Abstract
Revegetation of degraded shrub-steppe often fails due to intense competition from weeds, highly variable environmental conditions, and limited soil moisture. The objective of this study was to test whether a commercially available seed coating and a water-retaining acrylamide copolymer hydrogel would increase seedling emergence and establishment of crested wheatgrass (Agropyron cristatum) under three watering frequencies and two soil textures. Pots were filled with one of four soil treatments: field soil, two parts field soil mixed with one part sand, field soil plus hydrogel, or field soil plus sand plus hydrogel. We seeded the pots with coated or uncoated seed and placed them in a greenhouse for 66 days. The pots were assigned one of three watering treatments: 4.5 oz (150 ml) applied one time per week, 1.5 oz (50 ml) applied three times per week, or 0.9 oz (30 ml) applied five times per week. We recorded seedling emergence at three and six weeks. At the end of 66 days, the numbers of seedlings that survived were counted and aboveground biomass was collected, dried, and weighed. We found that uncoated seed had 1.6 times greater seedling density than coated seed. Incorporation of the acrylamide copolymer hydrogel into the potting medium conferred some benefit to emergence, biomass, and survivorship of crested wheatgrass seedlings. However, it was watering frequency that produced the most consistent influence on seedling emergence, survival, and biomass. Watering three or five times per week increased emergence more than watering one time per week, but watering one time per week generally led to greater survivorship and biomass. This suggests that the use of water-retaining hydrogels may help to overcome soil moisture limitations and improve seedling establishment during revegetation of degraded shrub-steppe.
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