PERFORMANCE OF MORPHOLOGICALLY DIVERSE ORCHARDGRASS CLONES IN SPACED AND SWARD PLANTINGS

This study was conducted to determine effects and interactions of plan t density on digestibility and plant morphology of diverse orchardgras s (Dactylis glomerata L.) clones. Propagules of ten orchardgrass clone s with contrasting morphology from two maturity groups (inflorescence emergence differed by 8d) were evaluated in sward (0.15-m centres) and spaced (0.60-m centres) plantings. Plants were harvested from spring growth on a common date near anthesis and from summer growth when abou t 5 weeks of forage growth had accumulated. The plants were separated into morphological parts before measuring their size and in vitro dige stible dry matter (IVDDM). There were few plant density x orchardgrass clone interactions, and correlation coefficients of clones grown at t he two plant densities generally were high (e.g. 0.87 in spring and 0. 67 in summer for IVDDM of total herbage). Plant density had little eff ect on morphology of leaf blades from reproductive tillers, but leaf b lades of vegetative tillers were 12% (spring) and 22% (summer) longer from sward than from spaced plantings. Moreover, reproductive tillers were 26% taller in sward than in spaced plantings. Also, leaf blades o f vegetative tillers in spring growth were more than twice as long, of similar width and 65% thicker than leaf blades from reproductive till ers. Because divergent genotypes respond similarly to plant density, i t is concluded that observations taken in spaced plantings of orchardg rass can be used to make inferences about relative differences in swar d plantings for the traits studied.