Christian Christensen, Kevin Kenworthy, John Erickson, Jason Kruse, and Brian Schwartz

Shade decreases both the quantity and quality of light leading to changes in leaf structure and growth rates that reduce turfgrass persistence in reduced light environments.  The overall goal of this study was to identify zoysiagrass genotypes, of Zoysia matrella and Zoysia  japonica, that are able to maintain similar growth habits in shade as would occur in full sun.  The objectives were to quantify the effects of shade on 44 zoysiagrass genotypes’ leaf orientation, relative chlorophyll content, and percent cover.  Forty-four zoysiagrass genotypes were grown in both full sun and 60 percent artificial shade.  Leaf orientation was visually determined using a 1-3 scale (1=most prostrate growth and 3= most vertical growth). Relative chlorophyll content was estimated using a FieldScout CM 1000 chlorophyll meter and rate of spread (percent cover) was visually rated using a grid. Orthogonal contrasts were utilized to determine over several rating dates if genotypes rated similar or different for the above parameters when compared in full sun and shade.  For percent cover the Z. matrella genotypes had slower rates of spread in shade.  Most Z. japonica entries maintained similar rates of spread through the duration of the study.  For leaf orientation, Z. matrella entries, tended to be less effected by shade while overall Z. japonica entries became more upright in the shade. There were not clear patterns between the species for estimated chlorophyll contents, but specific genotypes could easily be identified for having different colors between sun and shade environments.  Based on these parameters the most limiting factor influencing the shade tolerance of Z. matralla is a reduced rate of spread.  In Z. japonica it’s an inability to maintain a horizontal leaf orientation that detracts from shade tolerance.