrations studied.5. One of the constants of this formula partakes of the nature of a temperature coefficient, and it has, therefore, been possible to derive a truly constant temperature coefficient for each phenol concentration.6. The values of this new temperature coefficient do not vary greatly with phenol concentration within the range studied, but it is not yet possible to establish whether it is essentially constant for all phenol concentrations with which it is possible to work.

scholarly journals Comparison of Chilling Requirement in `Ta Tao' Budded Peach Trees by Shoot Forcing

HortScience ◽  
2000 ◽  
Vol 35 (4) ◽  
pp. 562A-562
Author(s):  
P.G. Gibson ◽  
G.L. Reighard
Keyword(s):  
Chilling Requirement ◽  
Crna Probe ◽  
Flower Bud ◽  
Bud Emergence ◽  
Growing Degree Hours ◽  
Dormant Season ◽  
Probe Hybridization ◽  
Shoot Forcing ◽  
Set Up ◽  
Peach Trees

Peach trees exposed to `Ta Tao' vegetative chip bud grafts have been shown to have physiological changes that include bloom delay, delayed maturity, reduced shoot vigor, and early autumn defoliation. `Ta Tao' is known to be infected with the graft transmissible agent Peach Latent Mosaic Viroid (PLMVd). PLMVd has been associated with bloom delay and reduced shoot vigor. `Coronet' peach trees planted in a high-density, Y-trained orchard system were treated with vegetative chip buds from `Ta Tao'. Transmission of PLMVd was confirmed in the treated trees by cRNA probe hybridization. A shoot forcing study was set up to determine if exposure to `Ta Tao' would alter the chilling requirement of `Coronet' peach. Terminal fruiting shoots were collected periodically during the dormant season from 8 Jan. 1999 to 19 Feb. 1999, which represented a range of chill hour accumulation from 574 to 927, respectively. Shoots were forced in a greenhouse, and chilling requirement was considered complete when 50% of the flowers opened. Chilling requirement was not changed by exposure to `Ta Tao' chip buds. The number of days required for shoots to bloom was significantly and consistently longer for the `Ta Tao' treated trees. The number of shoots responding to forcing conditions was significantly less in the treated trees. The data suggest that the graft transmissible effects from `Ta Tao' buds increased the growing degree hours required for `Coronet' leaf and flower bud emergence after rest completion under greenhouse forcing conditions.

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