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Comparison of Cultivars

An effective method is needed to compare these cultivars for both yield and quality. Currently for grass cultivar trials, all entries in a trial are harvested on the same day, regardless of maturity, or an attempt is made to harvest entries at a similar maturity stage. It is difficult to make varietal comparisons using either of these methods. Same-day harvesting of cultivars is biased by plant maturity differences. Harvesting on different days to correct for plant maturity is biased by the differing environmental conditions preceding each harvest date. Normally forage NDF increases steadily in the spring, but it is possible for forage NDF to temporarily drop as much as 5 percentage units following a stretch of cold weather, due to an accumulation of sugars. Harvest on different days cannot take weather shifts into account. Adjusting yield and quality for maturity (e.g. heading date) is not satisfactory, as the relationship between heading date and both yield and quality for a set of cultivars is relatively poor.