ROOT GROWTH OF EASTERN GAMAGRASS: A FOUR-YEAR STUDY

Authors: Ritchie, Jerry; GITZ, D - CROPPING SYSTEMS RESEARCH

Submitted to: Eastern Native Grass Symposium
Publication Type: Proceedings
Publication Acceptance Date: 8/17/2006
Publication Date: 10/11/2006
Citation: Ritchie, J.C., Gitz, D.C. 2006. Root growth of eastern gamagrass: A four-year study. In: Proceedings of the Fifth Eastern Native Grass Symposium, October 10-13, 2006, Madison, Wisconsin. p. 42-47.

Interpretive Summary: Eastern gamagrass (EGG) is a robust, perennial, warm season, bunchgrass that is native to the U.S. Eastern gamagrass is also fast growing, drought tolerant and grows where fertility is low. The drought tolerance is attributed the deep rooting characteristics of gamagrass. In this study we used a minirhizotron digital video systems and found root growth to be rapid under eastern gamagrass with roots reach 30 to 40 inches in one growing season. Root occupancy reached between 50 and 60% by the end of the first growing season and has persisted at those levels for the four years. A pattern of root loss during the dormant season and new root growth during the following growing season was found under the rows of eastern gamagrass plants. Between the rows eastern gamagrass did not show this pattern of root loss and have slowly increased in root occupancy during the four-year study period. This study suggests an inverted cone or fan distribution of roots under the eastern gamagrass plants. This study also shows the rapid development and persistence of roots under eastern gamagrass.

Technical Abstract: Eastern gamagrass cv. “Pete” [Tripsacum dactyloides (L) L.] was planted in a 100 x 100 ft. field in 30-in. wide rows on May 15, 2002. Twelve minirhizotron access tubes (5 ft. long) were installed parallel to the rows at 45-degree angles and installed in pairs either in (in-row) or midway between the rows (between-row). Root images were collected at 0.4-in. intervals to a depth of approximately 40 in. (100 images for each tube). In situ images were collected at approximately 1-week intervals in 2002 beginning 1-month after planting, 2-week intervals in 2003, and 3-week intervals in 2004 and 2005 during the growing season using the Bartz minirhizotron imaging system. One month after planting total root occupancy (percent of images from a tube with roots) was 1.5 and 0.0% for in-row tubes and between-rows tubes respectively. By the end of the first year, root occupancy was 45% for the in-rows tubes and 15% for the between-row tubes. Several in-row tubes had roots reaching a depth of 3 to 4 ft. At the end of the second year approximately 50 and 40 % of the images for the in-row and between-row tubes, respectively had roots with many reaching 3 to 4 ft depths at the in-row sites. At the end of the third year root occupancy was similar to the second year but the number and size of roots in the images had increased. The fourth year patterns were similar to the third year patterns. This study shows the rapid root develop for eastern gamagrass plants and is suggestive of a fan-like distribution of roots under the developing crowns