Evaluation of native warm-season grass cultivars for riparian zones

Abstract

Aerenchyma are air-filled spaces in the root cortex that help maintain oxygen supply to roots in saturated soils. We examined aerenchyma formation in roots and its effect on the suitability of 26 native warm-season grass cultivars from six species for use in riparian areas. In a greenhouse study, all cultivars exhibited extensive aerenchyma formation in well-drained soil, and percent aerenchyma was greater in the well-drained control than in the saturated treatment (89% versus 71%, respectively). However, the presence of extensive aerenchyma development did not guarantee good root growth under anaerobic conditions. Suitable plant materials for inclusion in riparian areas were found among four of the six warm-season species examined, although a wide range in suitability was observed within species where multiple cultivars were tested. Nine cultivars representing a range of responses were further evaluated at four field locations subjected to flooding and soil saturation. Red River prairie cordgrass (Spartina pectinata L.) provided superior performance at all locations. The worst performing cultivars in the greenhouse study also performed poorly in the field. However, not all cultivars that performed well in the greenhouse also performed well in the field. Osage Indiangrass (Sorghastrum nutans L.) was the third ranked cultivar for flooding tolerance in the greenhouse but had acceptable performance at only one of the four field sites. Conversely, Meadowcrest eastern gamagrass (Tripsacum dactyloides L.) exhibited only moderate flooding tolerance in the pot study but had among the lowest mortality, highest vigor, and highest biomass at three of the four locations. Controlled environment studies were useful for eliminating unacceptable cultivars, but field studies were necessary to identify suitable material for riparian areas.