Relationship of the Low Temperature Exotherm to Apple and Pear Production in North America

This article gives an overview of the current state of cold hardiness research in fruit crops by reviewing the recently published studies on cold hardiness of both tree fruit and berry crops. Topics discussed include cold hardiness of fruit species, cultivars and different plant organs, biophysical and biochemical aspects of hardiness, evaluation of hardiness, as well as endogenous, cultural and environmental factors affecting cold hardiness in these species. Lack of cold hardiness is a major limiting factor for production of fruit crops in many regions of the world and improved cold hardiness one of the major objectives in numerous breeding programs and research projects. Screening cultivars or selections for cold hardiness is commonly done, and different methods applied to the evaluation of hardiness are discussed. The physical limit of deep supercooling may be a restricting factor for expanding the production of some fruit crops, such as Prunus species and pear. As for biochemical aspects, a relationship between carbohydrates and cold hardiness is most commonly found. Studies have also been made on different hardiness modifying cultural factors including rootstock, crop load, raised beds and application of growth regulators. The latter seems promising for some species. Cold hardiness is an extremely complex phenomenon and understanding different mechanisms involved is critical. Since hardiness is, however, primarily affected by genotype, developing cold-hardy fruit cultivars and effective screening methods for hardiness are essential. Finally, cultural practices may be improved to further enhance hardiness. Key words: Berries, cold hardiness, fruits, small fruits, stress, winter hardiness

Section: Cold Hardiness Of Plant Parts and Organsmentioning

confidence: 99%

Current state of cold hardiness research on fruit crops

Palonen¹,

Buszard²

1997

“…These values are close to the average monthly minimum temperatures of the 12 winter-injury years in south-western Finland: -22°C in December and -29°C in February. The mid-winter freezing resistance of apple trees varies from -30 to -40°C, fluctuating in relation to air temperature (Ketchie and Beeman 1973;Quamme 1976).…”

Section: Discussionmentioning

confidence: 99%

Re-analyzing historical records of winter injury in Finnish apple orchards

Lindén¹

2001

Lindén, L. 2001. Re-analyzing historical records of winter injury in Finnish apple orchards. Can. J. Plant Sci. 81: 479-485. Frequent winter injury is a major problem in apple (Malus domestica Borkh.) production in northern areas. Discriminant and cluster analysis were used to determine the critical climatic factors associated with winter injury occurrences in south-western Finland over a 71-yr period, 1927 to 1998. Years with and without winter injury were best characterized by variables indicating mid-winter severity: the monthly mean, minimum, and maximum temperatures from January to March. Also, weather conditions during the preceding summer and fall contributed significantly to the discrimination between winter injury and no injury years. A decrease in growing degree days, drought in August, and a high level of precipitation in September were associated with winter-kill years, probably due to their impact on the annual cycle of vegetative growth. The hypothesis on the adverse effect of mild spells during early and mid-winter could not be verified by this study. Mid-winter frost resistance was confirmed as the most important winter hardiness characteristic in the semi-maritime climate of Finland. At high latitudes rootstocks and cultural practices should be chosen to ensure that trees acquire vegetative maturity even under adverse weather conditions.

“…The degree of deep supercooling is the main factor limiting northern commercial fruit production. The temperature at which injury occurs to the most sensitive tissues is closely related to the average annual minimum isotherm temperature at the northern limits of the commercial production of apples and pears (Quamme 1976) and of the distribution of native Prunus species (Quamme et al 1982). In our study, we expressed the threat of freezing injury to tissues where deep supercooling occurs by the annual minimum temperature (AMT; Table 1).…”

Section: Cold Intensitymentioning

confidence: 99%

“…In contrast to plant parts where extracellular freezing occurs, freezing injury to these tissues will occur rapidly when the ambient temperature reaches levels below their deep supercooling point. In Pyrus and Malus species, xylem is the most susceptible tissue and the freezing resistance of cultivars grown in eastern Canada is -35°C for apple and -30°C for pear (Quamme 1976). In most of the Prunus species, flower buds are the most sensitive tissues with a LT 50 of -29 to -38°C for plum, -31°C for cultivated cherry, -22 to -26°C for apricot, and -22 to -24°C for peach (Quamme et al 1982).…”

Section: Cold Intensitymentioning

confidence: 99%

“…The fruit tree species are limited in their northern distribution to AMT isotherms that coincide with characteristics of deep supercooling of their most susceptible tissues (Quamme 1976;Pierquet et al 1977;Quamme et al 1982). The frequency of low temperature extremes and their distribution within the cold acclimation cycle of the trees should therefore be considered for the determination of plant distribution.…”

Section: Cold Intensitymentioning

confidence: 99%

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Climate change and winter damage to fruit trees in eastern Canada

Rochette¹,

Bélanger²,

Castonguay³

et al. 2004

Climatic conditions during the cold season represent a serious constraint to fruit production in eastern Canada. Meteorological models predict that temperatures of winter months will increase by 2 to 6°C by 2050. The possible impact of climate change on fruit trees in eastern Canada was assessed using agroclimatic indices expressing the risks associated with known causes of damage during fall, winter, and spring. Indices were calculated for 15 agricultural regions in eastern Canada for recent (1961–1990) and future periods (2010–2039 and 2040–2069) using temperature and precipitation data predicted by the Canadian Global General Circulation Model (CGCMI). Averaged across all agricultural regions, the first fall frost in 2040–2069 would be delayed by 16 d while the last spring frost (≤-2°C) would be advanced by 15 d. By 2040 to 2069, the risks of damage to fruit trees by early winter frosts in eastern Canada are likely to decrease because the shorter photoperiod at the time of the first fall frost would result in a longer hardening period. Milder winter temperatures will also reduce the cold stress as the accumulation of cold degree-days (<-15°C) would be reduced and the annual minimum temperature would be increased in all regions of eastern Canada. More frequent winter thaw events, however, would result in a loss of hardiness and in a thinner snow cover that would increase the plant vulnerability to subsequent extreme sub-freezing temperatures. The risk of damage to flower buds by a late frost would increase in southern Ontario, remain almost unchanged in the Maritimes and Ottawa Valley-southern Québec regions, and decrease in the Continental North. The projected climate change should allow for the introduction of new varieties and species where fruit trees are currently grown and for an extension further north of the commercial production in eastern Canada. Key words: Overwintering, fruit production, climatic indices, winter injury, spring frost