Influence of Soil Moisture on Cold Tolerance of Alfalfa

R. 2006. Winter damage to perennial forage crops in eastern Canada: Causes, mitigation, and prediction. Can. J. Plant Sci. 86: 33-47. Harsh winter climate results in frequent losses of stands and yield reduction in many forage-growing areas of Canada and other parts of the world. Climatic conditions and crop management both affect the winter survival of perennial forage crops. In this review, we present the main causes of winter damage in eastern Canada and we discuss crop management practices that help mitigate the risks of losses. Predictive tools available to assess the risks of winter damage both spatially and temporally are also presented. Our understanding of the causes of winter damage and of the plant adaptation mechanisms to winter stresses, particularly the role of N and C organic reserves, has improved. Forage species commonly grown in eastern Canada differ in their tolerance to subfreezing temperatures and to anoxia caused by the presence of ice on fields. Some improvement in winter hardiness of forage legume species has been achieved through breeding in eastern Canada but new technologies based on laboratory freezing tests and the identification of molecular markers may facilitate the future development of winter-hardy cultivars. Crop management practices required for good winter survival are now better defined, particularly those involving cutting management and the interval between harvests. Simulation models and climatic indices derived from our current knowledge of the causes of winter damage provide general indications on the risk of winter damage but their degree of precision and accuracy is still not satisfactory. Further improvements in winter survival require a more thorough understanding of the different causes of winter damage and, primarily, of their complex interactions with genetic, climatic, and management factors.

Section: Exposure To Subfreezing Temperaturesmentioning

confidence: 99%

mentioning

confidence: 99%

Winter damage to perennial forage crops in eastern Canada: Causes, mitigation, and prediction

Bélanger¹,

Castonguay²,

Bertrand³

et al. 2006

“…For example, cold-acclimated alfalfa (Medicago sativa L.), an herbaceous forage species of intermediate hardiness that tolerates extracellular freezing and experiences freeze-induced cell desiccation, can withstand temperatures as low as -20 to -26°C for a brief period (few hours) but is damaged if exposure to milder temperatures of -8 to -10°C is extended for a few days (Paquin 1984). Accordingly, maximum cold tolerance of alfalfa under field conditions, expressed by LT 50 or the temperature at which 50% of plants are killed, rarely goes below -15°C in the different climatic zones in Québec (Paquin and Mehuis 1980).…”

Section: Cold Intensity and Durationmentioning

confidence: 99%

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

“…The freezing test was carried out according to Paquin and Mehuys (1980). Plants taken out from the freezing room at 3-h intervals were kept at l-2"C for 12 -24 h and then transferred to a growth area.…”

Section: Plant Growthmentioning

confidence: 99%

Evolution of Polyamines in Winter Cereal and Forage Species Under Field Cold Acclimation in Quebec

Nadeau¹,

Paquin²

1988