PSVI-27 - Evaluation of coated and non-coated seed species pertinent to the Great basin in response to in vitro ruminal incubation

Abstract: Target grazing has exhibited itself as an effective method of invasive weed mitigation across degraded rangelands in the Great Basin. Additionally, if the seeds of target species are supplemented into the diets of ruminants, they can serve as vectors for the dispersal of native seed species through fecal pats, which may prove to be a useful tactic for rangeland rehabilitation. However, a challenge associated with seed supplementation, is that the seeds of many target species are sufficiently degraded in the rumen. Therefore, the aim of this study was to evaluate the effects of seed coating technologies on germination rates post ruminal in vitro incubation. In vitro incubations were performed on seven species of seeds pertinent to the Great Basin: Achnatherum hymenoides (ACHY), Achillea millefolium (ACMI), Agropyron cristatum (AGCR), Atriplex canascens (ATCA), Elymus elymoides (ELEL), Pseudoregneria spicata (PSSP), and Sphaeralcea grossulariifolia (SPRT) uncoated (control) or coated with either Polyvinylpyrrolidone (PVP) or PVP+ ethocel, as well as uncoated Bromus tectorum (BRTE) seeds. A Daisy II incubator (Ankom Technology, Macedon, NY) was used for the in vitro analysis with rumen inoculum from two rumen-cannulated crossbred Angus steers (body weight: 910.5 ± 34.5 kg) and a buffer ratio of 1:4. Two F57 filter bags containing 1 g of seeds per treatment (control, PVP or PVP+ethocel) were then placed inside of the Daisy II incubator and kept at 39°C for 12 and 24 h for the control treatments, and for 12, 24, and 48 h for the PVP and PVP+ethocel coating treatments. For uncoated seeds, ACHY germination by 24h was higher when compared to 0h (P < 0.05), whereas ATCA germination rate decreased linearly by 12h (P < 0.05). No differences were observed over time on germination rates of BRTE, as well as all of the other uncoated seeds (P > 0.05). When seeds were coated with PVP, ATCA germination rates started to linearly decrease by 12h (P < 0.05), whereas, PVP coated ACMI germination rates only started to decrease by 24h (P < 0.05). The germination rates of PVP coated ELEL and PSSP seeds only started to significantly decrease by 48h (P < 0.05). When coated with PVP + ethocel, the observed germination rates were similar to those observed for PVP coated seeds. However, when compared to uncoated seeds, coating with PVP + ethocel seem to decrease germination rates of ACMI and ATCA by 0h (P < 0.05). No changes on germination rates were observed over time for coated and uncoated AGCR and SPRT (P > 0.05). In conclusion, seed germination rates after in vitro incubation were not increased by coating the seeds with PVP or PVP + ethocel.