SEED WEIGHT AND GERMINATION TIME AFFECT GROWTH OF 2 SHRUBS

The objective of this study was to investigate relationships between s eed size, time of germination, and seedling growth in winterfat (Cerat oides lanata (Pursh) J. T. Howell) and silver sagebrush (Artemisia can a Pursh), Individual seeds of winterfat were placed into 6 weight clas ses ranging from 1.5-2.0 to > 4.0 mg seed(-1) while silver sagebrush s eeds were separated into 7 classes ranging from 0.53 to 0.83 mg seed(- 1). Seeds were incubated at 18 degrees C, seedlings with radicles < 3. 0 mm were removed at 1, 2, 3, 4-5 and 6-12 day intervals, grown 5 days in darkness at 18 degrees C, and axial length measured. Total germina tion of winterfat increased 5.5% mg(-1) increase in seed weight, but g ermination rate was similar among weight classes, averaging 53.1% day( -1). Seed weight and time of germination interactively influenced grow th of winterfat seedlings, Seedling length of winterfat was more than 2-fold greater in the > 4.0 than the 1.5-2.0 mg seed(-1) class while l engths of seedlings in the > 2.0-2.5 through > 3.5 to 4.0 mg seed(-1) weight classes were intermediate. Seedling length decreased 0.9 to 3.3 mm for each day that germination was delayed from 1 to 12 days with t he least and greatest reductions occurring for lightest and medium wei ght seeds, respectively. Total germination for silver sagebrush initia lly increased with seed weight, but declined at weights greater than a bout 0.57 mg seed(-1); germination rate was similar (57.1% day(-1)) am ong weight classes. Seedling length of silver sagebrush increased 0.3 mm mg-l increase in seed weight whereas length decreased curvilinearly as time to germination was delayed. When winterfat is used for restor ation, relatively heavy seeds should be used because they have the gre atest germination and produce large seedlings, Because seedling length of silver sagebrush increased with increasing seed weight it is also desirable to select heavier seeds; however, reduced germination in hea vier seeds may necessitate increasing seeding rates.