Browsing Journal of Range Management, Volume 37, Number 3 (May 1984) by Title
Now showing items 25-27 of 27
Temperature Profiles for Germination of Two Species of WinterfatGermination of seeds of winterfat [Ceratoides lanata (Pursh) Howell] and Eurasian winterfat [C. latens (J.F. Gnel.) Reveal and Holmgren] was compared at 55 constant and alternating temperatures. The seeds of both species germinated at a wide range of temperatures. Optimum germination (defined as not lower than the maximum and its 0.01 probability confidence interval) occurred most frequently at 0, 2, and 5 degrees C cold period temperatures alternating with 15 and 20 degrees C. Optimum temperature regimes tended to be slightly warmer for seeds of Eurasian winterfat. There were large year-to-year differences in the quality of Eurasian winterfat seeds. Three sources of winterfat purchased from commercial seed dealers had low to very low germinability. Seeds of the Hatch selection of winterfat that we tested had a germination response equal to or better than the commercial sources of winterfat seeds.
Threshing Damage to Radicle Apex Affects Geotropic Response of WinterfatThe acute end of a winterfat [Eurotia lanata (Pursh) Moq.; Ceratoides 1. (Pursh) J.T. Howell] seed is formed by the apex of the radicle and of the cotyledons. It is postulated that this shape makes the embryo root cap especially susceptible to damage during threshing and that such damage is the cause of a high percentage of threshed germinated seed (germinant) lacking positive geotropism. This study consisted of examining germination behavior and post germination anatomy of the root apex of germinants with and without positive geotropism. The radicle apex was found to be damaged in 25% of the threshed seed. Eighty-five percent of the germinants from undamaged seed had positive geotropism as compared to 53% from the damaged seed. The latter had a range of anatomical aberrations in which the root cap was missing or seriously abnormal. It is concluded that the standard method of hammer mill threshing of winterfat fruits results in 25% of the seed sustaining damage to the radicle apex. This damage causes a loss of root cap functions, particularly the sensing of gravity. It is recommended that plantings be made by broadcasting whole fruits, rather than by drilling threshed seed.
Vegetation Change after 13 Years of Live-Stock Grazing Exclusion on Sagebrush Semidesert in West Central UtahRange managers often assume that release of vegetation from livestock grazing pressure will automatically result in a trend toward the pristine condition. The pathways and time scales for recovery are also sometimes assumed to be the same as for retrogression. These assumptions were examined via monitoring of plant community composition and forage production in five large paddocks of sagebrush semi-desert vegetation in west central Utah over a 13-year interval. No significant increases in native perennial grasses were noted over this period despite a trend toward more favorable precipitation in recent years. Thus, the present brush-dominated plant community is probably successionally stable. A return to vegetation similar to the original sagebrush-native grass mixture is unlikely. The possibility of a successional deflection via fire is enhanced by the increase of annual grass. Improvement of forage production in this vegetation will not necessarily follow after livestock exclusion. Direction manipulations are mandatory if rapid returns to perennial grass dominants are desired in such environments.