Extruded seed pellets: a novel approach for enhancing sagebrush seedling emergence

Abstract

Small or low-vigor species can be susceptible to being planted at depths that prevent seedling emergence. As an example, sagebrush (Artemisia spp. L. [Anthemideae]) seed is often prone to being planted at depths where the seedlings cannot emerge from the soil. We evaluated a potential solution to this problem that incorporates seed within an extruded pellet that is designed to enhance seedling emergence through the swelling action of the pellet creating conduits for the emerging seedlings to follow. We quantified the swelling capacity of the extruded pellet and evaluated how the technology improves seedling emergence and plant growth of Wyoming big sagebrush (Artemisia tridentate Nutt. ssp. wyomingensis Beetle & Young), over a range of seeding depths (5, 10, and 15 mm [0.2, 0.4, and 0.6 in]), within silt-loam and sandy-loam soils. Swelling capacity of the pellets in the silt-loam soil was approximately twice that of the sandy-loam soil. At all planting depths, pellets improved seedling emergence between 2.3- to 10.0-fold in the silt-loam soil. In the sandy-loam soil, no treatment effect occurred for seedling emergence at the 5 mm and 15 mm depths, but pellets enhanced emergence at the 10 mm depth by 3.1-fold. Some indications suggest that seedlings produced from the extruded pellets had greater growth than untreated seed. This technology opens up the possibility for sagebrush (and potentially other small-seeded species) to be seeded at deeper soil depths where soil water potential levels are more conducive for seed germination and seedling survival. Future development and field testing are merited.