Effects of Fertilizers on Medusahead Seedbank Potential and Seedling Growth.

Medusahead, an annual grass, is an invasive plant that has taken over large proportions of rangeland in Utah and nearby states. Medusahead is difficult to control and livestock avoid eating medusahead. It has high silica content, and creates thick patches of thatch that choke out other plants.  Medusahead reduces habitat, grazing potential, and the overall value of an entire ecosystem. Chemical control is highly variable and not an economically viable solution. Ranchers need an affordable solution to control this weed. Six fertilizer treatments were examined in this study:  1) Nitrogen - Early; 2) Nitrogen - Late; 3) Nitrogen + Phosphorus; 4) Nitrogen + Phosphorus + Sucrose; 5) Sucrose; and 6) Control.  The following year, soil and litter samples were collected from each plot to a depth of 2.5 cm, spread in germination boxes and watered with an aqueous solution of  0.1 mmol of potassium nitrate and 0.72 mmol gibberellin to break any seed dormancy.  The seeds were allowed to germinate for four weeks and seedling counts determined. To determine the effects of the fertilizer treatments on seedling growth, medusahead plants were randomly collected from each plot.  Seeds were planted individually in germination tubes filled with sand, watered with plain water and incubated at 13˚ C for four weeks.  Germination boxes were checked daily and the date of germination was noted.   Each seedling, ten days after germination, was pulled and further evaluated for total, root, and shoot length, and total, root, and shoot wet and dry weights were determined. Preliminary results indicate that late applications of nitrogen result in reduced medusahead seedbank potential.  Fertilizer additions generally increased the lengths and weights exhibited; whereas, sucrose appeared to have no effect.