Abstract —This study examines three myths of sagebrush ( Artemisia spp.) seed technology. These myths are: (1) processing sagebrush inflorescences through a debearder will lower seed viability; (2) seeds of sagebrush cannot be cleaned economically beyond 12 percent purity; and (3) sagebrush achenes (seeds plus pericarps) retain viability longer than sagebrush seeds (achenes with pericarps removed). Evidence given in this paper support the conclusion that all three myths are false.
This paper explores the truthfulness of three myths of sagebrush seed technology. A myth is “a belief given uncritical acceptance by the members of a group, especially in support of existing or traditional practices.” The myths referred to are: (1) processing sagebrush inflorescences through a debearder will lower seed viability; (2) seeds of sagebrush cannot be economically cleaned beyond 12 percent purity; and (3) sagebrush achenes (seeds plus pericarps) retain viability longer than sagebrush seeds
(achenes without pericarps). Hypotheses tested are: viability of sagebrush seeds passed through a debearder is equal to the viability of seeds not passed through a debearder; sagebrush seed can be cleaned economically beyond 12 percent purity; and viability of stored sagebrush seeds is equal to the viability of stored achenes.
Five experiments were conducted to obtain the data presented in this study. Each experiment is outlined below.
This experiment was designed to determine if passing sagebrush inflorescences through a debearder lowers seed viability. Inflorescences were obtained from a native
Wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis ) stand, clipped by hand, and dried to a moisture content of about 13 percent. Drying was accomplished using a forced air heater. The heater circulated dry air around and through the pile of inflorescences. Temperature of the air contacting the inflorescences never exceeded 32 ° C.
Main stems were removed and the resulting mixture of achenes, seeds, seed bracts, leaves, and fine stems were placed in 30-gal plastic garbage cans. Samples were taken
In: Roundy, Bruce A.; McArthur, E. Durant; Haley, Jennifer S.; Mann,
David K., comps. 1995. Proceedings: wildland shrub and arid land restoration symposium; 1993 October 19-21; Las Vegas, NV. Gen. Tech.
Rep. INT-GTR-315. Ogden, UT: U.S. Department of Agriculture, Forest
Service, Intermountain Research Station.
Bruce L. Welch is Principal Research Plant Physiologist, Shrub Sciences Laboratory, Intermountain Research Station, Forest Service, U.S.
Department of Agriculture, Provo, UT 84606.
126 from each garbage can before the contents were run through a “Cripen Model DB-1524” debearder. Samples were taken of the material after it passed through the debearder. After cleaning to a purity of 56.7 percent (see experiment 3 for cleaning details), achenes, seeds, and trash were passed through the debearder a second time and samples taken. This yielded three treatments: no passage through the debearder, single passage through the debearder, and after cleaning, a second pass through the debearder. Each treatment was represented by six replications of 100 achenes or seeds. Also, the percentage of achenes per treatment was noted as an indicator of harshness of treatment. The lower the percentage of achenes the harsher the treatment.
Viability was determined by using the tetrazolium staining test (Grabe 1972) as outlined by Meyer and others 1987. “Tetrazolium viability was determined by piercing imbibed seeds (seeds setting 24 hours on a saturated filter pad inside of a petri dish) with a fine needle through the center of the cotyledon region of the embryo, immersing the seed in 1 percent buffered tetrazolium chloride solution for 6 hours (I saturated the filter pad with 1 to
2 ml of 1 percent buffered tetrazolium chloride solution and allowed the seeds to set on the pad for 24 hours) at ca. 25c, slitting the cotyledon end of the pericarp and seed coat with a needle, and squeezing out the intact embryos.
Embryos stained a uniform bright red were classed as viable” (Meyer and others 1987).
Data, from the three treatments, were statistically analyzed ( P < 0.05) by means of a one-way analysis of variance. For significant F tests, Newman-Keuls’ multiple range tests were used to test for significant differences among treatment means.
The objective for this experiment was the same as that outlined for experiment 1. Biological material for this experiment came from a ‘Hobble Creek’ (Welch and others
1986) mountain big sagebrush ( A . t . ssp. vaseyana ) seed increase garden. This experiment was conducted in the same manner as experiment 1, with the following exception: when the seeds, achenes, and chaff were run the second time through the debearder the exit door was tied so that the material could exit only a small opening (about
10 percent of the usual opening). Materials run through the debearder a second time were warm to the touch. This treatment exposed the seeds to the maximum harshness in the debearder.
This experiment was designed to show that sagebrush seed can be cleaned economically beyond 12 percent purity. Biological material for this experiment came from

a ‘Hobble Creek’ mountain big sagebrush seed increase garden. Inflorescences were removed by hand then dried by a forced air heater to a moisture content of 12 percent.
Main stems were removed and the resulting mixture of seeds, seed bracts, leaves, and fine stems were placed in 30-gal plastic garbage cans. Next, the content of the garbage cans were fed through a debearder set up as described in experiment 1. Then the material was cleaned by a two-screened Crippen model XV-242-LH seed cleaner with air lift. A 14-by-14 mesh screen was placed in the top screen position with a 36-by-36 mesh screen in the bottom position. Air lift was adjusted to maximum lift without picking up seeds. Weights were taken of all materials (seeds, seeds bracts, fine stems) that were passed through the debearder, carried over the 14-by-14 mesh screen, passed through the 36-by-36 mesh screen, and uplifted by the air lift. Materials carried over the 14-by-14 mesh screen, uplifted by air lift and passed through the
36-by-36 mesh screen were considered screenings and would normally be discarded. Materials passing through the 14-by-14 mesh screen, carried over the 36-by-36 mesh screen and not uplifted would be either the final product of cleaned seed or the materials used for reruns through the seed cleaner to obtain higher degrees of purity.
This experiment had the same objective as experiment 3.
After finishing experiment 3, I found that the starting seed purity of the biological material was 13.2 percent.
This was unusually high for a field seed lot. I felt that
I needed to test the cleaning procedure on field seed lots with lower starting purity. Three field seed lots with starting seed purity of 6.1, 7.5, and 9.4 percent were located and run through the debearder once and the seed cleaner four times.
Because passing sagebrush seed through a debearder and a seed cleaner removes all of the pericarp from some of the sagebrush achenes, this experiment was designed to test the hypothesis that seeds in intact achenes retained higher viability in storage than seeds out of achenes. Biological material was obtained from ‘Hobble
Creek’ mountain big sagebrush seed stored at the Shrub
Sciences Laboratory in paper envelopes. Age of the seeds was 52, 76, and 88 months. Samples from each age group were separated into achenes with fully intact pericarps and seeds outside achenes (pericarps were removed).
Tests included six replications of 100 achenes and 100 seeds per age group. Seed viability was determined for the two classes as outlined in experiment 1. Data were statistically analyzed by means of student’s tests of unpaired observations ( P < 0.05) for each age group.
Results of experiments 1 and 2 are given in table 1.
There were no significant differences in seed viability between seeds passed through the debearder once or twice
Table 1 —Effects of debearder on sagebrush seed viability and percent of seeds outside achenes. Data expressed as a percent of live seeds for seed viability and percent of seeds outside achenes. Means and standard deviations sharing the same superscripts in columns of the same experiment are not significantly different ( P < 0.05)
Percent of viable seeds
Percent of seed outside achenes
Experiment 1
Before debearder
After 1st debearder
After 2nd debearder and cleaning
Experiment 2
Before debearder
After 1st debearder
After 2nd debearder and cleaning 1
1 Exit door tied nearly closed.
93.3
± 1.79
a
93.0
± 1.87
a
93.0
± 0.71
a
87.8
± 3.11
a
89.0
± 3.74
a
40.8
± 8.26
b
18.0
± 3.08
a
48.3
± 4.76
b
66.8
± 1.79
c
2.3
± 1.48
a
20.3
± 5.76
b
79.3
± 2.28
c or not at all. There was a significant increase in the percentage of seeds outside the achenes with repeated runs through the debearder. For experiment 2, there were no significant differences in seed viability between seeds before debearding and those run through the debearder once; however, with the second run through the debearder
(with exit door tied nearly closed) seed viability dropped significantly. As with experiment 1, number of seeds outside the achenes increased significantly with the second run through the debearder. What these data sets tell us is that sagebrush seed can be put through a properly adjusted debearder without affecting seed viability. However, as shown in experiment 2, an improperly adjusted debearder will greatly reduce seed viability. Welch and others (1986) warned that this procedure “should be done rapidly so that seeds are not overheated.” Shaw and
Monsen (1990) reported the use of debearders to facilitate sagebrush seed cleaning. Variables that need to be watched include: length of debearder, pressure on exit door, and rotational speed of debearder.
Results of experiment 3 are given in figure 1. Final product, after five runs through the seed cleaner, weighed
17.56 pounds with a purity of 65.9 percent. Seed viability as determined by the tetrazolium test was 93 percent. At four runs through the seed cleaner the purity was 53.3
percent. These purities are well above the 8 to 12 percent standards set in the literature (Steven and Meyer 1990).
By pouring the 17.56 pounds of final product of experiment 3 in front of a greenhouse exhaust fan, I obtained a product that had a purity of 89.1 percent. I did experience a seed loss of 1.5 percent using this technique.
For runs III, IV, and V the purity of the materials carried over the 14-by-14 mesh screen was: 10.6, 17.6, and
15.8 percent, respectively. The producer may choose to rerun these lots through the seed cleaner and clean them up to at least 50 percent purity. About 80 percent of the seed can be recovered. The producer also can save the lots and sell them to an agency with lower standards.
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Figure 1 —A flow chart outlining the movement of a big sagebrush seed lot, weighing 107.35
pounds, through an air/screen seed cleaner.
Before cleaning, the seed lot was passed through a debearder. Trash was separated from seeds by being carried over the 14-by-14 mesh screen, being air lifted from the seed, passing through the 36-by-36 mesh screen, or being lost as flying dust. The final product was obtained by running the material carried off the
36-by-36 mesh screen five times through the seed cleaner. Final product had a purity of
65.9 percent and a seed viability of 93 percent.
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I did not realize when conducting this experiment that the material I was using had a starting purity of 13.2 percent.
Experiment 4 was conducted to see if materials with lower percentages of purity could be cleaned to 50 percent or greater. Results were similar to those of experiment 3.
After four runs through the seed cleaner, the lot that started at 6.1 percent purity was cleaned to 51.8 percent, the 7.5 percent purity lot was cleaned to 51.2 percent, and the 9.4 percent purity lot was cleaned to 58.7 percent.
Dean Swift (1993) reported that by using a combination of air/screen cleaners and a gravity table he can clean A .
frigida seed to 98 percent purity and above. A . frigida seed is smaller than the seed of big sagebrush. Further,
Welch and others (1986) suggested the possibility of cleaning ‘Hobble Creek’ mountain big sagebrush ( A . t . ssp.
vaseyana ) to 95 percent purity with present-day technology. Shaw and Monsen (1990) reported seed dealers
“cleaning sagebrush seed lots to purities of 20 to 40 percent,” with some as high as 80 percent. Neither report commented on the economics of seed cleaning.
Cleaning costs are about $0.50 to $1.00 per pound of pure live seed (pls). The seed cleaner I used in the study is not a high capacity cleaner, but costs did not exceed
$1.00 per pound of pure live seed (pls). Higher capacity cleaners should cut cleaning costs significantly. I believe it is reasonable for the consumer to demand a purity of at least 50 percent. Higher purities are obtainable by combining the air/screen cleaner with other cleaning machines, such as a gravity table (Swift 1993). Cost of cleaning should be offset by the savings in handling less bulk.
The cost of the seed should not increase.
Savings from higher purities occur at every stage of handling. This includes sacking, transporting to buyer sites, storage, transportation to planting sites, and amount of land seeded per filling of planting hoppers. To illustrate these savings, I will compare two sales. Both sales are for 1,000 pounds pls of Gordon Creek Wyoming big sagebrush seed (Welch and others 1992). Sale number 1 seed lot has a purity of 50 percent with 80 percent viability. Sale number 2 seed lot has a purity of 12 percent with 80 percent viability.
I estimated from seed lots on hand at the Shrub Sciences
Laboratory that 1 cubic foot of seed and trash from sale 1 weighs about 17 pounds, from sale 2 about 10 pounds.
Sacks 25 by 36 inches provide about 4 cubic feet of space.
Sale 1 sacks would weigh 68 pounds; sale 2 sacks would weigh 40 pounds. Sale 1 would be sacking 2,500 pounds total of seed and trash to obtain the 1,000 pounds pls; this would require 37 sacks. However, 260 sacks would be required for sale 2. Sale 1 would result in saving 223 sacks or $111 plus the labor it takes to fill, sew, and handle the additional 223 sacks. Sale 1 could be stored in about 148 cubic feet of space at a cost of $4.44 per month. Storage costs for sale 2’s 1,040 cubic feet would be about $31.00
per month. (Storage costs are about 3 cents per cubic foot per month.) Sale 1 would save $26.56 per month on storage over sale 2. Shipping costs (from Lindon, UT to Boise,
ID-freight class 100) of sale 1’s 2,500 pounds (68 pounds

per sack x 37 sacks) would be $489.00; sale 2’s 10,417 pounds would cost $1,577.00. Again a savings of about
$977.00. Total savings at the higher purity would be:
Sacks saved ------------------------------------------------$111
Labor saved by handling fewer sacks --------------?
Shipping cost saving -------------------------------------$1,078
Storage cost saving --------------------------------------$27+
Total savings (at least) ------------------------------- $1,176+
All these savings are from the producer end and should either earn the producer more money or offset the cleaning cost.
The buyer would experience savings by handling less trash. Further savings would occur in storage (6.9 times more costly for sale 2), transportation to seeding sites (3.1
times more costly for sale 2), and in the planting process.
A seeding contractor estimated savings of 20 percent in seeding cost by using sale 1’s seed instead of sale 2’s seed
(Johansen 1993). I believe the estimated savings to be low. The contractor used the figure of 12 pounds per cubic foot for 40 percent pls (50 percent purity times 80 percent viability) for his estimates. My measurement for 40 percent pls (9.3 percent moisture) was 17.2 pounds per cubic foot. If my measurements are correct, this means about a 43 percent increase in the amount of seed that can be carried per load. At any rate, significant savings can be achieved by seeding with seed lots of higher purity.
One additional benefit of cleaning big sagebrush seeds to higher percents of purity is human health. I found handling sacks of seed cleaned beyond 12 percent purity produced far less dust.
Results of experiment 5 are given below. As shown, there is no significant difference in seed viability between seeds in intact achenes and seeds outside the achenes, regardless of age of the seed.
Age of seeds Seeds in intact achenes Seeds outside achenes
Months - - - - - - - - - - - - - - - -Percent - - - - - - - - - - - - - - - -
52
76
88
91.0 ± 2.35
56.0 ± 5.39
40.0 ± 1.58
90.3 ± 1.09
58.0 ± 6.16
44.0 ± 3.08
The five experiments outlined in this paper conclusively indicate that the three myths examined in this study concerning sagebrush seed technology are false. Modern technology allows us to clean and sort seeds to high levels of purity quite economically, and to provide seeds of high viability whether the achene has been removed or not.
The author expresses his gratitude to the following individuals for their assistance and encouragement during the course of this study: Warren T. Bell, Terry Booth, Don
Heslop, James H. Johansen, Susan E. Meyer, David L.
Nelson, Alan R. Sands, Nancy L. Shaw, Dean Swift, and
Fred J. Wagstaff.
Grabe, D. L. 1972. Tetrazolium testing handbook for agricultural seeds. Contribution 29, handbook on seed testing. Springfield, IL: Association of Official Seed
Analysts. 62 p.
Johansen, James H. 1993. [Personal communication].
Provo, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Shrub Sciences
Laboratory.
Meyer, Susan E.; Kitchen, Stanley; Wilson, G. Richard;
Stevens, Richard. 1987. Supporting evidence for the proposed rule: Artemisia tridentata big sagebrush. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station,
Provo, UT. 10 p.
Shaw, Nancy L.; Monsen, Stephen B. 1990. Use of sagebrush for improvement of wildlife habitat. In: Fisser,
Herbert G., ed. Wyoming shrublands aspen, sagebrush and wildlife management: Proceedings 17th Wyoming shrub ecology workshop; 1988 June 21-22; Jackson, WY.
Laramie, WY: University of Wyoming, Department of
Range Management: 19-35.
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12(6): 341-346.
Swift, Dean. 1993. [Personal communication]. Provo, UT:
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Welch, Bruce L.; McArthur, E. Durant, Nelson, David L.;
Pederson, Jordan C.; Davis, James N. 1986. ‘Hobble
Creek’—a superior selection of low-elevation mountain big sagebrush. Res. Pap. INT-370. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain
Research Station. 10 p.
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Sands, Alan R.; Wagstaff, Fred J.; Nelson, David L.
1992. ‘Gordon Creek’—a superior, tested germplasm of Wyoming big sagebrush. Res. Pap. INT-461. Ogden,
UT: U.S. Department of Agriculture, Forest Service,
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