Prediction Models for Chilling and Heat Requirements to Estimate Full Bloom of Almond Cultivars in the Central Valley of Chile

Ramirez, L.; Sagredo, K.; Reginato, G.

doi:10.17660/actahortic.2010.872.12

Cited by 24 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Almond chill accumulation was calculated for November and December because the best estimation of the chilling requirement for almond (Ramirez et al 2010) is generally fulfilled by mid-December in California. Based on the best estimates of the chilling requirement of California's pistachio cultivars (Ferguson et al 2008), pistachio's chill needs are met in mid-to-late February.…”

Section: Chill Accumulationmentioning

confidence: 99%

“…Recent quantification has estimated the budbreak-based chilling requirement of Nonpareil as 23 CPs (Ramirez et al 2010). The chilling requirements for pollinizer cultivars used in California have not been estimated using the Dynamic model but based on the quantification using other models, likely only differ from Nonpareil by a few CPs (Rattigan and Hill 1986;Alonso et al 2005).…”

Section: Almondmentioning

confidence: 99%

“…Chilling requirements and subsequent requirements of spring heat that results in budbreak are then statistically fit to many years of data. The most common approach is some variation on Ashcroft et al (1977), selecting the chilling accumulation that results in the least variation of heat accumulations that precede budbreak (Ramirez et al 2010;Rattigan and Hill 1986) or the chilling and heating accumulation that minimizes the error in the predicted day of budbreak (Chuine et al 1998;Legave et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Following the approach of Pope et al (2013), Bayesian nonparametric function estimation was used to estimate this yield-based chilling requirement for each crop. Because the chilling requirement in almond is quite low (Ramirez et al 2010), it was doubted that there would be years in the record with chill low enough to impact yield. Thus, the relationship between almond yield and chill was analyzed as a proof of concept, expecting to find no relationship between chill and yield.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Nut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds

et al. 2014

View full text Add to dashboard Cite

TitleNut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds Abstract Warming winters due to climate change may critically affect temperate tree species. Insufficiently cold winters are thought to result in fewer viable flower buds and the subsequent development of fewer fruits or nuts, decreasing the yield of an orchard or fecundity of a species. The best existing approximation for a threshold of sufficient cold accumulation, the "chilling requirement" of a species or variety, has been quantified by manipulating or modeling the conditions that result in dormant bud breaking. However, the physiological processes that affect budbreak are not the same as those that determine yield. This study sought to test whether budbreak-based chilling thresholds can reasonably approximate the thresholds that affect yield, particularly regarding the potential impacts of climate change on temperate tree crop yields. County-wide yield records for almond (Prunus dulcis), pistachio (Pistacia vera), and walnut (Juglans regia) in the Central Valley of California were compared with 50 years of weather records. Bayesian nonparametric function estimation was used to model yield potentials at varying amounts of chill accumulation. In almonds, average yields occurred when chill accumulation was close to the budbreak-based chilling requirement. However, in the other two crops, pistachios and walnuts, the best previous estimate of the budbreak-based chilling requirements was 19-32 % higher than the chilling accumulations associated with average or above average yields. This research indicates that physiological processes beyond requirements for budbreak should be considered when estimating chill accumulation thresholds of yield decline and potential impacts of climate change.

show abstract

Section: Chill Accumulationmentioning

confidence: 99%

Section: Almondmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Both of these studies were made in Spain. Studies made in Chile found that the chilling requirements ranged from 200-400 CU (Ramírez and Reginato 2010). Once the chill accumulation is met, endodormancy is broken.…”

Section: Chilling and Heat Requirementsmentioning

confidence: 99%

Effect of Evapotranspiration Rate on Almond Yield in California

Serrano¹

View full text Add to dashboard Cite

Effect of Evapotranspiration Rate on Almond Yield in California Dafne Isaac SerranoSince 2011, California has been under drought conditions. These conditions have not only affected water availability for farmers, but also production. California's second most valuable crop, almonds, has been affected by drought conditions. This study used three models (Model 1-3) to describe almond yield variability from year to year and almond yield variability within a year in Kern County, CA. The study evaluated 185 almond farms that were classified in three locations (east side, west side and north west side). The years of the study were 2011 (wet year) and 2013-2015 (drought condition years). Model 1 determined a functional regression between almond yield and annual evapotranspiration during the 4 years of the study. The R 2 was 7.9%, meaning low association between both variables and high unexplained variability (92.1%). Model 2 evaluated year to year variation. A regression function between almond yield and annual evapotranspiration after adjusting for location, precipitation, chilling hours and year was made. The R 2 of this model 62.6%, and all the variables used had a p<0.05. The R 2 was higher than Model 1; however, there was high unexplained variability (47.4%). Model 3 evaluated within-year variation. A regression function between almond yield and annual evapotranspiration after adjusting for tree age and location (east, west and northwest side) was made for each year (2011 and 2013 -2015). Coefficient of variation of evapotranspiration and soil available water storage were analyzed as additional variables in Model 3; however, they were not introduced in Model 3 due to the low increase in R 2 in each year (<2%). The R 2 of Model 3 for each year were, 60.4%, 49.7%, 53.8% and v 53.2% for the years 2011, 2013-2015, respectively. Model 3 also had high unexplained almond yield variability in each year (39.6%-50.3%). This high unexplained variability leads to introduce additional variables to the functional regression model for further studies. Identifying these additional variables and having a functional regression model with high R 2 would lead to understand how low evapotranspiration could potentially lead to a positive response on yield in drought conditions; thus, making farmers improve water use efficiency and hence, lowering production cost. However, the high unexplained variability clearly indicates that evapotranspiration is only one of many factors that influence yield. If improved yield is an important outcome, future studies must examine large-scale almond-producing farms with multiple agricultural system variables.

show abstract

Impact of future warming on winter chilling in Australia

Darbyshire

Webb

Goodwin³

et al. 2012

Int J Biometeorol

View full text Add to dashboard Cite

Increases in temperature as a result of anthropogenically generated greenhouse gas (GHG) emissions are likely to impact key aspects of horticultural production. The potential effect of higher temperatures on fruit and nut trees' ability to break winter dormancy, which requires exposure to winter chilling temperatures, was considered. Three chill models (the 0-7.2°C, Modified Utah, and Dynamic models) were used to investigate changes in chill accumulation at 13 sites across Australia according to localised temperature change related to 1, 2 and 3°C increases in global average temperatures. This methodology avoids reliance on outcomes of future GHG emission pathways, which vary and are likely to change. Regional impacts and rates of decline in chilling differ among the chill models, with the 0-7.2°C model indicating the greatest reduction and the Dynamic model the slowest rate of decline. Elevated and high latitude eastern Australian sites were the least affected while the three more maritime, less elevated Western Australian locations were shown to bear the greatest impact from future warming.

show abstract

Prediction Models for Chilling and Heat Requirements to Estimate Full Bloom of Almond Cultivars in the Central Valley of Chile

Cited by 24 publications

References 0 publications

Nut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds

Nut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds

Effect of Evapotranspiration Rate on Almond Yield in California

Impact of future warming on winter chilling in Australia

Contact Info

Product

Resources

About