Effect of solid matrix priming during moist chilling on dormancy breakage and germination of seeds of four fir species

摘要

The ability of solid matrix priming (SMP) to overcome seed dormancy of seeds of four fir species (Pacific silver fir, subalpine fir, grand fir and noble fir), was examined. Seeds were subjected to treatments that combined moist chilling and SMP (SMP-chilling) and their germination compared to that elicited by traditional moist chilling. For the SMP-chilling, six solid matrices with different water holding capacities were tested (sphagnum, cat litter, peat moss, Agro-Lig Greens Grade, Agro-Lig Micro Fine and sand). For each of the species tested, germination performance was significantly improved by SMP-chilling; the results were dependent on the type of solid matrix, the matrix water content and the treatment duration. SMP-chilling, using the best solid matrices for each of the species tested, resulted in germination percentages and rates that were 24-35% and 8-21% higher, respectively, as compared with that yielded from control moist-chilling. High germination percentages (79% or greater) of three of the four species (Pacific silver fir, subalpine fir, and grand fir) were promoted after just four weeks (grand fir in sand) or eight weeks of treatment (Pacific silver fir in peat moss and subalpine fir in Agro-Lig Greens Grade). The germination rate of grand fir seeds benefited from SMP-chilling periods longer than four weeks, but this resulted in germination during the dormancy-breaking treatment. The water contents of the solid matrices that were optimal in terms of eliciting the best germination performance were 320% (w/w) for peat moss, 40% for Agro-Lig Greens Grade and 5-15% for sand. Conducting SMP at chilling temperatures (4 degreesC) is a practical approach to shorten the time required for effective dormancy termination of Abies seeds; treatment times were shortened by 27 days for Pacific silver fir and subalpine fir and more vigorous seedling growth was exhibited by grand fir and noble fir.