Imbibition conditions and seed dormancy of Arabidopsis thaliana.

The optimal combinations of temperature in the range of 0 to 20°C and duration (1 to 14 days) of imbibition for the induction of germination of Arabidopsis thaliana (L.) Heynh., ecotype "Landsberg-erecta", by red light were investigated. At 2°C, 10 days of imbibition are needed for loss of dormancy, whereas at higher temperatures, e.g. 15°C, it is already lost after I or 2 days. It is proposed that the development of light-inducible germination is governed by two temperature-dependent processes. the loss of primary or innate dormancy and the simultaneous induction of secondary dormancy. Data are discussed in terms of the availability of phytochrome. the availability of an unknown factor X and changes in sensitivity of the process of germination induction by the far-red absorbing form of phytochrome (Pfr). [ABSTRACT FROM AUTHOR]