Assessment of Chilling Requirement and Threshold Temperature of a Low Chill Pear (Pyrus communis L.) Germplasm in the Mediterranean Area (original) (raw)
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Flowering in temperate fruit trees depends on the temperatures during the previous months; chill is required to overcome endodormancy, and then heat exposure is needed. These agroclimatic requirements are cultivar-specific and determine their adaptability to the growing area and their response to climate change. We aim to estimate the agroclimatic requirements of 16 traditional cultivars of European pears grown in Zaragoza (Spain). We used Partial Least Squares regression analysis to relate 20-year records of flowering dates to the temperatures of the 8 previous months. This approach allowed us to establish the chilling and forcing periods, through which we quantified temperatures with three models for chill accumulation (Chilling Hours, Utah model, and Dynamic model) and one model for heat accumulation (Growing Degree Hours). The results indicated very little difference in the chilling and forcing periods. Chill requirements ranged from 43.9 to 49.2 Chill Portions; from 1027 to 116...
Chilling and heat requirements for flowering in temperate fruit trees
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 relativel...
(336) Temperature Effecton Seasonal Growth of Pear Fruit
HortScience
Temperature has long been recognized as a major environmental factor affecting the net carbon exchange in the pear tree, as well as the growth of fruit. The objective of this work was to predict pear fruit growth as a function of accumulated growing-degree-days (DD) using a mathematical model. A crop of `Abbé Fetel' trees was studied at the Experimental Farm of the Comahue National University, Argentina (lat. 38°56'S; long. 67°59'W). Maximum fruit diameter (FD) measurements were carried out every 2 weeks during three growing seasons (2000–01, 2001–-02, and 2002–03). The range of sampling dates was 26 and 143 days after full bloom (DFB). An automated meteorological station, situated close to the orchard, collected temperature data, which were expressed on the basis of DD from time of full bloom to harvest, with critical temperatures at 4 and 35 °C. Equations were developed with SYSTAT procedure and model suitability was evaluated using goodness-to-fit measures. It was fo...
Agriculture and Food, 2021
Climate anomaly has affected the rates of chilling accumulation, which are vital for flowering and production in temperate fruit trees. As an adaptation to cold winter orchards enters a period of dormancy designed to protect cold-sensitive tissues such as shoots flowers from freezing injury. Successful release from dormancy requires a specific minimum cold temperature requirement to be met for growth to resume when the temperature warms in spring. This cold temperature is specific and referred to as the "chilling requirements". The present study aimed to use the relationship between the state of chilling and the state of swelling of buds and flowering of cherry and peach for 10 stations in Bulgaria, during the period 2000-2015 and daily chill accumulation. The buds remain dormant until they have accumulated sufficient chilling units (CU) of cold weather. When enough chilling accumulates, the buds are ready to grow in response to warm temperatures. If there have been enough CU's, the flower and leaf buds develop normally. If the buds do not receive sufficient chilling temperatures during winter to completely release dormancy, trees will develop one or more of the physiological symptoms associated with insufficient chilling: 1) delayed folia appearing; 2) reduced the number of the fruits, and increased butonisation; 3) reduced fruits quality.
This research assessed the phenological response of pear (Pyrus communis L. cv. Krystalli) and of orange (Citrus sinensis L. cv. Washington Navel) trees to air temperature at the regions of Kato Lechonia in Thessaly and at Agiorgitika, Ligourio and Amycles in Peloponnesus, Greece. Phenological observations took place in order to evaluate the start dates of various phenophases of the studied cultivars, from the " end of bud swelling " to the " fruit development " stages. Also, air temperature data were monitored from meteorological stations located near the experimental orchards. The results showed that the warmer conditions at Kato Lechonia in comparison with those of Agiorgitika caused an earlier appearance of pear tree phenophases. The timing of the " end of bud swelling " at Kato Lechonia and Agiorgitika correlated negatively with the air temperature of the late winter (February) as did the timing of " bud burst " and of " appearance of flower buds " at Kato Lechonia. As regards to the orange tree, similar phenological behavior during the examined period was observed between the regions of Ligourio and Amycles due to their " similar " thermal conditions.
Plant Breeding, 2017
Dormancy release is greatly affected by chilling unit (CU) accumulation. Lack of CU has a major impact on spring vegetative budbreak (VB). To understand the genetic mechanism governing the chilling requirement (CR), we conducted a QTL analysis of VB date in F 1 population, derived from a cross between 'Spadona' (low CR) and 'Harrow Sweet' (high CR). Using a unique methodology of tree mobility, replicates of the same genotypes were exposed during the winter, over two consecutive years, to climates that differ greatly in their CU and to the same heat conditions to induce VB, in order to evaluate CR genetic impact and to distinguish it from the heat factor. Broad-sense heritability within locations ranged from 0.62 to 0.66. Due to a strong impact of GxE interaction, it was reduced to 0.46 for the overall mean. We examined the previously discovered apple QTLs detected in linkage groups (LG) 9 and 8, based on the synteny between the species. Our analysis confirms significant QTLs in LG8 (R 2 = 12%-24%) and LG9 (R 2 = 20%-38%) for all locations and years K E Y W O R D S chilling requirement, chilling units, genotype x environment interaction, linkage group, markerassisted selection 1 | INTRODUCTION Pear (genus Pyrus), part of the subfamily Amygdaloideae and belonging to the family Rosaceae, is among the three predominant fruit crops in temperate zones (Chen et al., 2014; Yamamoto & Terakami, 2016). Most of the European pear cultivars were bred in Europe and require high amount of winter chilling units for normal flowering and fruit set (Zohary, 1997). These cultivars are considered to have highquality fruit, such as 'Bartlett' and 'Bosc.' Low-chill cultivars such as 'Spadona' and 'Coscia,' which are the most commercial pear cultivars grown in Israel, are suited to warm weather but are inferior in some parameters of fruit quality (Flaishman, Amihai Shargal, & Stern, 2001; Stern et al., 2013). Dormancy is a mechanism developed by perennial plants in temperate regions to help them survive the cold winter temperatures and frost. Most Rosaceae fruit tree species enter dormancy in response to decreasing temperatures (Erez & Lavee, 1971; Horvath, Anderson, Chao, & Foley, 2003). Dormancy release is associated with the number of chilling hours (chilling units = CU) to which deciduous trees are exposed during the winter. Chilling requirements (CR) differ among cultivars and species and represent the number of CU needed for budbreak during the spring, after the tree has been exposed to favourable conditions, such as a rise in temperature, which are represented by the heat requirements (HR) (Erez & Lavee, 1971; Wigge, 2013). CR are generally characterized by the number of CU for a given cultivar to achieve 50% budbreak under favourable
Contributions of Early Season Temperatures to Pyrus Communis 'Bartlett' Fruit Growth
Acta Horticulturae, 2011
Final size of pear fruit depends on genetics, environmental and different management factors. The aim of the present study was to examine how natural temperature fluctuations affected growth of 'Bartlett' cultivar fruit. The fruit growth of 'Bartlett' pear was studied under field conditions during 2006 and 2007. Each year, ten small fruit and ten large fruit were randomly sampled and weighted from 10 different trees. Sampling began 10 days after full bloom (DAFB) until 60 DAFB with a frequency of 10 days. Total cell number and mean cell size were determined in mesocarp tissue. Mean temperatures were recorded hourly during each season. As a result of our observations, growth of 'Bartlett' pear fruit can be described by an initial exponential phase that extends for 30 days of cell division, followed by an inter-phase of cell division and cell expansion and finally a lineal phase where growth is due to cell expansion. Temperature has a major influence on fruit growth rate during the cell division phase. There was a highly significant correlation during the cell division phase between fruit growth rate (g day-1) and daily mean temperature (from 11 to16.5°C), for large fruit (R 2 =0.96) and small fruit (R 2 =0.77). Seasonal variation in final size of 'Bartlett' pear could be determined by temperature effect during cell division and resource allocation before full bloom.
The Influence of Low Temperatures During Blooming in Fruit Growing Trees Species
Current Trends in Natural Sciences, 2020
The evolution of the phenological stages of the fruit trees species is directly influenced by the climatic conditions so that the period is different from one species to another. The studies were carried out within the Research Station for Fruit Growing Iaşi, in the research fields for the main fruit tree species for the period 2018-2020. Unfavourable weather conditions during the flowering period led to damage to the viability of the buds, especially to the stone species due to the late spring frosts, which directly affected fruit production. In particular, apricots, peaches and sweet cherries suffered considerable losses. The results of the studies highlight the importance of resistance to extreme conditions of each species depending on the characteristics inherited from the biological parents.
Acta Horticulturae, 2017
A three-year study was conducted on several peach and apple cultivars respectively in order to compare two phenotyping protocols that aimed at determining the date of endodormancy break: the Tabuenca test and the single-node cutting test. The date of endodormancy release is a crucial parameter since it allows estimating the chilling and heat requirements for fruit tree flowering. The Tabuenca test was conducted during three years for 8 peach cultivars ('Sunred', 'Mayglo', 'Minastar', 'Tasty Free', 'Flavorcrest', 'Summergrand', 'Jalousia' and 'Fantasia'). The single-cutting node test was applied for two years on cultivars 'Jalousia' and 'Sunred'. For apple, both tests were applied during two years for cultivars 'Golden Delicious', 'Gala' and 'Granny Smith'. As a conclusion, for areas with insufficient chilling, it is recommended to use the single-cutting test on vegetative buds by focusing on the ATB (average time to budbreak) variable in order to select genotypes with low values during the period of forcing. On the other hand, for regions with higher heat requirement (to avoid spring frost risk), it is recommended to work on floral buds with the Tabuenca test in order to estimate precisely the dates of dormancy break and to select genotypes with higher sums of heat units.
The Survival of Pear Dormant Buds at Ultra-Low Temperatures
Plants, 2021
Currently, there is a varietal diversity decline in pear orchards of the Czech Republic. Thus, the safe storage of their gene pool collections is becoming increasingly important. Therefore, the ultra-low temperature survival after two-step cryopreservation treatment of dormant buds was tested for a safe and rapid way to conserve pear germplasm in a broader range of varieties. The following varieties crucial for cultivation in the Czech Republic were tested; ‘Amfora’, ‘Beurré Hardy’, ‘Bosc’, ‘Clapp’s Favourite’, ‘Conference’, ‘Dicolor’, ‘Erika’, ‘Lucas’, ‘Williams’ and ‘Williams Red’. In 2011 and 2012, dormant pear buds were dehydrated to 40.1% and 36.0% water content, respectively, before cryopreservation. The average regeneration of the dormant pear buds after cryopreservation by the two-step cryoprotocol in 2011 and 2012 was 54.3% and 16.1%, respectively. The mentioned cryopreservation procedure is suitable for the safe storage of dormant buds in most tested pear varieties.