Moisture Content Controls the Effectiveness of Dormancy Breakage in Abies nordmanniana (Steven) Spach Seeds

Abstract

In an attempt to overcome the lack of control of germination during traditional prechilling of Abies nordmanniana seeds, an investigation on the effect of reduced seed moisture content (m.c.) on the rate of dormancy breakage and radicle protrusion was carried out. Reduced m.c. delayed radicle protrusion and reduced the fraction of germinated seeds. At 33% m.c. fresh weight basis (f.w.) no radicle protrusion was seen even after a prolonged period at +4°C. Germination capacity (GC), and mean time to germination (MGT), were calculated from seeds prechilled at eight m.c. levels for different durations and then germinated at 25°C. Reduced m.c. resulted in a decrease in the rate of dormancy breaking, quantified as a lower increase in GC or lower reduction in MGT during the first weeks of prechilling. The critical lower m.c. threshold for dormancy breaking was around 23%. Combining the results it was concluded that prechilling of Abies nordmanniana seeds at a controlled m.c. of 33% allowed the release of dormancy in all seeds in the seedlot without any germination during the prechilling treatment. By introducing a higher degree of control the new method means improved germination capacity and an easier and more reliable dormancy breaking method.