A New Composition for Solid Matrix Priming of Seed

Seed priming is a technique that improves germination percentage, rate of germination, germination uniformity, and/or stand establishment.  During a priming protocol, physiological processes are initiated but radicle emergence is prevented by altering surrounding osmotic (osmotic priming) or matric (solid matrix priming) potential.  In the present study, a novel composition of arboretum and greenhouse waste compost and hydrogel plus distilled water was used for solid matrix priming.  Processed and sieved arboretum and greenhouse waste compost was combined with fine-grade hydrogel (SuperSorb∙F; Aquatrols Corp., Paulsburo, NJ) and distilled water to obtain a seed priming composition that was flowable with high moisture content (115% to 228%, dry weight basis) generating water potentials of –1.6 to –0.5 MPa.  The composition exhibited negligible osmotic potential and maintained matric potential of –1.0 MPa throughout 7 d priming of carrot (Daucus carota L.) seed incubated at 15 °C.  Solid matrix priming increased germination rate (time to 50% germination) of carrot by up 74% but this was dependent on cultivar type and ratio of seed-to-priming component.  Benefits of solid matrix priming using compost and hydrogel versus osmotic priming using polyethylene glycol include enhanced uniformity of water potential during the procedure and less chemical disposal issues.  Its renewable nature distinguishes it from other solid matrix priming materials and, specifically, the ability to generate sufficiently high water content at appropriate matric potentials distinguishes the new composition from other compost priming methods.