Date of this Version
Agronomy Journal July/Aug 1991. v. 83 (4), pp 774-776.
Forage cultivar evaluation is often done in small plots with multiple harvests throughout the growing season. Data is often summarized by presenting a yearly total yield for each cultivar in addition to the mean for each harvest date. Data summarization often becomes burdensome and difficult to interpret. Regressing yield against a growth index associated with harvest dates can be utilized to describe forage performance in a concise and easily interpreted format. Subsets of data from tall fescue (Festuca amndinacea Schreb.) yield trials conducted in Alabama and Kentucky were used to demonstrate the technique. The analysis involves regressing yield of a cultivar against an index calculated as the mean of all entries at a harvest date minus the grand mean. The resulting regression coefficient (b) describes cultivar yield response over several harvests and is indicative of performance under variable growth conditions.