Cold and Heat Tolerance

Abiotic Stress Responses in Legumes: Strategies Used to Cope with Environmental Challenges

“…Nevertheless, temperature stress is one of the primary factors limiting its growth and expansion into new regions. High temperatures can inhibit growth, reduce yield and shorten the longevity of the stand (McKenzie et al, 1988). In many alfalfa-growing areas, air temperatures may exceed 40 • C. These temperatures are considerably above the 27 • C temperatures established for optimal herbage growth.…”

“…High temperatures also increase the rate of plant development and reduce the leaf/stem ratio and digestibility in alfalfa (Buxton, 1996). Multiple biomass harvests combined with high soil temperatures can exacerbate the deleterious effects of heat stress (McKenzie et al, 1988). The reduction of forage yield in alfalfa at high temperatures (and under limited water availability) is a complex process that cannot be ascribed to a single factor.…”

“…Alfalfa genotypes selected for higher autumn dormancy also showed a positive relationship between reduced winter injury and high total soluble proteins (TSP) concentrations in alfalfa roots (Cunningham et al, 1998). The accumulation of endogenous carbon (C) and nitrogen (N) reserves in the roots of perennial alfalfa during autumn acclimation has an influence on the capacity of the plant to withstand winter stresses (McKenzie et al, 1988;Volenec et al, 2002) and the regrowth vigor during the following Spring (Dhont et al, 2006). These findings provide insights into likely mechanisms of cold acclimation and freezing tolerance in alfalfa.…”

“…Non-optimal soil conditions for crop growth include nutrient deficiencies or toxicities due to metal ions that include the presence of available aluminum (Al) ions in acidic soils. A soil pH range of 6.6 to 7.5 is ideal for alfalfa production (McKenzie et al, 1988). However, the optimum pH can vary with soil texture, organic matter and other soil chemical properties.…”

Primary Growth Parameters of Three Alfalfa Cultivars Adapted to Highland Climatic Conditions

“…Winter hardiness of alfalfa is determined by its capacity to withstand a number of environmental stressors (Belanger et al 2006) and is still a major limitation to the production of high-yielding cultivars in cold regions of northern climates despite its wide range of adaptation (Volenec et al 2002, Castonguay et al 2012. Thus, greater fall dormancy has historically been used to identify plants that are hardier in the winter because fall dormancy is closely associated with winter hardiness (McKenzie et al 1988, Sheaffer et al 1992. Plant breeders have attempted to reduce fall dormancy while maintaining winter hardiness (Volenec et al 2002).…”