Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2009
Publication Date: 1/16/2010
Citation: Burner, D.M., West, C.P. 2010. Improving tall fescue shade tolerance: Identifying candidate genotypes. Agroforestry Systems. 79(1):39-45. Interpretive Summary: Use of shade tolerant forage species is often a key component of agroforestry practices, especially alley cropping and silvopasture. Tall fescue forage is an excellent forage grass grown on millions of hectares of pasture in the US, but its shade tolerance is rather limited. Fortunately, available populations of tall fescue are genetically diverse. A collaborative study was conducted by scientists at ARS-Booneville, AR and University of Arkansas-Fayetteville to identify plants that might yield well under artificial, 60% shade. After three years of testing, 11 plants were identified which had above average yield under shade. Future research is needed because growth in tree shade also requires that plants can compete well with trees for soil water. Vigorous, shade tolerant germplasm developed from this study could improve forage productivity in agroforestry practices.
Technical Abstract: Tall fescue (Schedonorus arundinaceus) is genetically variable for many agronomic traits, so it might be possible to increase its persistence and productivity in shaded agroforestry applications. The objective of this research was to identify high yielding, shade-tolerant genotypes. Seed was obtained from eight families: seven plant introductions of European origin: 234718, 234720, 234882, 234884, 235018, 235019, 235036, and one cultivar (Kentucky 31). Two sequential experiments were conducted to select genotypes for dry mass yield during April to September. Experiment (Exp) 1 included 30 genotypes of each of the eight families randomly separated into two microenvironments: artificially shaded with fabric and unshaded. Maximum and minimum yields were 93.9 and 47.1 g family-1 for Kentucky 31 and 235036, respectively. After 1 yr, the proportion of vigorous survivors in Exp 1 was greater in the unshaded than shaded environment (0.40 and 0.09, respectively), and ranged from 0 to 0.56 (235036 and Kentucky 31, respectively). Forty robust genotypes (one later died) from four families (234718, 234720, 235019, and Kentucky 31) were selected from shaded and unshaded microenvironments of Exp 1, clonally propagated, and evaluated in pots for 2 yr in Exp 2. Shade-selected Kentucky 31 yielded more (31.0 g plant-1) in shade than other shade-selected families (25.2 to 25.8 g plant-1). Eleven genotypes in the top quartile (yield > 33.0 g plant-1) were selected for further testing. All genotypes were endophyte (Neotyphodium coenophialum)-infected. Future research will include seed increases and measuring yield in shaded, water-deficit conditions of a tree understory.