Accroissement de la résistance au froid de plantules de blé avec un milieu cryoprotecteur : variation de la température et de la durée du traitement d'imprégnation. Aspects physiologiques

Abstract

Different methods of hardening wheat seedlings to withstand freezing to low temperatures were studied. The procedures involved the impregnation of the seedlings with a cryoprotective mixture of glycerol, dimethyl sulfoxide and sucrose for various times and at various temperatures. Impregnation of the seedlings with such a mixture at 20 °C for 1 day imparted an effective protection to freezing at 1 °C/min. Longer periods of impregnation did not further increase the freezing survival. On the other hand, if the impregnation was carried out at 2 °C, freezing tolerance developed only slowly for the first 3 days, but improved rapidly between the 4th and the 6th day. Longer periods of impregnation at 2 °C did not further increase freezing survival. Freezing tolerance was observed to be related to both a lowered nucleation and ice-formation temperature in the impregnated tissues.