Cultivar and Cultivar ✕ Environment Effects on Relative Feed Value of Temperate Perennial Grasses
Cultivar evaluation trials for perennial forage grasses traditionally have emphasized forage yield and adaptation characteristics, such as maturity, pest resistances, and stress resistances. The objectives of this study were to evaluate cultivar effects and cultivar ✕ environmental factor interactions for relative feed value (RFV) of several grass cultivars grown in binary mixtures with alfalfa (Medicago sativa L.). Grass species were ryegrass (Lolium spp., including perennial [L. perenne L.], intermediate [L. hybridum], and festulolium [Festulolium braunii K.A.]), orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.), timothy .(Phleum pratense L.), and tall fescue (Festuca arundlnacea Schreb.). Relative feed value was computed, as an index of forage nutritive value, from neutral and acid detergent fiber (NDF and ADF). Cluster analysis revealed that environments based on similar cuttings and from the same year tended to cluster together. Only cultivars of orchardgrass, ryegrass, and timothy varied in RFV. Cultivar ✕ environment interactions were species-specific. In orchardgrass and timothy, much of the variation was due to differences in cultivar maturity at first cutting. These maturity effects also carried over into second-cutting RFV for timothy. For perennial ryegrass, tetraploids ranked higher in Cut-I RFV than diploids, but did not differ in Cut-2 RFV. Cultivars in at least three perennial forage grass species can be separated according to their RFV by replicated testing in multiple environments. Replication over at least eight environments is necessary to develop broad cultivar inferences. It was possible to discern consistent tendencies across environments only in orchardgrass and timothy, the species for which RFV was related closely to maturity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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