PS 30-194 - Effect of sediment composition, planting depth, and stem length on establishment of ecotypes of giant bulrush [Schoenoplectus (formerly Scirpus) californicus]

Tuesday, August 8, 2017
Exhibit Hall, Oregon Convention Center
Ian J Markovich, Lyn A Gettys and Kyle Thayer, Agronomy, University of Florida, Davie, FL

Diverse ecosystems play a crucial role for Florida’s citizens, visitors, and fauna. Many of our natural resources are being degraded as a result of development, agricultural activities and various other pressures. Healthy aquatic systems should contain diverse collections of native plants, which include submersed and emergent species. A primary goal of many resource managers is to enhance and improve habitats in natural areas by designing restoration projects that focus on planting native species. Although many bulrush plants are installed by FWC personnel every year, they have poor establishment and high mortality rates. The objective for this experiment was to evaluate one nursery-grow and five wild-collected geographically discrete ecotypes of giant bulrush under common nursery conditions to determine how selected environmental factors affect growth and productivity. Each ecotype was tested in a 5x4x3x2 factorial design (five substrate types, four fertilizer rates, three planting depths and two pre-plant stem lengths), with four replicates of each treatment combination. All plants were grown in “azalea” pots for 16 weeks; height and stem counts were recorded and plants were then subjected to a destructive harvest.


Initial analysis of variance revealed that substrate composition had no effect on bulrush growth. The most important main effects were pre-plant treatment (cut vs. uncut/intact stems) and ecotype, followed by fertilizer rate and water depth. Plants with uncut/intact stems were more productive than plants with stems cut to 30cm above substrate level. The Lake George ecotype produced the greatest number of stems, greatest stem height and heaviest roots, whereas the nursery-grown ecotype had the greatest stem dry weight, but there was no difference in total dry weight of these two ecotypes. Plants grown without fertilizer were consistently smaller, lighter-weight and had fewer stems than plants grown with 1, 2, or 4 g/L of fertilizer, but there was no difference among plants grown with any amount of fertilizer. Plants grown with 20cm of water above the substrate produced stems that were heavier, taller, and more plentiful than plants grown in deeper or shallower water. These experiments revealed that pre-plant treatment (cut vs. uncut/intact stems), ecotype, fertilizer rate and water depths affect bulrush growth and can be useful to resource managers hoping to improve bulrush establishment in restoration projects.