The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Monday, January 28, 2008 - 4:40 PM
Effects of Timing and Intensity of Defoliation on Yield and Seed Production of Sulfur Cinquefoil
Rachel A. Frost and Jeffrey C. Mosley. Department of Animal and Range Sciences, Montana State University, Bozeman, MT 59717
Sulfur cinquefoil (Potentilla recta) is a long-lived perennial weed that is a prolific seed producer and is adapted to nearly every soil type and vegetation complex in the western U.S. This invader reproduces solely by seed and a single plant can produce as many as 6,000 seeds annually. The purpose of this 2-year study was to determine the optimal timing and intensity of defoliation to decrease plant yield and seed production of sulfur cinquefoil plants on foothill rangeland in southwestern Montana . Each year, 150 individual sulfur cinquefoil plants within a 250-m2 enclosure were tagged for identification and assigned to one of 15 treatments with 10 plants per treatment. Treatments were all possible combinations of 3 timings: pre-flower (early June), flower (late June), and seed set (mid-July) at 2 stubble heights, 7.5 cm or 15 cm. Percent cover of sulfur cinquefoil and perennial grasses and the number of stems on each treatment plant were used as covariables in the data analysis (ANCOVA). Response variables collected at seed ripening (early August) included total aboveground biomass, number of buds on each plant, and number and viability of seeds produced. Results from Year 1 indicate that clipping reduced (P ≤ 0.05) yield and bud production of sulfur cinquefoil compared to control plants for all treatments except pre-flower clipped to 15 cm. Clipping to either 7.5 cm or 15 cm at all times or combinations of timings reduced the total number of mature seeds produced per plant by 99% compared to controls. Year 2 results will be discussed. Initial results indicate that defoliation of sulfur cinquefoil can reduce yield and seed production.