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

Abstract

The ability of solid matrix priming (SMP) to overcome seed dormancy ofseeds of four fir species (Pacific silver fir, subalpine fir, grand fir andnoble fir), was examined. Seeds were subjected to treatments that combinedmoistchilling and SMP (SMP-chilling) and their germination compared to that elicitedby traditional moist chilling. For the SMP-chilling, six solid matrices withdifferent water holding capacities were tested (sphagnum, cat litter, peatmoss,Agro-Lig Greens Grade, Agro-Lig Micro Fine and sand). For each of the speciestested, germination performance was significantly improved by SMP-chilling; theresults were dependent on the type of solid matrix, the matrix water contentandthe treatment duration. SMP-chilling, using the best solid matrices for each ofthe species tested, resulted in germination percentages and rates that were24–35% and 8–21% higher, respectively, as compared with thatyieldedfrom control moist-chilling. High germination percentages (79% or greater) ofthree 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 oftreatment (Pacific silver fir in peat moss and subalpine fir in Agro-Lig GreensGrade). The germination rate of grand fir seeds benefited from SMP-chillingperiods longer than four weeks, but this resulted in germination during thedormancy-breaking treatment. The water contents of the solid matrices that wereoptimal 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 °C) is a practicalapproach to shorten the time required for effective dormancy termination ofAbies seeds; treatment times were shortened by 27 days forPacific silver fir and subalpine fir and more vigorous seedling growth wasexhibited by grand fir and noble fir.