Seedbed ecology of winterfat: imbibition temperature affects post-germination growth.

Abstract

Seed imbibition is a critical first step in the awakening of an embryo plant. To determine if imbibitional conditions influenced post-germination growth, seeds of 3 winterfat (Eurotia lanata) ecotypes were imbibed at 5 temperatures from 0 to 20 degrees C, and at 5 oxygen concentrations from 0 to 40%. After a 4-day imbibition period the seeds were either dried and weighed or they were cultured in the dark at 20 degrees C. Seedling axial length was measured 5 times between 5 and 14 days post-germination to assure that maximum growth was measured. The study was repeated 3 times for each ecotype. Oxygen concentration had little effect except at 0%. As imbibition temperature increased both post-imbibition dried seed weight and seedling axil length decreased. This indicates the probability for successful termination, establishment, and survival of winterfat decreases when seeds are imbibed at 15-20 degrees C as compared to 5 degrees C. Therefore winterfat should be sown during those parts of the year when diaspores will imbibe at cool temperatures. Winterfat should be imbibed and held at 5 degrees C for 4 days, then germinated at 15 degrees C when testing germination.