Location: Great Basin Rangelands Research
Title: ‘Snowstorm’ forage kochia shows improved seed viability: seed size matters!Author
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Submitted to: The Progressive Rancher
Publication Type: Popular Publication Publication Acceptance Date: 4/27/2021 Publication Date: 5/10/2021 Citation: Harmon, D.N., Clements, D.D. 2021. ‘Snowstorm’ forage kochia shows improved seed viability: seed size matters!. The Progressive Rancher. 21(5):16-18. Interpretive Summary: Technical Abstract: Big sagebrush (Artemisia tridentata) is not a fire-tolerant species. Big sagebrush does not resprout after fire and often must be restored through seeding or transplanting efforts. In higher elevations dominated by mountain big sagebrush (Artemisia tridentata subsp. vaseyana), the cooler, wetter climate significantly improves successful seeding efforts. In contrast, the more arid climate of the lower elevation Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) habitat makes successful seeding efforts very difficult. The high percentage of failure for sagebrush seeding efforts makes the need for a dependably seeded shrub species extremely important. A well adapted shrub species to mitigate sagebrush loss is forage kochia (Kochia prostrata). Forage kochia is a long-lived, semi-evergreen perennial subshrub native to the arid and semiarid regions of southern Eurasia. It has been seeded on thousands of acres of semiarid rangelands of the Intermountain West for reclamation, fire breaks, and wildlife and livestock forage. Though its use can spark controversy, there is no doubt it has performed well for its intended purpose: to compete, establish and persist with invasive annuals such as cheatgrass in arid environments. Forage kochia reduces fires, erosion and weeds while providing a much-needed forage resource as well as structural shrub component to the plant community. The biggest challenges that managers face using forage kochia are the timing of seed production and the ability of forage kochia seed to maintain viability beyond the initial seed production year. Forage kochia seeds ripen in October and are often harvested October through January, though newly harvested and processed seed may not be available until after December, making seeding at the optimal time in the fall and early winter difficult with the current year’s seed availability being very limited. There are two cultivars of forage kochia available for use, the earlier release (1986) ‘Immigrant’ (Kochia prostrata subsp. virescens) and the more recent release (2012) ‘Snowstorm’ (Kochia prostrata subsp. grisea). ‘Immigrant’ forage kochia seed can lose viability rapidly if it is not kept in cold storage. This means that seeding in the fall, at the optimal timing for success, requires using 1-year-old cold-storage seed from the previous year’s harvest or using warehouse-stored seed with lower viability and increasing the seeding rate. In 2018 the USDA-Agricultural Research Service, Great Basin Rangelands Research Unit, in Reno, Nevada began a study examining the viability of ‘Immigrant’ and ‘Snowstorm’ forage kochia seed stored in air-tight Ziplock bags in cold storage 0°C (32°F), in typical warehouse (shed) conditions and at a constant room temperature 20°C (68°F). We used germination as an analog for seed viability as there is typically little seed dormancy with forage kochia, leading to most viable seeds germinating. In general, ‘Snowstorm’ seed had more reliable germination among collections prior to storage. ). ‘Immigrant’ forage kochia, as previously observed, did lose viability after 1 year of storage in all storage conditions. Surprisingly, though, after 1 year, cold storage showed no improvement over warehouse (shed) storage for ‘Immigrant’ forage kochia . However, after 2 years of storage, cold storage was required to maintain seed viability for ‘Immigrant’ forage kochia. Even more surprisingly, ‘Snowstorm’ had increased germination after 1 year in cold and warehouse storage conditions. These results have important range rehabilitation implications. Being able to use warehouse stored ‘Snowstorm’ forage kochia seed at a lower cost so that seeding can be done at the optimal time in the fall will increase the chance of seeding success. Being able to store seed and maintain viabilty will also improve the availability of seed for catastophic wildfire yea |
