Evaluation of freezing tolerance of whole plants in komatsuna (Brassica campestris L.) and spinach (Spinacia oleracea L.).

摘要

To establish a practical method to evaluate the frost tolerance of leafy vegetables, the relationship between freezing tolerance of intact komatsuna and spinach plants, cold-acclimated at different temperatures and electrolyte leakage from leaf tissues was determined. In both komatsuna and spinach, the frost tolerance correlated well with electrolyte leakage from leaf tissues, especially with the leaf area that was damaged by freezing during cold acclimation (i.e, high, middle and low temperature treatments). However, the temperature at which 50% electrolyte leakage from tissues occurs (TEL50) was consistently lower by 2-4deg C than the temperature at which 50% of leaf area was injured. When frost tolerance as determined by the electrolyte leakage from leaf tissues was compared with that of the whole plant, at TEL50 almost all leaves were severely injured and recovery of plant growth was substantially delayed. The frost tolerance of whole plants of komatsuna and spinach may best be expressed as theTEL15 or TEL20 (at which temperature only 15-20% of the electrolytes leak from leaf tissues). The maximum of 100% electrolyte leakage is obtained from ground tissues or tissues subjected to a freeze/thaw cycle to -80deg C.