Freezing Tolerance Attributes during Spring Deacclimation for Three Asparagus Cultivars with Varying Adaptation to Southern Ontario

Abstract

<jats:p>Winterhardiness in asparagus (<jats:italic>Asparagus officinalis</jats:italic>) may be related to proper cold acclimation and induction of freezing tolerance in the fall, levels and maintenance of freezing tolerance in the winter, and the timing of deacclimation in the spring. Premature deacclimation and the inability to reacclimate could result in crown damage from spring freeze-thaw cycles. A field experiment was conducted, replicated over 2 years, to determine how three cultivars with varying adaptation to southern Ontario deacclimate in the spring by assessing LT<jats:sub>50</jats:sub> (the temperature at which 50% of plants die) and biochemical and physiological parameters associated with freezing tolerance. ‘UC 157’ (UC), the least-adapted cultivar, deacclimated after soil temperatures rose above freezing; LT<jats:sub>50</jats:sub> values increased linearly over time and were unaffected by fluctuations in soil temperature. ‘Jersey Giant’ (JG), a cultivar with moderate adaptation, rapidly deacclimated with increased soil temperature but appeared to partially reacclimate as temperatures decreased. For ‘Guelph Millennium’ (GM), the most-adapted cultivar, LT<jats:sub>50</jats:sub> values did not change, maintaining the greatest levels of freezing tolerance during the spring sampling period. Although LT<jats:sub>50</jats:sub> values did not differ among cultivars on the first spring sampling date, ranking for freezing tolerance at the final sampling in each year was GM&gt;JG&gt;UC, which is consistent with adaptation. Rhizome traits were most associated with freezing tolerance and included high concentrations of low-molecular-weight fructans (LFs), glucose, and proline and low percentage water and sucrose concentration. Overall, data suggest that the timing of deacclimation and loss of freezing tolerance in the spring may significantly affect winterhardiness; cultivars that lose freezing tolerance early and cannot reacclimate could suffer most from late spring freeze-thaw cycles.</jats:p>

Metabolomic changes in crown of alfalfa (Medicago sativa L.) during de-acclimation

“…Although there is no consensus regarding the relationship between the plant tissue water content and cold hardiness, most researchers believe that cold hardiness is negatively associated with increasing water content due to lower water content can decreased osmotic pressure 5 , 7 , 8 , 42 . In this study, an analysis of acclimation revealed that the freezing tolerance of alfalfa was highest in phase 3 because of its decreased water content and freezing conditions (Fig.…”

“…A series of physiological, biochemical, and molecular changes induced by photoperiod and temperature maximize the freezing tolerance of plants during acclimation 3 – 5 . Earlier research indicated that the hardiness of perennial ryegrass ( Lolium perenne L.) 6 and asparagus ( Asparagus officinalis L.) 7 , 8 is negatively associated with increasing water contents. A decrease in the water content can lower the freezing point of cells, whereas an increase in the water content may result in mechanical damages due to extracellular freezing as well as an increase in the ice propagation rate in tissues 7 – 9 .…”

“…Earlier research indicated that the hardiness of perennial ryegrass ( Lolium perenne L.) 6 and asparagus ( Asparagus officinalis L.) 7 , 8 is negatively associated with increasing water contents. A decrease in the water content can lower the freezing point of cells, whereas an increase in the water content may result in mechanical damages due to extracellular freezing as well as an increase in the ice propagation rate in tissues 7 – 9 . Furthermore, the “energy-competitive hypothesis” states that the allocation of substances during acclimation will affect the freezing tolerance of plants, with a decrease in metabolizable energy consumption and an increase in energy production conducive to low-temperature stress tolerance when the water content is low 5 .…”

Drip Irrigation Depth Alters Root Morphology and Architecture and Cold Resistance of Alfalfa

“…Carbohydrates not only act as osmotic regulators to protect the integrity of cell structure and function, but are also intracellular signaling molecules that regulate gene expression during plant growth and development, and are strongly associated with plant cold resistance [45,46]. Increase in the contents of total soluble sugars, sucrose, glucose, fructose, and trehalose in cells is beneficial to improve the cold resistance of plants [8,45,47,48]. In the current study, surface drip irrigation (Deep-0) was more conducive to accumulation of soluble sugars, sucrose, glucose, and fructose in the root crown, whereas trehalose content showed no significant difference among the treatments, which was consistent with the trend in change of LT 50 .…”