353 Evaluation of Native and Invasive Seed Germination Ability After in Situ Incubation in the Rumen for Rangeland Restoration Through Targeted Seed Supplementation

Abstract

Abstract Changes to native plant compositions of drylands are often associated to loss of wildlife, increased frequency, and severity of wildfires; further, it complicates the grazing permits and allocation during periods of restoration. The goals herein investigate the germination rates of native seed species after in situ incubation to evaluate their potential dispersal as supplements for grazing cattle. Native: Indian ricegrass (Achnatherum hymenoides; ACHY), white yarrow (Achillea millefolium; ACMI), crested wheatgrass (Agropyron cristatum; AGCR), sagebrush (Artemisia tridentata; ARTR), fourwing saltbrush (Atriplex canascens; ATCA), bottlebrush squirreltail (Elymus elimoides; ELEL), bluebunch wheatgrass (Pseudoregneria spicata; PSSP), and gooseberryleaf globemallow (Sphaeralcea grossulariifolia; SPRT) and nonnative: cheatgrass (Bromus tecorum, BRTE; fall BRTEf and spring seeds BRTEs) seeds were examined. Four ruminally canulated Angus x Hereford steers adapted to a forage kochia-alfalfa diet were utilized for seed incubations. Seeds were weighed into 84 bags at a rate of 5 g per bag (duplicated within and in different animals). Seeds were incubated sequentially (0, 6, 12, 24, 36, 48, and 96 h) and removed at the 96-h point when seeds were thoroughly washed and immediately counted (50) on square 80 mm 80 mm commercial sterile petri dishes with moisture pads and 5 mL of water. Seeds were incubated at 20 °C with 12 h of light/no-light intervals. Germination plates were incubated for 50 d and counted every 10 d for germinations. Generalized linear models assuming a Poisson distribution with separation of means through Dunnett’s multiple comparisons test. Statistical significance was declared at P < 0.05. All statistical analyses were performed on R (R Core Team 2022). Incubation times inside of the rumen linearly decreased germination rates across most seed species. For BRTEs, germination completely stopped at 48 h with a steep decrease observed after 24 h incubation. The BRTEf were also incubated but showed low germination both before and after rumen exposure (winter dormancy). Though ARTR is very important in rangeland restoration in the intermountain west, its germination declined more than 85% within just a 6 h incubation in situ (P < 0.001). A significant germination decrease was observed for AGCR at 36 h; however, germination was full at 48 h and 50% of the original at 96 h (P < 0.05). For ACMI, germination rates significantly declined after 36 h incubation, and for PSSP after 24 h. Low germinations were observed for ACHY, SPRT, and ATCA even with high reported in-bag tetrazolium chloride viabilities. Our results highlight that cattle grazing of cheatgrass does not spread seeds through fecal pats. Additional tests are required to determine seed viability of the dormant (low germination) BRTEf. Seed toleration to ruminal degradation highlights the potential targeted seed supplementation during grazing for rangeland restoration.