Preparing sagebrush seed for market: effects of debearder processing.

Abstract

Debearders are machines originally developed to remove grain from bearded (awned) seed heads of small grains. They are now used in many types of seed cleaning, including preparing sagebrush seed for market. Some people have suggested that debearders may decrease sagebrush seed quality. We tested this hypothesis by using a debearder to process seeds of Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis) and measuring subsequent seed quality. Seed stalks were cut from 2 Wyoming locations, stored in an unheated warehouse, and then processed with a debearder for 2, 4, 6, 8, or 10 min. Seed germination and seedling vigor were tested at 2-month intervals up to 16.5 months after processing. Temperature and relative humidity inside the debearder increased linearly from 14.0 to 22.4 degrees C and from 59.0 to 81.2 % during the 10-min. processing time. However, the moisture content of seed materials did not change during this period. The number of undamaged seeds per gram of material did not change with processing and was similar between collections. Stem length decreased with processing duration while percent of seed with pericarp removed increased. Germination percentage, time to 50 % germination (T50) and seedling vigor were similar among treatments in both collections. Germination percentage increased in the first 4.5 months after processing and then remained at that level up to 16.5 months. Germination rate decreased (T50 increased), but seedling vigor did not change with storage time. We recommend that seed dealers continue to use properly adjusted debearders to process sagebrush seed.