Location: Forage and Range Research2013 Annual Report
1a. Objectives (from AD-416):
1. Determine the best seed treatments to maximize germination in basalt milkvetch and western prairie clover. 2. Identify the most appropriate planting depths and seasons that will give the best establishment success for the two legume species. 3. Assess how seed sources will establish across genetic structures and environmental gradients for basalt milkvetch and western prairie clover.
1b. Approach (from AD-416):
l. Determine the best seed treatments to maximize germination: Hard seededness is a common feature in legume species, which limits initial, uniform germination and subsequent establishment. The effects of various seed treatments (mechanical scarification, acid scarification, boiling water treatment, and control) and age of seed (newly harvested up to one-year-old seed) will be investigated for each of the major seed sources of the three legume species. All combinations of these treatments will be tested in a greenhouse to determine which combination of treatments yields the best germination and seedling establishment. 2. Identify planting depths and seasons that will give the best success: Given the data obtained from Objective 1, the best treatment combination will be used in actual field evaluations. Seeds from each species and source will be planted with either a walk-behind drill seeder or a RoughRider range drill. Replicated fall dormant plantings will be compared with spring plantings and tested twice at each of several locations. First and second year establishment/survival will be recorded at each of the test sites. 3. Assess how seed sources will establish across genetic structures and environmental gradients: Up to three locations will be planted for each species. Locations for western prairie clover and basalt milkvetch will be at sites in Oregon, Idaho, and Nevada. Locations for Searls prairie clover will be in northwest and southern Utah and Nevada. Exact test locations will be coordinated with the BLM and USFS, or the USDA-ARS Area-Wide Project, and plots will be protected from grazing. The exact locations will be situated to span genetic structures as well as the environmental gradients shown to be most highly correlated with collection sites. Establishment data will be collected for two years post-planting, but sites will be kept to allow for long-term observation.
3. Progress Report:
The main objectives of this project were to identify techniques that can be used to optimize seed germination and seedling emergence in three legume species native to the Great Basin of the western U.S. including basalt milkvetch, western prairie clover, and Searls’ prairie clover. Project funds are used to defray costs associated with travel to establish and evaluate field plots and hire student workers to assist in field and greenhouse studies. During FY-2013: Seedlots of basalt milkvetch, western prairie clover, and Searls’ prairie clover were subjected to the tetrazolium test to determine seed viability. Although total viable seed in the non-treated seedlots was greater than 85%, viable hard seed ranged from 79-88%. Seedlots were untreated or scarified in a replicated greenhouse study with various soil types, and speed of emergence was determined. Speed of emergence was greatest in western prairie clover, followed by Searls’ prairie clover, purple prairie clover, and basalt milkvetch. All species emerged faster when the seed was scarified; however, this effect was least for basalt milkvetch, which generally had a low rate of emergence. For western prairie clover and Searls’ prairie clover, speed of emergence was greater in the sand compared to the soils with clay. For basalt milkvetch, emergence was slowest in the sandy soils compared to the soils with clay content. Field seeding studies were established at three sites in Oregon. Studies included scarified and non-treated seed of Majestic and Spectrum germplasm western prairie clover and NBR-1 germplasm basalt milkvetch. Preliminary results indicate that spring plantings of the western prairie clover seed were the most successful, and fall plantings of NBR-1 scarified seed were most successful.