PELLET SEEDING OX WESTERN RAXGELANDS ." 



Effects of pelleting, 



Seed damage as the result of heavy compression during processing 

 is probably both mechanical and physiological. Tisdale and Piatt 

 (1951) found an average of 38 percent of broken seeds in crest ed 

 wheatgrass pellets from five projects in Utah, Idaho, Nevada, and 

 Wyoming. Stevenson (1949) reported many broken seeds in crested 

 wheatgrass pellets made at Thorn Creek, Idaho. Bleak and Phillips 

 (1950) observed that pelleting damaged and broke about 25 percent of 

 the seeds of smooth brome and tall oatgrass on the Manti-LaSal 

 project. 



Viability of apparently unbroken seed of most species is reduced 

 in pelleting by compression. Only small, hard, rounded seeds of a 

 few species maintain a reasonable percentage of viability. Germina- 

 tion percentages of pelleted and nonpelleted seed on the Manti-LaSal 

 project are shown in table 1. Data from several sources on percentage 

 of germination of pelleted and nonpelleted seed are as follows: 



Location Authority 



Idaho Tisdale & Piatt (1951) 



Utah Do. 



Arizona. __ Allen (1948). 



Idaho Stevenson (1949). 



__do Tisdale & Piatt (1951). 



Allen (1948) found that 38 percent of the pellets containing crested 

 wheatgrass seed from the early Arizona seedings failed to produce any 

 seedlings. Similar results were obtained at the Federal-State Seed 

 Laboratory in Sacramento, Calif. 3 



The slower rate of germination or death of sound seeds following 

 pelleting by compression is presumed to result from secondary effe - 

 of pressure or a curtailed oxygen supply (Silen, 1948; Bleak and 

 Phillips, 1950; Tisdale and Piatt. 1951). Moomaw et al. (1954 

 determined by the vital-stain technique that the nongerminating, but 

 sound-appearing, seeds were dead rather than merely dormant. 



Pellet behavior 



One advantage of compressed earthen pellets is that they weigh 

 enough for good aerial distribution, even in moderate winds. The 

 claim that these pellets had enough weight to cause them to penetrate 

 range soils (Ashley, 1945 • was not realized. On pellet seedings in 

 Idaho there was seldom any penetration of soft or even wot soil, let 

 alone normal range soils (Tisdale and Piatt. 1951). In Arizona, ei 

 on moist areas around ponds and lakes, the pellets usually hit. L< 





Germination 





Pelleted 



Nonpelleted 



Species 



(percent) 



(percent) 



Crested wheatgrass 



9 



68 



Do 



12 



84 



Do 



10 



86 



Do 



25 



73 



Yellow sweet clover 



38 



78 





3 Unpublished data from the U.S. Bureau of Indian Affairs. 

 669605 0—63 2 



