Summer Root Decline

Abstract

A better understanding of the seasonal dynamics of root activity for creeping bentgrass [Agrostis palustris Huds. = A stolonifera var. palustris (Huds.) Farw.] would be beneficial for developing effective breeding and management programs to maximum summer turf quality. The objectives of this study were to examine dynamics changes in root production and mortality for four creeping bentgrass cultivars that differ in summer shoot performance. The study was conducted on a USGA-specification putting green in Manhattan, KS, during 1997 and 1998. The cultivars evaluated were ‘L-93’, ‘Penncross’, ‘Providence’, and ‘Crenshaw’. Grasses were mowed daily at 4 mm and irrigated on alternate days. Root production and mortality were monitored using the minirhizotron technique. In both years, total root length and number were highest in August and then decreased in September for all four cultivars. From July to September, the length and number of newly produced roots decreased while those of dead roots increased. The ratio of dead roots to live roots in length and number increased in late summer for all cultivars. While the differences in total root length and number among cultivars were not consistent between 2 yr, Penncross consistently had more dead roots, fewer new roots, and higher root mortality compared with the other cultivars. The results indicate that summer root decline of creeping bentgrass resulted from both decreased new root production and increased root mortality, which could be associated with high soil temperatures during the summer. Variation in root production and mortality may contribute to the differences in shoot summer performance of the four cultivars.