Turfgrass Root Systems Evaluated Using the Minirhizotron and Video Recording Methods

Abstract

Nondestructive evaluations of turfgrass root systems have been limited to large rhizotrons. Recent developments in the minirhizotron and associated microvideo camera technologies provide opportunities for quantifying in situ root systems of turfgrass field plots. Minirhizotron root counts were compared with destructive core sampling for root length and weight densities of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) grown under putting green and fairway conditions, and annual bluegrass [Poa annua L. var. reptans (Hausskn.) Timm] grown under fairway conditions. Correlations between minirhizotron root counts and root length density (cm root/cm3 soil), minirhizotron root counts and root weight density (mg root/cm3 soil), and root weight density and root length density (r2 = 0.861, 0.843, and 0.955, respectively) were very highly significant when data were combined across all depth zones for an October sampling of the bentgrass green. Total root numbers observed along minirhizotrons were greatest early in the growing season, followed by a decline during July. Annual bluegrass root measurements were lower than either of the creeping bentgrass turfs. The root system of the creeping bentgrass turfs recovered during late summer, whereas the annual bluegrass turf showed little recovery from summer root decline. Data indicated that minirhizotron estimates provided an acceptable means for characterizing the profile distribution of turfgrass root systems from the soil surface to 300 mm, and possibly deeper into the soil profile.