Miscanthus×giganteusgrowth and control in simulated upland and wetland habitats

Abstract

Globally, M. x giganteus is used as a biofuel crop due to its ability to persist in a wide range of climates. However, little work has assessed M. x giganteus ability to invade and persist in wetland habitats. In outdoor mesocosms, we examined M. x giganteus ability to grow in simulated wetland vs. upland habitats and examined chemical control strategies for both habitats using aquatic labeled herbicides. M. x giganteus growth was consistently greater in simulated wetland habitats with wetland plants 2.4 to 3 times taller than upland plants six weeks after treatment (WAT) and 2.8 to 3.3 times taller than upland plants 12 WAT. M. x giganteus aboveground (AG) biomass was 12.7 to 17.7 times greater in wetland versus upland grown plants six WAT and 9.6 to 12.5 times greater 12 WAT. Belowground (BG) biomass was 4.5 to 10.7 times greater in wetland versus upland grown plants six WAT and 4.0 to 6.1 times greater 12 WAT. M. x giganteus BG biomass was always greater than AG in both habitats six (6.0 times greater in wetlands and 2.9 times greater in uplands) and 12 WAT (3.8 times greater in wetlands and 1.3 times greater in uplands). Generally, all herbicide treatments reduced M. x giganteus height (66 to 100% reduction) and biomass (84 to 100%) compared to non-treated plants 12 WAT, however, glyphosate (5,716.3 g a.i. ha-1) and imazapyr (1,120.8 g a.i. ha-1) performed better than imazamox (560.4 g a.i. ha-1) and penoxsulam (98.6 g a.i. ha-1). This is the first work to provide evidence that M. x giganteus can be chemically controlled in wetland habitats. Furthermore, this is the first work to show that penoxsulam (an ALS inhibiting herbicide) can reduce M. x giganteus growth in upland or wetland habitats.