Journal of Range Management, Volume 49, Number 4 (July 1996)

Mon, 01 Jul 1996 00:00:00 GMT

Journal of Range Management, Volume 49, Number 4 (July 1996) Complete digitized issue.

Switchgrass recruitment from broadcast seed vs. seed fed to cattle

Mon, 01 Jul 1996 00:00:00 GMT

Switchgrass recruitment from broadcast seed vs. seed fed to cattle Ocumpaugh, W. R.; Archer, S.; Stuth, J. W. Fecal seeding by livestock may be an effective, low-cost means of rangeland restoration. We compared recruitment of switchgrass (Panicum virgatum L.) from seed fed to cattle and deposited in dung to that of broadcast-seeded plots receiving a comparable number of unfed seed. Although germinability of seed passed through livestock (52 to 62%) was reduced relative to that of broadcast seed (85 to 91%), recruitment of switchgrass from seed in cattle feces was equal to or superior to that of broadcast seed in terms of establishment (frequency of occurrence and density), plant growth and final plant size. The frequency of plot with emerging switchgrass plants ranged from 62 to 100% when seeds were delivered in feces, but only 2 to 40% when seeds were broadcast. After 1 year, the frequency of occurrence of switchgrass plant in fecal vs. broadcast-seeded plot was comparable for autumn trials. However, evaluations 1 year after the spring trials continue to result in higher frequency of plot with switchgrass plant from seed delivered in feces than of broadcast seedings (56 vs. 4% for May 1990, P < 0.05; and 90 vs. 51% for May 1991, P less than or equal to 0.01). Enhanced plant recruitment on fecal-seeded plots occurred even though broadcast-seeded plots received 1.5 to 1.7 times more pure live seed (PLS). Plants on fecal-seeded plots had a greater plant size score (based on visual ratings of height, culm density, and biomass) than plants on broadcast-seeded plots (P < 0.05 for May seedings; P < 0.05 for October 1990; P < 0.10 for October 1991). Results suggest significant advantages of fecal seeding over conventional broadcast seeding in terms of seedling emergence, establishment and growth.

Partial and full dehydration impact on germination of 4 warm-season grasses

Mon, 01 Jul 1996 00:00:00 GMT

Partial and full dehydration impact on germination of 4 warm-season grasses Emmerich, W. E.; Hardegree, S. P. Precipitation patterns in the arid southwest U.S. can be highly variable during the summer monsoon season. The ability of germinating seeds to withstand temporary periods of dehydration may determine their potential for successful regeneration under present and future climatic regimes. Germination with short-term hydration and dehydration sequences was compared to constant water potential germination for sideoats grama [Bouteloua curtipendula (Michaux) Torrey], buffelgrass [Cenchrus ciliaris L.], Lehmann lovegrass [Eragrostis lehmanniana Nees], and kleingrass [Panicum coloratum L.]. Seeds were imbibed at -0. MPa for 1 to 4 days, then either air dried or partially dehydrated d -3.0 MPa for 1 to 4 days before being returned to the initial imbibition solution for a total 14-day incubation-dehydration period. One day of imbibition at -0.2 MPa advanced germination to a stage that resulted in significant reductions (P < 0.05) in total germination from subsequent dehydration. The significant reductions still allowed > 48% of the viable seeds to germinate after dehydration. Longer imbibition times also exhibited significant reductions in germination for buffelgrass and kleingrass. For kleingrass air-dried dehydration compared to -3.0 MPa produced significant reductions (P < 0.05) in germination with 2-3 days imbibition. The length of the dehydration periods produced significant differences (P < 0.05) in total germination for Lehmann lovegrass and kleingrass. Partial dehydration significantly increased germination rate for sideoats grama, buffelgrass, and kleingrass, while air-dried dehydration significantly reduced buffelgrass germination rate. Any dehydration during germination was detrimental and > 1-day imbibition followed by dehydration seemed the critical time upon which a dramatic reduction in germination occurs.

Observations of shoots and roots from interspecific grafted rosaceous shrubs

Mon, 01 Jul 1996 00:00:00 GMT

Observations of shoots and roots from interspecific grafted rosaceous shrubs Kyle, N. E.; Righetti, T. L. Plants with various shoot and root combinations of Cowania mexicana var. stansburiana (Torr.) Jeps. (cliffrose), Purshia glandulosa Curran (desert bitterbrush), and Purchia tridentata (Pursh) DC. (antelope bitterbrush) were relatively easy to produce by grafting. The foreign roots or shoots in multi-shoot or multi-root systems were not as vigorous as the original scion or rootstock. With time the original scion or rootstock became dominant and the foreign portions usually senesced. If growth of the original scion or rootstock was restricted by pruning or removal, satisfactory growth for both shoot or root types occurred. Manipulating grafted systems where Fallugia paradoxa, (D. Don) Endl., Apache plume, (a non-nodulating genus) is combined with any of the above 3 nodulating species was much more difficult. Graft incompatibility occurred in most intergeneric Fallugia systems, but some combinations survived for several years. A large quantity of nodules was produced on 1 very sparsely rooted P. tridentata scion attached to a Fallugia rootstock. Apparently, the plant derived much of its nitrogen from Purshia nodules, and the majority of its other nutrients and water from the Fallugia roots.