Allelopathic and Competitive Effects of Tall Fescue on Weeds

다국어 초록 (Multilingual Abstract)

Greenhouse and growth chamber trials were conducted at Virginia Tech's Glade Road Research Facility in Blacksburg, VA, USA to 1) examine the impact of three tall fescue mowing heights on canopy architecture, soil-surface temperature, light penetration, and seedling establishment of six weeds, and 2) determine whether soil leachate or aqueous leaf extract collected from tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] affect seed germination and growth of annual bluegrass (POa annua L.), crabgrass [Digitaria sanguinalis (L.) Scop.], and goosegrass [Eleusine indica (L.) Gaertn.].
Turf-type tall fescue mown at 3.8 cm for one year reduced penetration of photosynthetically active radiation (PAR) at 1 cm above soil level by 43%. For each cm increase in mowing height, PAR decreased an additional 4.4% such that PAR was reduced 90% at the highest mowing of 11.4 cm. Canopy coverage, assessed via digital analysis of images collected from a 0.6-cm tall micro camera, decrease with mowing height in trends that mirrored that of PAR penetration. A concomitant linear decrease in temperature was also related to increased mowing height. Although many weed seedlings were observed at 14 d after seeding, most died by 28 d after seeding. Seedling counts at 28 days after seeding were reduced by tall fescue competition for all species but only annual bluegrass, dandelion (Taraxacum officinale F.H. Wigg.), and white clover (Trifolium repens L.) seedling counts were dependent on mowing height. Percentage reduction in 28-d seedling counts increased linearly with mowing height and were 77 to 88% for annual bluegrass and 43 to 77% for white clover. Dandelion seedling counts were at least 25% reduced at tall fescue mowing heights of 3.8 or 7.6 cm and 100% reduced by tall fescue mown at 11.4 cm. Soil leachate collected from tall fescue turf did not inhibit germination or seedling growth of annual grassy weeds. Extracts of ground tall fescue leaves reduced annual bluegrass germination and seedling vigor more when leaves were collected from plants grown in cool (7.2 C) versus warm (35 C) conditions.