Characteristics in diverse wear tolerant genotypes of Kentucky bluegrass

Evaluations of Kentucky bluegrass (Poa pratensis L.) wear tolerance have been conducted; however, studies investigating wear mechanisms within this species is limited. This information would be valuable in selecting wear tolerant genotypes. The objective of this study was to identify anatomical and morphological characteristics in diverse wear tolerant Kentucky bluegrasses. Wear treatments were applied to the 2000 National Turfgrass Evaluation Program (NTEP) Kentucky bluegrass field plots in the fall of 2002 at the University of Massachusetts Joseph Troll Turf Research Center at South Deerfield, MA. Wear treatments were applied to 173 genotypes with a differential slip-wear apparatus, and plots were visually rated for wear injury. The 10 most wear tolerant (TOL) and intolerant (INTOL) genotypes were selected for further evaluation. Twelve characteristics were measured in 2003 and 2004 comparing TOL and INTOL genotypes in field plots and as greenhouse grown spaced-plants. Characteristics included tiller density, shoot fresh weight and dry weight, shoot water content, leaf turgidity, number of leaves per shoot, leaf width, leaf strength, leaf angle, and leaf cell wall constituents [total cell wall content (TCW), hemicellulose, and lignocellulose]. Not all differences observed in the greenhouse were present in field plots. Significant differences were found between genotypes and TOL and INTOL groupings. No significant interaction with year was detected. Tolerant genotypes were associated with a more vertical leaf angle, greater TCW and lignocellulose content, and a lower shoot moisture content and leaf turgidity. Leaf angle was the single most important attribute separating wear TOL and INTOL genotypes. Biological explanation for the relationship between leaf orientation and wear tolerance is proposed. These characteristics may be useful as potential selection criteria for breeding to improve wear tolerance within this species.