Increasing pre-acclimation temperature reduces the freezing tolerance of winter-type faba bean (Vicia faba L.)

Autumn-sown winter-type faba bean (Vicia faba L.) has been shown to have a yield advantage over spring sowing. Still, adoption of this overwintered pulse crop remains limited in temperate locations, due to inadequate winter hardiness. This research sought to understand how the prevailing temperature during emergence and seedling development, that is pre-acclimation, influences freezing tolerance. Seedlings grown under a controlled warm 17/12 degrees C (day/night) pre-acclimation environment were initially less freezing tolerant than those grown under a cold 12/5 degrees C temperature treatment. Stem and particularly root tissues were primarily responsible for slower cold acclimation, and there was a genotype specific response of above-ground tissues to pre-acclimation treatment. Both above and below-ground tissues should be tested across a range of pre-acclimation temperatures when screening faba bean germplasm for freezing tolerance.