Comparison of growth and physiological characteristics between roughstalk bluegrass and tall fescue in response to simulated waterlogging

Abstract

Roughstalk bluegrass (Poa trivialis) is a weed in cool season grass seed production fields in Oregon. Populations of this weed are often greater in fields prone to waterlogging. A greenhouse study was conducted to investigate the morphological and physiological differences between recently established roughstalk bluegrass and tall fescue (Lolium arundinaceum) plants in response to simulated waterlogging. Differences in root morphological development and root respiration were found between waterlogged tall fescue and roughstalk bluegrass. Plants after 4 weeks of waterlogging, leaf number, plant height, and root biomass were reduced more in tall fescue than in roughstalk bluegrass plants. The root length increased 6% in waterlogged tall fescue plants, and decreased 42% in waterlogged roughstalk bluegrass plants, which lead to a shallower root system in roughstalk bluegrass. Root aerenchyma area increased more in waterlogged roughstalk bluegrass than in tall fescue. Alcohol dehydrogenase and lactate dehydrogenase activities increased in the roots of both species, but not in the leaves. The increases were greater in tall fescue than in roughstalk bluegrass. Turf quality, aboveground biomass, photosynthetic capacity, and water-soluble carbohydrate concentrations were reduced by waterlogging, but there were no differences over time or species. Thus, the shallower root system, larger aerenchyma, and reduced fermentation rates were the characteristics most likely to contribute to better waterlogging tolerance in roughstalk bluegrass compared to tall fescue and invasion of roughstalk bluegrass in waterlogged cool season grass seed fields.

Morphological and Physiological Responses of Seashore Paspalum and Bermudagrass to Waterlogging Stress

“…However, the development of aerenchyma was significantly greater in waterlogged seashore paspalum than bermudagrass with greater porosity seen in waterlogged seashore paspalum than in bermudagrass. Our study is consistent with the results of Liu et al (2017), who reported that the increase of aerenchyma in waterlogged roughstalk bluegrass was greater than in waterlogged tall fescue and was one of the characteristics most likely to contribute to better waterlogging tolerance in roughstalk bluegrass. Increased aerenchyma formation was also observed in flooding-tolerant Paspalum dilatatum (Insausti et al, 2001), and waterlogged Dendranthema species (Yin et al, 2010).…”

“…Our results indicated that root metabolism was more sensitive to waterlogging than leaf metabolism. Similar results were reported by Liu et al (2017). Plant tolerance to waterlogginginduced hypoxia appeared to be associated with low root respiration in wheat [Triticum aestivum (Huang and Johnson, 1995)].…”

“…The maintenance of photosyn-thesis in seashore paspalum provides further evidence of improved waterlogging tolerance compared with bermudagrass. Reduced photosynthesis has been reported in many dryland species under waterlogging (Ahmed et al, 2002;Liu et al, 2017;Naidoo and Mundree, 1993). Rapid declines in g S were observed in several plant species under flooded conditions (Else et al, 1995), and stomata closure is considered to be a major reason for reduced photosynthesis during flooding (Pezeshki et al, 1996).…”

“…Root diameter is also associated with waterlogging tolerance. Liu et al, (2017) reported that the root diameter of roughstalk bluegrass was less than tall fescue, and roughstalk bluegrass had more total roots than tall fescue. Root systems with smaller diameters have greater surface-area to volume ratios (Lamont, 1983).…”

“…Aboveground changes caused by waterlogging vary with grass species and genotype. Liu et al (2017) reported that after 4 weeks of waterlogging, leaf number and plant height were reduced both in tall fescue and roughstalk bluegrass [Poa trivialis (Liu et al, 2017)]. However, Zhang et al (2013) reported that the waterlogging treatment significantly increased shoot dry weight in tall fescue and kentucky bluegrass (Poa pratensis).…”