Heritability Estimates of Creeping Bentgrass Root Systems Grown in Flexible Tubes

Turfgrass root systems are often concentrated in upper portions of soil profiles, and consequently depend on frequent precipitation or irrigation to avoid drought stress. Development of cultivars with extensive root systems could make use of greater volumes of soil water. We devised a greenhouse screening technique to characterize root systems of creeping bentgrass (Agrostis palustris Huds.), and to estimate the heritability of root characters. Thirteen clones, excavated in the field, exhibited genetic variation in root extension, tiller number, and root number at 10-cm soil depths. Flexible, sandfilled polyethylene tubes were used to screen the same 13 clones in the greenhouse. Rank correlations were significant between field and greenhouse performance in root extension, root number through the 20-cm depth, and tiller number. Parent-progeny regression of 10 creeping bentgrass clones in flexible tubes indicated narrow-sense heritabilities of 0.08,0.14,0.31, and 0.61 for root number at the 10-, 20-, 30-, and 40-cm depths, respectively. Parent-progeny regression indicated narrow-sense heritabilities of 0.07, 0.23, 0.27, 0.43, and 0.82 at soil depths of 5 to 10,11 to 20, 21 to 30, 31 to 40, and 41 to 50 cm, respectively, for root surface areas. Narrow-sense heritability estimates for tiller number and tiller dry weights were 0.31 to 0.41, and 0.32, respectively. Root extension narrow-sense heritability was 0.62 to 0.76, and was not significantly correlated with either tiller number or weight. The heritability estimates for root and shoot characters from these creeping bentgrass clones suggest progress could be made toward development of more drought-avoidant turfgrasses, but selection for high tiller number or weight only will not necessarily yield the desired results. Contribution by the Texas Agric. Exp. Stn. Technical Article no. 25187, Texas A&M Univ. Research supported in part by the U.S. Golf Assoc. and Bentgrass Research, Inc.