Search

To clarify the influence of climate change on the flowering phenology of Yoshino cherry at its southern distribution limit, we examined the relationship between cold exposure for endodormancy release (chilling requirement) and heat requirement for bud growth on Hachijojima Island, Japan, from 1948 to 2024. Cold exposure and heat requirement had a significant relationship approximated by linear or log-linear functions. In years with less cold exposure, the first flowering dates were much later than normal, in accordance with the higher heat requirement. Our results indicate that the variation in the balance between cold exposure and heat requirement depending on the pattern of annual air temperature change is likely to vary the first flowering date greatly at the distribution limit of Yoshino cherry. [ABSTRACT FROM AUTHOR]

Numerous studies have documented that climate change will considerably impact grapevine phenology. In the 2024 growing season, notable differences emerged from the previous five years, between 2019 and 2023. Rising temperatures at the beginning of the growth cycle of grapevines began the phenology phases earlier, leading to earlier bud burst and flowering for various grape varieties in many regions of Türkiye. This study examines variations in phenological phases across different years, using short-term climate data from a weather station in a cv. Sultan 7 (Vitis vinifera L.) vineyard in Yunusemre, Manisa, Türkiye. The objective of the study is to determine the impact of temperature fluctuations ranging from January to September on grapevine phenology intervals during critical stages: bud burst, full bloom, veraison, and maturity, specifically for between 2019 and 2024. Evaluations focused on critical factors, including growth cycle duration, days within specific temperature ranges, effective heat summation for the variety, and the Winkler Index values. The 2024 growing season recorded the highest temperatures in April and June, and bud burst occurred 5 days (2021) to 10 days (2019) earlier, while full bloom was determined for 16 days (2019 and 2022) to 27 days (2021) earlier than in previous years. The findings showed that years characterized by earlier flowering, 2024 (day of the year (DOY) 120) and 2022 (DOY 136), may be associated with earlier harvest. In addition, the Winkler Index recorded a highest of 2945.01 growing degree days (GDD) in 2024, with a specific effective heat summation value of 2,138.79 GDD for variety in a shorter timeframe. The findings suggest that although the intervals between veraison and harvest tend to remain almost similar each year, early flowering, the ripening period, and elevated temperatures before veraison in the same season can greatly contribute to prompting an earlier harvest. [ABSTRACT FROM AUTHOR]

This article explores the use of temperature sum models in studying plant spring phenology. These models measure plant development based on temperature-dependent units, such as growing degree hours. The article discusses the limitations of determining the threshold temperature, which represents the lower limit for development, and suggests that it should be estimated for each species. It also examines the implications of using temperature response models as proxies for true physiological responses. The research emphasizes the importance of developing ecophysiological growing degree hour models that consider the unique characteristics of different plant species. Another study focuses on the use of growing degree hour models to predict the timing of spring phenological events in subtropical trees. It finds that using a fixed threshold temperature in these models may lack biological realism, but can still be useful for comparing heat requirements between species or bud types. The authors stress the need for experimental determination of the temperature response and the use of species-specific values in growing degree hour models. [Extracted from the article]

The ongoing global climate change has aroused interest in the spring phenology of woody species in boreal and temperate regions that require cold temperatures to break bud dormancy. Most research on this topic has been concentrated on fruit species, rather than forest trees. We studied the effect of chilling duration in vitro and ex vitro on the timing of dormancy release in European ash plants. In vitro chilling (at 4–5ºC) of rooted ash plants delayed their subsequent growth when planted out in the greenhouse, and the length of delay correlated with chilling duration. The fastest growth was observed after 5–7 weeks of cold treatment, whereas 13 weeks reduced the plant viability. The impact of cold treatment for 300–3000 h was assessed on one-year-old ash plantlets. Subsequently, clonal micropropagation of European ash on a dihydroquercetin (taxifolin)-containing medium significantly reduced the requirement for chill temperatures: the plantlets came out of endodormancy after having accumulated 500 chill hours, whereas control (unchilled) plantlets required more than 1000 h. The budburst period was also significantly shorter in chilled plants. We suppose that the effect might have been due to the antioxidant activity of the flavonoid dihydroquercetin. The thermal time requirement for budburst in European ash was well described as an inverse exponential function of the number of chill hours at ≤ 5 °C. Late-flowering and photoperiod-insensitive European ash is a good object for studying the impact of external and internal factors on the mechanisms behind the induction and release of dormancy. [ABSTRACT FROM AUTHOR]

Previous studies have shown a negative correlation between chilling accumulation (CA) and heat requirements (HRs) in peaches (Prunus persica (L.) Batsch), consistent with findings in other plants in spring events. However, there is a lack of comparative research on the CA–HR relationship in peach varieties with different chilling requirements (CRs), and the specific impact of CA on HR reduction remains poorly described. To address this, we investigated the effects of CA on the days and HR for flowering in 54 peach varieties of differing CRs. Scanning electron microscopy was used to observe the effects of CA on the phenology of floral organ development in a selected peach variety. Our results indicate that, in general, peaches exhibit a reduced HR and accelerated flowering as the CA increases, but that the strength and trend of the CA–HR relationship is influenced by the CR and the variety. Low-CR varieties showed less sensitivity to CA increments, requiring higher relative increases in CA to significantly lower the HR, whereas high-CR varieties appeared to be more sensitive, with even modest changes leading to substantial reductions in HR. However, variations from this generality exist, even within varieties displaying the same rCA (the ratio of CA to CR). Additionally, we provide a summary of the relationship between the rCA and drHR in peaches of differing CRs, and identify several varieties exhibiting a strong response in the CA–HR relationship. This study also highlights the impact of CA on flower bud development, revealing slower progression under lower CA levels and accelerated growth with an increased CA. In particular, we identified the critical period of the enlargement and initiation of green scales as indicative of successful pollen grain formation. Finally, we present a schematic of the CA–HR relationship for flowering in peaches. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phenological shifts in peaches have been observed over the last few years due to the fluctuation of the seasonal climate conditions experienced during dormancy, affecting orchard management practices and influencing production and harvest dates. This study aimed to model the vegetative and floral budbreak of selected peach cultivars. Three peach cultivars, including "Rubyprince", "Harvester", and "Red Globe", were considered in this study based on the representation of the early, early-mid, and mid-seasons. The prediction of the budbreak in peaches was assessed using different models that integrate the combination of chill and heat requirements. Models used include the Weinberger model, the modified Weinberger model, Utah, the dynamic model, and the growing degree model. The accumulation of chill varies according to the season evaluated. A model that considers both chill and heat accumulation is presented for each cultivar. Budbreak as an indicator of dormancy completion was established for each cultivar. The outcome of this study is to determine the amount of chilling accumulation and thermal time required to mark the beginning of the budbreak in selected cultivars with a model that predicts the duration of the dormancy. These results are valuable information that can be used for crop management practices and support the mitigation of cold damage during this critical period of crop development. [ABSTRACT FROM AUTHOR]

Impact of climate change affects chilling and heat accumulation that phenological development of plant needs, air temperature being determinant for flowering, pollination and fruit production, but few knowledges are available in the winter and spring climate of Tétouan. The physiological mechanisms of the reproductive cycle that controls pollen emission are related with temperature, and different environmental factors regulate strongly the reproductive phases of the plant's life cycle. However, from an empirical point of view, the alternance between endodormancy and ecodormancy is not well detectable. Our work focuses on determining the heat accumulation periods associated with the thermal balance needed to fulfill the chilling and heat required for budbreak and bloom timing. To evaluate Morus, Pistacia, Quercus and Olea response to changes in chill and heat accumulation rates, the Dynamic Model and the Growing Degree-Days Method were used. Regression analyses identified the chilling and forcing periods for these taxa. Over the past 12 years, chill accumulation during tree dormancy increased significantly for most of woody taxa studied, while heat accumulation decreased not significantly for all taxa. Heat accumulation was the main driver of bloom timing, with effects of variation in chill accumulation. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study aims to generalize cultivar-specific tree phenology responses to winter and spring temperatures and assess the effectiveness of the Tabuenca test and various chill and heat accumulation models in predicting bloom dates for a wide range of climatic conditions and years. To this end, we estimated the dates of rest completion and blooming and correlated them with observed bloom dates for 14 peach and nectarine cultivars that were evaluated in 11 locations across Europe (Greece, France, Italy, Romania and Spain), within the EUFRIN cultivar testing trial network. Chill accumulation varied considerably among the studied sites, ranging from 45 Chill Portions (CP) in Murcia-Torre Pacheco (Spain) to 97–98 CP in Cuneo (Italy) and Bucharest (Romania). Rest completion occurred latest or was not achieved at all for some cultivars in the southern sites in Murcia. Dormancy release happened earliest in Bucharest and Cuneo, sites where heat accumulation had a strong influence on the regulation of bloom time. Blooming occurred earliest in the moderately cold regions of Lleida (Spain) and Bellegarde (France), and 7–11 days later in the warmer locations of Rome (Italy) and Naoussa (Greece), suggesting that bloom timing is strongly influenced by delayed rest completion in these locations. The Dynamic Model resulted in both more homogeneous chill accumulation across years and better predictions of bloom dates, compared with the Utah, Positive Utah and Chilling Hours models. Prediction of bloom dates was less successful for low-chill cultivars than for medium- and high-chill cultivars. Further climatic and experimental data are needed to make estimates of the climatic needs of peach cultivars more robust and to generate reliable advice for enhancing the resilience of peach production under varying and changing climatic conditions. [ABSTRACT FROM AUTHOR]

Key message: The flowering time of wild almond species studied herein is more influenced by heat requirement, which partly justifies also the differences in flowering date during the different years in genotypes. Bloom frost tolerance, chilling and heat requirements can influence distribution and productivity of almond species. Both laboratory and field-related methods were employed to determine the chilling and heat requirements as well as bloom frost tolerance of several early-, mid- and late-flowering genotypes of two wild almond species (Prunus scoparia (Spach) C. K. Schneid and P. elaeagnifolia Spach). The variations of carbohydrates and soluble solids in the wood and buds were also measured during chilling period in laboratory method. Furthermore, the tolerance to spring-frost was evaluated using electrolyte leakage method. Results showed that in field method, the chilling requirement in P. scoparia ranged from 344 to 682 CU, whereas P. elaeagnifolia exhibited chilling requirements between 313 and 415 CU. The greatest chilling requirement was observed in the early-flowering genotype of P. scoparia. The heat requirement in P. scoparia ranged from 2737 to 9149 GDH, while this parameter varied from 4985 to 7788 GDH in P. elaeagnifolia. The highest heat requirement was observed in the late-flowering P. scoparia. The laboratory method failed to measure chilling and heat requirement of P. scoparia, due to sever bud abscission, but the chilling requirement of P. elaeagnifolia ranged from 383.33 to 450 h in this method, which was slightly higher than that of field method. Measurements of plants internal chemicals showed that prolonged duration of chilling is contributed to more extensive degradation of carbohydrates which results higher soluble solids' content. The highest tolerance to bloom frost was observed in the early-flowering P. elaeagnifolia (– 5.3 °C), while the lowest tolerance was recorded in the late-flowering P. scoparia (– 3.8 °C). There was a negative association between bloom's frost tolerance and soluble solids' content. [ABSTRACT FROM AUTHOR]

Aim: The aims of this study were to evaluate the changes in the length of the time period between leaf‐out and flowering across temperate tree species, and associate these changes with potential physiological and environmental drivers to enhance mechanistic insight into these phenomena. Location: Central Europe. Time period: 1980–2016. Major taxa studied: Six temperate woody species. Methods: Statistical analyses were carried out based on long‐term ground observations of both spring leaf‐out and flowering across temperate tree species during 1980–2016, a period characterized by rapid warming. Results: The temperature sensitivity of flowering (−5.4 ± 0.04 days/℃, mean ± SE) was higher than that of leaf‐out (−4.6 ± 0.04 days/℃) across all species, regardless of whether leaf‐out occurred before or after flowering. This study postulates a hypothesis attributing the different temperature sensitivities to different thermal sensitivities, thermal requirements, and photoperiodic controls. Main conclusions: The larger temperature sensitivity of flowering than leaf‐out resulted in an extended time period between flowering and leaf‐out in species that bloom before leafing out, but a shorter time period between these phenophases in species with the opposite strategy. We would like to emphasize the importance of changes in time period between different phenophases, and we recommend conducting experimental research to reveal the underlying mechanisms of plant phenology response to climate change, and to explore its potential ecological implications. [ABSTRACT FROM AUTHOR]

Bud break timing in peach [Prunus persica (L.) Batsch] is determined by the sequential fulfillment of a chilling requirement (CR) and a heat requirement (HR) for development. Genotypic variation in CR has been well characterized in peach. Adapting peaches to low chilling environment through reduced CR can make them susceptible to crop destroying spring frosts, if bloom occurs too early. Potential variation in HR between accessions has received less attention due to the methodological difficulty in assessing HR independently of CR. HR could vary in the magnitude of growing degree hours (GDHs) and/or the base temperature at which GDH accumulation begins. Characterizing HR traits in peach accessions could allow improved bloom time modeling and selection of phenotypes with improved spring frost avoidance through delayed bloom. We estimated GDH and apparent base temperature for floral bud break by observing time to floral bud break at several constant forcing temperatures. We evaluated 54 peach accessions (representing a range of CR) in which chilling had been saturated after >1,700 h at 3°C. Accessions differed widely in both the GDH requirement (2,015 to 11,191°C⋅h) and apparent base temperature (−1.85 to 8.69°C) for GDH accumulation. GDH and apparent base temperature were negatively correlated. A simulation exercise was performed to assess relative importance of varying base temperature vs. GDH for delaying bloom at different chilling accumulations at three locations in the southeastern United States using 30 years of historical weather data. The aim of this study was to determine whether there may be unrecognized diversity in peach germplasm for two HR traits (base temperature and thermal time) to enable breeding efforts to delay floral bud break and reduce the frost exposure risk of developing flowers and fruits. Our results suggest that selecting cultivars for increased GDH would be a safer, more reliable strategy for delaying bloom than increasing base temperature for GDH accumulation.

Temperate deciduous fruit trees survive winter temperatures by entering a dormant phase in their aerial meristematic organs. Release from bud dormancy occurs after chill requirements (CR) have been satisfied, whereas bud burst/flowering follows heat requirement (HR) fulfillment. The physiological basis behind these metrics remains elusive. In this study, we are presenting the first multidisciplinary dormancy progression analysis in northern Patagonia, linking (1) forcing/field phenology, (2) bud anatomical development, and (3) soluble sugar (sucrose, glucose, and fructose) dynamics in Juglans regia L. CR and HR were determined for ‘Chandler’ and ‘Franquette,’ two walnut cultivars with markedly different CR, in artificial chill/forced heat trials (three seasons) and in-field chill/forced heat tests (five seasons) using excised twigs either with or without apical buds (non-decapitated and decapitated). The soluble sugar dynamics of ‘Chandler’ (high-performance liquid chromatography) and the anatomical changes of the buds (light microscopy) of the two cultivars were analyzed during endo-ecodormancy progression in one and two seasons, respectively. The CR defined by artificial chill tests proved to be an overestimation compared to the field determinations. Moreover, HR was the main driver in the phenology dynamics, as expected for a high-chill region. ‘Chandler’ showed an average of 10.3 field chill portions (CP) and 2,163 Growing Degree Hours (GDH°C) less than ‘Franquette’ for dormancy release and bud burst, respectively. These results were consistent with the transition of the shoot apex from the vegetative to the reproductive phase and the soluble sugar profile. The decrease in sucrose between 15 and 30 days after CR fulfillment could be a reliable biological marker for endodormancy release in walnut, while the increase in fructose and glucose is likely an osmolyte and cellulosic carbon source in pre-sprouting. In addition, we discuss the effect of paradormancy thanks to our apical bud experiment (with or without). Our results improve the current understanding of endo-ecodormancy progression in walnut and provide insightful results for walnut production (i.e., cultivation practices such as pruning) as well as for further application in dormancy modeling, to infer the ideotypes that should be bred for future climate conditions.

Bud break timing in peach [ Prunus persica (L.) Batsch] is determined by the sequential fulfillment of a chilling requirement (CR) and a heat requirement (HR) for development. Genotypic variation in CR has been well characterized in peach. Adapting peaches to low chilling environment through reduced CR can make them susceptible to crop destroying spring frosts, if bloom occurs too early. Potential variation in HR between accessions has received less attention due to the methodological difficulty in assessing HR independently of CR. HR could vary in the magnitude of growing degree hours (GDHs) and/or the base temperature at which GDH accumulation begins. Characterizing HR traits in peach accessions could allow improved bloom time modeling and selection of phenotypes with improved spring frost avoidance through delayed bloom. We estimated GDH and apparent base temperature for floral bud break by observing time to floral bud break at several constant forcing temperatures. We evaluated 54 peach accessions (representing a range of CR) in which chilling had been saturated after >1,700 h at 3°C. Accessions differed widely in both the GDH requirement (2,015 to 11,191°C⋅h) and apparent base temperature (−1.85 to 8.69°C) for GDH accumulation. GDH and apparent base temperature were negatively correlated. A simulation exercise was performed to assess relative importance of varying base temperature vs. GDH for delaying bloom at different chilling accumulations at three locations in the southeastern United States using 30 years of historical weather data. The aim of this study was to determine whether there may be unrecognized diversity in peach germplasm for two HR traits (base temperature and thermal time) to enable breeding efforts to delay floral bud break and reduce the frost exposure risk of developing flowers and fruits. Our results suggest that selecting cultivars for increased GDH would be a safer, more reliable strategy for delaying bloom than increasing base temperature for GDH accumulation. [ABSTRACT FROM AUTHOR]

Temperate deciduous fruit trees survive winter temperatures by entering a dormant phase in their aerial meristematic organs. Release from bud dormancy occurs after chill requirements (CR) have been satisfied, whereas bud burst/flowering follows heat requirement (HR) fulfillment. The physiological basis behind these metrics remains elusive. In this study, we are presenting the first multidisciplinary dormancy progression analysis in northern Patagonia, linking (1) forcing/field phenology, (2) bud anatomical development, and (3) soluble sugar (sucrose, glucose, and fructose) dynamics in Juglans regia L. CR and HR were determined for 'Chandler' and 'Franquette,' two walnut cultivars with markedly different CR, in artificial chill/forced heat trials (three seasons) and in-field chill/forced heat tests (five seasons) using excised twigs either with or without apical buds (non-decapitated and decapitated). The soluble sugar dynamics of 'Chandler' (high-performance liquid chromatography) and the anatomical changes of the buds (light microscopy) of the two cultivars were analyzed during endo-ecodormancy progression in one and two seasons, respectively. The CR defined by artificial chill tests proved to be an overestimation compared to the field determinations. Moreover, HR was the main driver in the phenology dynamics, as expected for a high-chill region. 'Chandler' showed an average of 10.3 field chill portions (CP) and 2,163 Growing Degree Hours (GDH°C) less than 'Franquette' for dormancy release and bud burst, respectively. These results were consistent with the transition of the shoot apex from the vegetative to the reproductive phase and the soluble sugar profile. The decrease in sucrose between 15 and 30 days after CR fulfillment could be a reliable biological marker for endodormancy release in walnut, while the increase in fructose and glucose is likely an osmolyte and cellulosic carbon source in pre-sprouting. In addition, we discuss the effect of paradormancy thanks to our apical bud experiment (with or without). Our results improve the current understanding of endo-ecodormancy progression in walnut and provide insightful results for walnut production (i.e., cultivation practices such as pruning) as well as for further application in dormancy modeling, to infer the ideotypes that should be bred for future climate conditions. [ABSTRACT FROM AUTHOR]

Greenhouses are artificial growing environments that can provide the growth factors required for the production of crop plants out of season. In these structures, the low temperature values that occur during the year cause losses in yield and quality because they are not suitable for plant cultivation. In order to be able to grow out of season in these periods, the amount of heat required by the plants should be provided with additional heating. In the study carried out to determine the amount of heat needed in greenhouses throughout the year for the provinces of Kırşehir and Kahramanmaraş, which are located in two different regions of Turkey, the heat requirements that will arise in the presence or absence of a thermal screen in greenhouses with the same characteristics were calculated. In the calculations, the most common tomato plant grown in both provinces has been considered. Accordingly, if the greenhouse temperature is kept at a constant temperature of 18°C throughout the year, the heat energy requirements that emerge during the year are 469.90 kWh m.-2 for Kırşehir and 254.71 kWh m.-2 for Kahramanmaraş. In the case of using a thermal screen, these values were calculated as 401.53 kWh m.-2 for Kırşehir province and 218.91 kWh m.-2 for Kahramanmaraş province. As a result of the study, the amount of heat energy needed in greenhouses in provinces decreased with the use of thermal screens. It has been determined that this situation is extremely important in terms of reducing the share of heating in production costs and the amount of carbon dioxide released into the atmosphere by fossil energy sources used for heating purposes. [ABSTRACT FROM AUTHOR]

The present study aims to generalize cultivar-specific tree phenology responses to winter and spring temperatures and assess the effectiveness of the Tabuenca test and various chill and heat accumulation models in predicting bloom dates for a wide range of climatic conditions and years. To this end, we estimated the dates of rest completion and blooming and correlated them with observed bloom dates for 14 peach and nectarine cultivars that were evaluated in 11 locations across Europe (Greece, France, Italy, Romania and Spain), within the EUFRIN cultivar testing trial network. Chill accumulation varied considerably among the studied sites, ranging from 45 Chill Portions (CP) in Murcia-Torre Pacheco (Spain) to 97–98 CP in Cuneo (Italy) and Bucharest (Romania). Rest completion occurred latest or was not achieved at all for some cultivars in the southern sites in Murcia. Dormancy release happened earliest in Bucharest and Cuneo, sites where heat accumulation had a strong influence on the regulation of bloom time. Blooming occurred earliest in the moderately cold regions of Lleida (Spain) and Bellegarde (France), and 7–11 days later in the warmer locations of Rome (Italy) and Naoussa (Greece), suggesting that bloom timing is strongly influenced by delayed rest completion in these locations. The Dynamic Model resulted in both more homogeneous chill accumulation across years and better predictions of bloom dates, compared with the Utah, Positive Utah and Chilling Hours models. Prediction of bloom dates was less successful for low-chill cultivars than for medium- and high-chill cultivars. Further climatic and experimental data are needed to make estimates of the climatic needs of peach cultivars more robust and to generate reliable advice for enhancing the resilience of peach production under varying and changing climatic conditions.

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heat requirements in greenhouses are calculated considering greenhouse type, the climate of the region and temperatures desirable for plant growth. Calculations made according to daily average temperature values lead to misleading results during periods when temperatures are high and under conditions when greenhouse temperature is kept low. For this reason, determining heat requirements according to hourly values provides more accurate results. Calculations of heat requirements in greenhouses are based on the difference between the desired temperature in the greenhouse and the outside temperature. However, in unheated greenhouses and those that are not ventilated until a specific temperature, actual temperature values are higher than outside temperatures. For this reason, heat requirement calculations should be made according to hourly climate values taking into account actual temperature in the greenhouse and temperature rise resulting from greenhouse specifications. This study aims to compare the amounts of fuel consumed under real conditions with fuel consumption calculated with conventional methods using inside and outside temperature difference and considering the above mentioned inconveniences. Daily fuel consumption calculated theoretically differs from actual consumption values. However, in comparisons based on fuel amounts consumed on an annual basis, best results were obtained when temperature rise in the greenhouse was taken into consideration. In the event that temperature rise is taken into consideration, a 3% difference is observed between calculated fuel consumption and actual fuel consumption.

Winter chill is expected to decrease in many of the suitable growing regions for deciduous trees. Argentinean North Patagonia hosts extensive fruit tree cultivation, which provides an important contribution to both local and global food security. Using historic records from 11 weather stations from North Patagonia, we evaluate the possible impacts of climate change on fruit tree cultivation. We assess winter chill and seasonal heat availability, and the risk of spring frost events based on outputs from 15 Global Climate Models (GCMs) for two Representative Concentration Pathway (RCP) scenarios and two future time periods (represented by central years 2050 and 2085). Metrics were estimated for 47 years of records from the weather stations, as well as typical conditions for 10 past scenarios and 60 future GCM and RCP projections. Scenarios consisted of 100 plausible annual temperature records produced by a weather generator. Results suggest that fruit tree dormancy in Argentinean North Patagonia will not be strongly affected by climate change. Compared to the past, winter chill may only decrease by 9% in the RCP4.5 scenario by 2050 in the northeastern and eastern subregion, while in the central‐south and west the reduction seems unlikely to exceed 6% by the same RCP scenario and year. Our models project stable high growing season heat in the northeastern and eastern regions, and major increases in the south by 2085 in both RCP scenarios. Projections of spring frost events varied between 0 and about 25 hours below 0°C depending on the site. Increasing heat availability may create opportunities for fruit and nut growers to introduce new species and cultivars to the region. Our results provide a basis for planning such introductions and for enabling growers to exploit new opportunities for producing temperate orchard crops beyond their traditional ranges. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For temperate-zone fruit species, a certain total heat requirements are needed in order to obtain mature fruits. Fruit development process changes in different fruit groups. Determination of fruit growth stage and heat requirements are the most important cultural practice in orchard management, such as time of irrigation, fertigation, thinning and harvesting, etc. This study was conducted on heat requirements, fruit growth and development of 'Bella d'lmola', 'San Castrese' and 'Sungiant' apricot cultivars in Sanliurfa (Turkey) during 2011 and 2012. Heat requirements in the phenological period from dormancy breaking to fruit maturation period were determined in apricot cultivars. Fruit weight and fruit volume of three apricot cultivars were determined at five-day intervals from fruit setting till fruit harvest. Fruit sampling for TSS and titratable acid contents was made with ten day intervals just after thirty five days of full bloom and with five day intervals at the close harvest stage. The total heat requirements between bud swelling (BBCH Code: 51) and fruit maturation period (BBCH Code: 89) in apricot cultivars was determined as 21 333 ('Bella d'lmola') - 25 024 ('Sungiant') GDH. In these cultivars, three developmental stages were observed as "fast,"- "slow,"- and "fast" during the fruit growth. The significant increases in fruit weight and volume in all apricot cultivars were observed during the third growth stage. During the growth period of fruit TSS content continuously increased, whereas titratable acid content decreased. It was determined that the cultivars for fruit maturation should pass at least 65 ('Bella d'lmola') - 80 days ('San Castrese') after full blooming. [ABSTRACT FROM AUTHOR]

Introduction:Dormancy is one of the most important stages in the life cycle of temperate plants and plants are required to exit from it with supply of chill unit. Flowering is defined with chilling and heat requirement. Owing to low chilling requirement, blooming happens too early and cold temperatures produce an important loss of yield by frost. In temperate fruits, awareness of the need buds to avoid winter frost is one of the main objectives in breeding programs. Studies concerning chilling and heat requirements are thus of special interest in these species, being very important for the choice of parents in breeding programs to create superior varieties of winter and spring frost (late flowering and resistant cold) provide. Utah is one of the most important model was introduced in 1974 by Richardson and colleagues. Effective temperature on cold storage in Utah model is 1/9-5/2. This is 6/1-9/12 in North Carolina and 8/1-9/13 in low chilling. Temperatures above 16 have negative effect on accumulation in Utah model. Later models were developed according to the Utah model that the Low chilling requirement (18) and the North Carolina (31) models are among them. Apricot (Prunus armeniaca L.) is belonging to warm temperate regions and due to the lack of compatibility and apricot spring frost in Khorasan Razavi province, the identification of varieties and genotypes with high compatibility and high thermal and cooling requirements to reduce the risk of early frost and increase production efficiency, seems important. The purpose of this study was to determine the need for chilling and heat requirement in apricot cultivars. Material and methods: In this research, chilling and heating requirements of four local cultivars of apricot were evaluated under field and laboratory conditions. This experiment was conducted at agricultural research station Golmakan. A factorial (two-factor) experiment was laid out in a completely randomized design with tree replications. First factor was various apricot cultivars (Noori- Dirras, Mashhad- Dirras, Shams Mashhad and Mashhad-44) and the second factor was chilling hours in five levels (0,100,300,500,700). About 45 branches of deciduous trees of each variety were collected when the temperature was below 7 °C. Finally, samples were taken in the greenhouse with an average temperature of 23° C and 16 hours of light and flowering percentage was recorded. For determination of chilling requirement in Utah, low chilling requirement and the North Carolina was performed in CU and Heat based on the degree of development hours (GDH) was calculated. GDHs average hours of temperatures between 5-5 / 4 ° C) and for any amount of time, sleep disruption and blossoming flowers will be calculated by 50% (5). Data analysis was done by JMP 8 and Excel softwares. Results: There were significant differences (1%) between chilling hours, cultivars and their interactions on flowering percent. .Under laboratory condition, cultivars began flowering after 100 hours in 4°C.The results showed that there was a significant difference between 500 and 700 hours of chilling requirement. Most of the flowering was related to 700 hours and the lowest one was in control. There was a low difference in the chilling requirement. Heating requirement was 3300 growth degree hours (GDH) for Noori- Dirras and Shams Mashhad to 3379 GDH for Dirras- Mashhad and Mashhad-44 cultivars. Although little differences exist in flowering onset of cultivars, the differentiation of flowering period among cultivars was around one week. Various cultivars revealed little differences in flowering onset in locations they meet their chilling requirement. The chill units estimated by Utah model was 1588. Chill units in Low chilling model and North Carolina model was 1291 and 1331, respectively while in chill hours was about 1100. The heat units in Noori- Dirras, Shams Mashhad was about 3,300 and it were calculated 3379 for Dirras Mashhad and Mashhad-44, . The various models of chilling in the field conditions were calculated according to the Utah model. Chilling requirement by the North Carolina and Low chilling requirement models were calculated, respectively, 1331 and 1291 chill unit while in the chill hours, 1,100 hours were calculated for varieties. There was negative relationship between chill and heat requirement in flowering date.

Copyright of Mediterranean Agricultural Sciences is the property of Akdeniz Universitesi Ziraat Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] In this paper, the effect of high temperature on the release of natural dormancy of grape bud was studied. [Method] The dormant shoots of five grape varieties (Red earth, Manicure finger, Christmas rose, Auguste, Muscat hamburg) were used as trial materials, the effects of 4 gradient high temperature water hath treatments(40,50,60,70 °C) for 1 hour on grape's bud swelling, bud green and bud leaf expansion were investigated, and their heat requirements were calculated and analyzed with variance analysis. [Result] Four high temperature treatments had positive effects on the bud swelling of Manicure fingers and Christmas roses, only 40 °C had a positive effect on the bud swelling of the Red earth, 60 and 70 Tl had positive effects on the August, and the effect of high temperature treatment on the bud swelling of Muscat hamburg was negative effect; Four high temperature treatments had positive effects on the bud green of Muscat hamburg, 40 °C had a positive effect on the bud green of Manicure fingers, 40 and 50 °C had positive effects on the bud green of Christmas rose, and four high temperature treatments had negative effects on the green rate of Red earth and Auguste; Four high temperature treatments had positive effects on the bud leaf expansion of Muscat hamburg, 50 and 70 °C had positive effects on the leaf expansion of Red earth, 50 °C had positive effect on the leaf expansion of Manicure finger, and four high temperature treatments had negative effects on the bud leaf expansion of Christmas rose and Auguste; Four high temperature treatments had positive effects on the heat requirement of Manicure finger, Augustus and Rose, 40 and 50 had negative effects on the heat requirements of Christmas roses, and four high temperature treatments had negative effects on the heat requirement of the Muscat hamburg. [Conclusion]The effects of high temperature on the dormancy releases of grape bud of different varieties were different, and the effects of different high temperatures on the dormancy of the same grape bud were also different. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bamboos, widely distributed in tropical and subtropical regions and significant in ecological, economic and cultural values, are similar to trees in the above-ground growth and to geophytes in the below-ground structure. However, contrary to well-studied endodormancy and the related chilling requirement that synchronize the seasonal development of above-ground buds of tree species and the well-studied below-ground buds of geophytes, it is unknown whether bamboos demonstrate the endodormancy and chilling requirements as those of trees and geophytes, which limits our understanding of how bamboos phenology cope with climate change. Our work mainly examined the effect of temperature on the dormancy release of underground shoot buds of two important subtropical running bamboo species, Lei bamboo (Phyllostachys violascens) and Moso bamboo (Phyllostachys edulis). In the experiments, the bamboo seedlings were first subjected to different durations of natural chilling and subsequently to a regrowth test under high-temperature forcing conditions in whole-tree chambers. In the regrowth test the dormancy state of the shoot buds was examined by observing shoot development, i.e., the emergence of the new shoot aboveground, a significant spring phenological event in many bamboo species. The time required for shooting under the forcing conditions decreased with prolonged chilling, indicating that the shoot buds of these two bamboo species demonstrate the phenomena of endodormancy and a chilling requirement for endodormancy release. For Lei bamboo, the chilling requirement was estimated as 45 Chill Portions (CP) and heat requirement was 9978 ± 6713 GDH℃. As for Moso bamboo, the estimated chilling requirement was 35CP and heat requirement was 6713 ± 3087 GDH℃. Meanwhile, the Vegis effect (an interaction of previous chilling accumulation and forcing temperature) was also found in Lei bamboo: there was a large difference in the time required for shoot development between low and high forcing temperatures after short durations of chilling, but the difference decreased with prolonged chilling. It was also shown that bamboo shoot buds almost received the same heat requirements for emergence at different forcing temperatures under the same chilling requirements. Our results will improve the understanding of temperature regulation of spring phenology in subtropical bamboo forests and promote bamboo production and management. ● Shoot buds of subtropical running bamboo have an endodormancy period. ● Chilling requirement contributes to the release of endodormancy in shoot buds. ● The shoot bud's dormancy release depends on the interaction of chilling accumulation and forcing temperature. ● This study possibly suggests that evergreens geophytes demonstrate both ecodormancy and endodormancy. [ABSTRACT FROM AUTHOR]

This study presents the first evaluation of apple flowering phenology models using data from 14 sites across the globe. The dataset includes large variability in growing climates, a prerequisite to investigate phenology models for use in climate change applications. Two flowering stages, early and full, were investigated allowing for unique model evaluation based on both statistical performance and biological assumptions. Two overarching phenology models (Sequential and Chill Overlap) and two sub-models of chill (Dynamic and Triangular) and heat (GDH and Sigmoidal) were tested. Flowering times from the different sites illustrated the differing effects of contrasting winter and spring temperatures. Sites with similar springtime temperatures, but different winter temperatures, had different flowering patterns (warmer winter sites flowered later). Across all analyses, results from the Chill Overlap model were better than those from the Sequential model. Of the Chill Overlap models, those fitted with the Triangular or Dynamic chill model and the GDH heat sub-model performed well statistically and met the assumptions of the model across both flowering stages. The mild sites in the analysis were least well represented, regardless of model selection. This global evaluation demonstrated that flowering modelling in temperate fruit trees would progress through appropriate choices of overarching model, sub-models and parameters. [ABSTRACT FROM AUTHOR]

Carbon dioxide emission, one of the core cause of global warming and other threats of nonreversible environmental effects, is in focus today. Among the several methods of CO 2 emission mitigation, post-combustion carbon capture (PCC), based on absorberdesorber systems with amine absorbents, is one of the promising alternatives. The major anthropogenic CO 2 point sources are power plants, natural gas extraction units, oil refineries, cement factories, biogas plants, etc. As these CO 2 sources can be treated with a PCC absorber-desorber system, then these two units should cope with various conditions. To maintain a desired high removal efficiency, the capture unit must work in flexible conditions. The aim of this study is to evaluate the influence of the extent of the absorption of carbon dioxide on the overall performance of the acid gas removal process, considering that, generally, as the amount of removed CO 2 increases, the separation becomes more challenging. In this work a verified computer based process model for the absorber-desorber system is used. Aspen Plus ® professional flowsheet simulator is used for this purpose. Attention is paid on the proper operating parameters of a PCC absorber-desorber system for the case of increasing the CO 2 capture efficiency up to 99%. As alternative solutions for these cases different scenarios are considered: • the increase of the capacity of a classic configuration of an absorber-desorber system; • the introduction of a second absorber column as extending the absorption column height; • the possible use of two absorbers and two desorbers working in series. This work deals with the detailed study on maximizing CO 2 removal efficiency while maintaining the minimal energy consumption for the absorbent regeneration section. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a powerful greenhouse gas, whose massive presence in the atmosphere causes gradual global warming. Absorption by means of chemical solvents is the most commonly used process for CO 2 removal. It can be applied to gaseous streams in power plants, natural gas, and refinery gas. Amine scrubbing is widely considered the most mature technology for PCC (post-combustion CO 2 capture), and 30% wt. MEA aqueous solution can be taken as the baseline solvent to be used as reference for studies focused on modelling and simulation. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. The thermodynamic model exerts an influence also on the determination of the overall heat of absorption of the acid gas in the solvent, being the heat released at chemical equilibrium related to the extent of reactions. Its estimation is of paramount importance, since it is directly related to the energy requirement at the reboiler of the solvent regeneration column and determines the temperature profile along the absorber. The model used in this work has been previously validated by comparison with data of absorption performances with regard to mass transfer phenomenon. In this work, results obtained from simulations have been checked against experimental data, by focusing on the thermodynamic framework and its influence on the evaluation of the reboiler duty, for possible energy saving solutions in scale-up design. [ABSTRACT FROM AUTHOR]

We investigated spatial and temporal variations in the accumulated growing degree-days (AGDD) requirement for spring vegetation green-up onset on the Tibetan Plateau (TP) during the rapid warming period of 1998–2012, which is essential for understanding and modeling the spring vegetation phenological responses to climate change. Annual green-up date was determined by using a satellite-derived normalized difference vegetation index. The annual AGDD requirement was then determined as the sum of daily mean air temperatures above 0 °C over the dormancy period. Linear regression between the AGDD requirement and year was used to determine its temporal trend. Partial correlation analysis was used to assess factors controlling inter-annual variations in the AGDD requirement. We found the AGDD requirement was significantly different for different vegetation types and showed large spatial variations ranging from a few °C-days in cold and wet areas to more than 1000 °C-days in warm and dry areas of the TP. Despite the rapid warming and subsequent earlier green-up date, the AGDD requirement did not increase significantly over the period 1998–2012. Interestingly, we found that the inter-annual variations in AGDD requirement were extensively driven by the number of chilling days, while precipitation sum and insolation affected the AGDD requirement in limited areas. Although the winter warming reduced chilling accumulation on the TP, the AGDD requirement for vegetation green-up onset did not necessarily increase over 1998–2012, being insensitive to decline in the chilling accumulation. This suggested that the chilling requirement to break vegetation dormancy might be still fulfilled. In other words, the winter warming might not substantially affect the vegetation green-up process, since the reduction in chilling accumulation may not affect the dormancy break. However, the negative temporal correlation between the AGDD requirement and number of chilling days indicates that continued future warming may lead to a deficiency in chilling and thus an increase in AGDD requirement. [ABSTRACT FROM AUTHOR]

Three different models ( 7. 2 X , 0-7.2 X and Utah Model) foT estimating chilling requirements and two different models (Growing Degree Hours and Effective Temperature Model) were used to estimate the heat requirements of wolfberry cultivars, the chilling and heat requirements of 19 'wolfberry cultivars under protected culture were studied, and their correlations between chilling requirement and heat requirement w'ere established. The result showed that the different chilling and heat requirements of tested cultivars were observed. Their chilling requirements had slight difference, ranging between 480 h and 720 h( s£7. 2 X Model) or between 480 h and 787 h(0 -1.2 X Model) or between 553 C - U and 829 C U(Utah Model) ,tkc chilling requirement of the north cultivars was more than that of the southern cultivars. The heat requirements also had slight difference, ranging between3696 and 4704 growing degree hours(GDH) or betweenl43 X and 182 X ( Effective Temperature Model). No matter how to estimate the chilling or heat requirement under different models, both chilling and heat requirements of different varieties had no significant correlation. [ABSTRACT FROM AUTHOR]

Chilling requirement, together with heat requirement, which has an impact on the climatic distribution of the genotypes of tree species, determines the flowering date. It also played an important role in the protected cultivation of fruit trees. In our study, we estimated chilling requirements for breaking of dormancy and heat requirements for flowering for 2 successive years in 69 Japanese apricot cultivars of Nanjing (China). The chilling requirements of those Japanese apricot cultivars ranged from 24 to 82 chill portions according to the dynamic model, and the heat requirements of those cultivars fluctuated between 691.9 and 2634.7 growing degree hours. The Japanese apricot cultivars were classified into three groups according to their chilling requirements: the low chilling requirement cultivars with less than 50 chill portions, the medium chilling requirement cultivar ranging from 50 to 70 chill portions, and the high chilling requirement cultivars with more than 70 chill portions. In our study, cultivars originated in Guangdong of China generally have a low chilling requirements, and originated in Zhejiang and Jiangsu of China have a high chilling requirements. Cultivars with lower or higher chilling requirement are not suitable for introduction of Nanjing due to their abnormal phenotype. We also observed that the heat requirement of Japanese apricot had no obvious relationship with their origins. The determination of chilling requirements of 69 Japanese apricot cultivars provided some basis for their rationalized introduction and distribution, and was also important in a breeding program. Those results also expanded our understanding of the temperature responses of flower bud in Japanese apricot during the dormancy progress. [ABSTRACT FROM AUTHOR]

Aim of this study was to determine heat requirement for silkworm larval period of 27 days to ensure optimal environmental conditions in the rearing room in April and May. Firstly, when silkworm rearing started on April 20, it was determined that rearing room should be heated during the larval period. During this period, heat requirements of silkworm 1st, 2nd, 3rd, 4th and 5th instar stages were 2036.38, 1851.25, 1666.13, 647.94 and 1796.79 W/h, respectively. Secondly, when the rearing started on April 27, heat requirements of 1st, 2nd, 3rd, 4th and 5th instar stages were 2036.38, 1018.19, 833.36, 647.94 and 1796.79 W/h, respectively. Thirdly, when it started on May 1, heat requirements of 1st, 2nd, 3rd, 4th and 5th instar stages were 1203.31, 1018.19, 833.06, 647.94 and 1796.79 W/h, respectively. When rearing started on May 1, the heat requirement of the 1st instar stage was 40.9% less than that of April 20 and April 27. As silkworm released urine, the heat requirement of the 5th instar stage was higher than that of other periods. As a result, keeping in view the heat requirements and the development the of mulberry leaves, the rearing starting on May 1 was found to be the most suitable period compared to other two rearing periods. [ABSTRACT FROM AUTHOR]

Instead of the commonly used approach of conducting controlled experiments to estimate chilling and heat requirements (CR and HR) of fruit trees, the statistical method of Partial Least Squares (PLS) regression was applied to identify the CR and HR of apricot ( Prunus armeniaca L.) in Beijing, China by correlating first flowering dates of apricot with daily chilling and heat accumulation during 1963–2010. Three common chilling models (the 0–7.2 °C, Utah and Dynamic Models) and one forcing model (the Growing Degree Hour Model) were used to convert daily temperature data into daily chill and heat accumulation rates. The results indicated that PLS regression analysis is a useful approach to estimate the CR and HR of fruit trees wherever phenology and climate observations have been conducted for long periods. Use of all chilling models indicated similar chilling periods for apricot in Beijing (mid-September to early March), while the identified forcing period started in early January and extended to the first flowering date for each year. The Dynamic Model appeared to be the most accurate model with smallest year-to-year variation in chill accumulated during the chilling period (coefficient of variation of only 7.5%). Using the Dynamic Model for chill, and the Growing Degree Hour Model for heat quantification, the CR of apricot in Beijing was determined at 75 ± 6 Chill Portions (CP) and the HR at 3055 ± 938 Growing Degree Hours (GDH). [ABSTRACT FROM AUTHOR]

Recent studies have revealed large unexplained variation in heat requirement-based phenology models, resulting in large uncertainty when predicting ecosystem carbon and water balance responses to climate variability. Improving our understanding of the heat requirement for spring phenology is thus urgently needed. In this study, we estimated the species-specific heat requirement for leaf flushing of 13 temperate woody species using long-term phenological observations from Europe and North America. The species were defined as early and late flushing species according to the mean date of leaf flushing across all sites. Partial correlation analyses were applied to determine the temporal correlations between heat requirement and chilling accumulation, precipitation and insolation sum during dormancy. We found that the heat requirement for leaf flushing increased by almost 50% over the study period 1980-2012, with an average of 30 heat units per decade. This temporal increase in heat requirement was observed in all species, but was much larger for late than for early flushing species. Consistent with previous studies, we found that the heat requirement negatively correlates with chilling accumulation. Interestingly, after removing the variation induced by chilling accumulation, a predominantly positive partial correlation exists between heat requirement and precipitation sum, and a predominantly negative correlation between heat requirement and insolation sum. This suggests that besides the well-known effect of chilling, the heat requirement for leaf flushing is also influenced by precipitation and insolation sum during dormancy. However, we hypothesize that the observed precipitation and insolation effects might be artefacts attributable to the inappropriate use of air temperature in the heat requirement quantification. Rather than air temperature, meristem temperature is probably the prominent driver of the leaf flushing process, but these data are not available. Further experimental research is thus needed to verify whether insolation and precipitation sums directly affect the heat requirement for leaf flushing. [ABSTRACT FROM AUTHOR]

Torrefaction of Japanese cedar (TR) and in-situ vapor-phase pyrolytic reforming of volatile matter from TR (PYR) were investigated with three main objectives; quantification of the heats required for TR and PYR (Q TR and Q PYR , respectively), demonstration of high conversion of bio-oil into syngas by PYR without either catalyst or oxidizing agent, and clarification of effects of water washing of the cedar prior to TR on Q TR and Q PYR as well as the product distribution. The cedar was subjected to TR and PYR at temperatures of T TR = 250–350 °C and T PYR = 500–800 °C, respectively. Q TR was defined as the difference in enthalpy between the TR products at T TR and dry cedar at 25 °C, and determined from compound or elemental composition of char, bio-oil, water, and non-condensable gases. Q TR increased with T TR in a range of 1.0–4.0% of the cedar HHV, which could be covered by burning the gas and a small portion (0.5–13.0%) of bio-oil from TR at T TR ≥ 280 °C. The water washing removed substantial portions of the inherent alkali and alkaline earth metallic species. This resulted in slight increase in Q TR , 0.2–0.8%-HHV and decrease in the gas yield, in particular, those of CO and CO 2. PYR converted substantial portions of the bio-oil from TR at T TR = 300 °C. The bio-oil conversion into CO/H 2 –rich gas was 85–90% at T PYR = 800 °C. Q PYR , which was defined as the enthalpy difference between the volatile matter from TR at 300 °C and that from PYR at T PYR , increased with T PYR but as small as 1.4–5.8% of the cedar HHV. The water washing slightly decreased Q PYR , and this was quantitatively explained by slightly smaller bio-oil yield from TR of the water-washed cedar at T TR = 300 °C than that of the cedar. Q PYR was a function of decrease in the bio-oil yield by PYR, which was not influenced by the water washing. • Pyrolytic reforming of volatiles from torrefaction produced CO/H 2 –rich syngas. • The heat required for reforming increased in semi-linear function of temperature. • The chemical energies of the feedstocks were almost distributed to the products. • Selective removal of heavier components was difficult only by vapor-phase reforming. [ABSTRACT FROM AUTHOR]

Prediction of the timing of spring phenological events such as bloom and leaf-out has important uses in agricultural and ecological management and modeling. However, after decades of model comparison there remains no consensus model to predict the date of spring phenological events in perennial temperate trees across species and locations. This lack of consensus may be due to over-fitting resulting from high model complexity, use of parameters that have not been adequately validated, or omission of parameters that are sound biological indicators of dormancy breaking. The aim of this study was to construct spring phenology candidate models with biologically-based parameters and starting values to test hypotheses regarding chill accumulation duration and the impact of pre-bloom conditions. Bloom data for three cultivars of Prunus dulcis (almond) from three decades in California were analyzed. Across all three cultivars, models which accumulated chill until approximately 75% of the heat requirement had been met, and did not integrate pre-bloom conditions, were substantially supported by the data. This suggests cold temperatures affect dormancy breaking well after the chilling requirement has been met and bud break timing is not substantially impacted by environmental conditions just prior to bud break. Fitting spring phenology using biologically based starting values estimated from bud break records may allow for the development of improved predictive models and improved approximations of critical phenological thresholds. [ABSTRACT FROM AUTHOR]

Climate change has affected the rates of chilling and heat accumulation, which are vital for flowering and production, in temperate fruit trees, but few studies have been conducted in the cold-winter climates of East Asia. To evaluate tree responses to variation in chill and heat accumulation rates, partial least squares regression was used to correlate first flowering dates of chestnut ( Castanea mollissima Blume) and jujube ( Zizyphus jujube Mill.) in Beijing, China, with daily chill and heat accumulation between 1963 and 2008. The Dynamic Model and the Growing Degree Hour Model were used to convert daily records of minimum and maximum temperature into horticulturally meaningful metrics. Regression analyses identified the chilling and forcing periods for chestnut and jujube. The forcing periods started when half the chilling requirements were fulfilled. Over the past 50 years, heat accumulation during tree dormancy increased significantly, while chill accumulation remained relatively stable for both species. Heat accumulation was the main driver of bloom timing, with effects of variation in chill accumulation negligible in Beijing's cold-winter climate. It does not seem likely that reductions in chill will have a major effect on the studied species in Beijing in the near future. Such problems are much more likely for trees grown in locations that are substantially warmer than their native habitats, such as temperate species in the subtropics and tropics. [ABSTRACT FROM AUTHOR]

The present study investigated the genetic determinism of flowering date ( FD), dissected into chilling ( CR) and heat ( HR) requirements. Elucidation of the genetic determinism of flowering traits is crucial to anticipate the increasing of ecological misalignment of adaptative traits with novel climate conditions in most temperate-fruit species., CR and HR were evaluated over 3 yr and FD over 5 yr in an intraspecific sweet cherry ( Prunus avium) F1 progeny, and FD over 6 yr in a different F1 progeny., One quantitative trait locus ( QTL) with major effect and high stability between years of evaluation was detected for CR and FD in the same region of linkage group ( LG) 4. For HR, no stable QTL was detected. Candidate genes underlying the major QTL on LG4 were investigated and key genes were identified for CR and FD., Phenotypic dissection of FD and year repetitions allowed us to identify CR as the high heritable component of FD and a high genotype × environment interaction for HR. QTLs for CR reported in this study are the first described in this species. Our results provide a foundation for the identification of genes involved in CR and FD in sweet cherry which could be used to develop ideotypes adapted to future climatic conditions. [ABSTRACT FROM AUTHOR]

Background The reproductive phenology of perennial plants in temperate climates is largely conditioned by the duration of bud dormancy, and fruit developmental processes. Bud dormancy release and bud break depends on the perception of cumulative chilling and heat during the bud development. The objective of this work was to identify new quantitative trait loci (QTLs) associated to temperature requirements for bud dormancy release and flowering and to fruit harvest date, in a segregating population of peach. Results We have identified QTLs for nine traits related to bud dormancy, flowering and fruit harvest in an intraspecific hybrid population of peach in two locations differing in chilling time accumulation. QTLs were located in a genetic linkage map of peach based on single nucleotide polymorphism (SNP) markers for eight linkage groups (LGs) of the peach genome sequence. QTLs for chilling requirements for dormancy release and blooming clustered in seven different genomic regions that partially coincided with loci identified in previous works. The most significant QTL for chilling requirements mapped to LG1, close to the evergrowing locus. QTLs for heat requirement related traits were distributed in nine genomic regions, four of them co-localizing with QTLs for chilling requirement trait. Two major loci in LG4 and LG6 determined fruit harvest time. Conclusions We identified QTLs associated to nine traits related to the reproductive phenology in peach. A search of candidate genes for these QTLs rendered different genes related to flowering regulation, chromatin modification and hormone signalling. A better understanding of the genetic factors affecting crop phenology might help scientists and breeders to predict changes in genotype performance in a context of global climate change. [ABSTRACT FROM AUTHOR]

• PhenoFlex compiles current dormancy knowledge to predict spring phenology of trees. • Calibration with experimental data proved useful in assessing model performance. • Comparable seasons for calibration show low prediction errors of about 2 days. • Including warm seasons in model calibration increased prediction errors by 3 days. • PhenoFlex offers an opportunity to assess climate change impacts on tree phenology. Phenology models are crucial tools for assessing climate change impacts in forestry, ecology and agriculture. Such models are typically calibrated with observational or experimental data and validated with a set of independent observations. While there have been extensive discussions about validation approaches, systematic studies assessing the effects of the calibration data on the predictive performance of the fitted model are scarce. We evaluated the impact of marginal seasons in the calibration data set on the predictive power of an integrated modeling framework (PhenoFlex) that was recently proposed to predict spring phenology in temperate trees. We calibrated PhenoFlex with phenology records of apple trees from a multi-season experiment (59 experimental seasons) that included five unusually warm winter seasons. For comparison, we excluded these marginal seasons in a second version of the analysis. We fitted the 12 model parameters to data, assessed model performance using a common validation data set and evaluated the chill and heat responses during dormancy for both versions. Despite high overall accuracy, our results indicated a better model performance (Root Mean Square Errors of 2.3 versus 5.5 days) when excluding the marginal seasons. We observed a similar shape for the chill response curve across versions but a greater chill effectiveness when including the marginal seasons. Fitted parameters suggest a hard drop in heat efficiency beyond the optimum temperature when including the marginal seasons, probably highlighting the need for more moderate conditions during model calibration. Our results demonstrate a good performance of PhenoFlex when calibration and validation data were comparable, but they also indicate risks involved in using the framework to project phenology under conditions that differ strongly from those used for calibration. Further evaluation and validation under experimentally or naturally occurring warm conditions may improve our understanding of the response of temperate trees to mild winter conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Knowledge of plant-weather relationships can improve crop management, resulting in higher quality and more stable crop yields. The annual timing of spring phenophases in mid-latitudes is largely a response to temperature, and reflects the thermal conditions of previous months. The effect of air temperature on the variability of hazelnut ( Corylus avellana L.) phenophases (leafing, flowering) was investigated. Meteorological and phenological data for five cultivars were analysed over the periods 1969-1979 (P1) and 1994-2007 (P2) in Maribor, Slovenia. Phenological data series were correlated strongly to the temperature of the preceding months ( R: 0.64-0.98) and better correlated to daily maximum and mean temperatures than to daily minimum temperatures. About 75% of phenophases displayed a tendency towards earlier appearance and a shorter flowering duration during P2, which could be explained by the significant temperature changes (+0.3°C/decade) from December to April between 1969 and 2007. An increase in air temperature of 1°C caused an acceleration in leafing by 2.5-3.9 days, with flowering showing higher sensitivity since a 1°C increase promoted male flowering by 7.0-8.8 days and female flowering by 6.3-8.9 days. The average rate of phenological change per degree of warming (days earlier per +1°C) did not differ significantly between P1 and P2. An estimation of chilling accumulation under field conditions during 1993-2009, between 1 November and 28 February, showed that all four of these months contributed approximately similar amounts of accumulated chilling units. The growing degree days (GDD) to flowering were calculated by an estimated base temperature of 2°C and 1 January as a starting date, given the most accurate calculations. In general, thermal requirements were greater in P2 than in P1, although this difference was not significant. Longer-time series data extended to other agricultural and wild plants would be helpful in tracking possible future changes in phenological responses to local climate. [ABSTRACT FROM AUTHOR]

Abstract: Different chilling requirements (CRs) are required for apricot (Prunus armeniaca L.) cultivars to overcome dormancy. In a global climate change context, knowledge of these requirements is critical; producers must select the appropriate cultivars to avoid losses caused by an inadequate cultivar adaptation in a particular area. Important differences have been reported in the CRs of cultivars of temperate fruit crops that are cultivated in different climatic conditions. However, the lack of standardisation of protocols to calculate CRs hinders the comparison of the results obtained using different methodologies. This study was aimed at analysing adaptation in terms of the CR fulfilment of commercial apricot cultivars grown successfully in different climatic conditions. Apricot-growing locations with different latitudes and altitudes and cultivars with varying CRs were chosen. The plant material spanned the CR range for this species in South Africa and Spain. Three of the examined cultivars were tested simultaneously in both countries. The Utah, Dynamic and hours below 7°C models for estimating CR were evaluated and compared. The cultivars examined displayed different CR ranges in Spain and South Africa. We concluded that CR differences higher than 50% can be found for clonal plant material grown successfully in different climatic conditions. This variation might be associated both with different temperatures and other factors such as latitude. No significant differences in heat requirements were found among cultivars in Spain, suggesting that this variable might not be cultivar-specific. Finally, the distribution of clonal plant material provides an excellent framework for studying the climatic adaptation of crops. [Copyright &y& Elsevier]