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Title: PHYLLOCHRON DEVELOPMENT IN COOL-SEASON FORAGE GRASSES.

Author
item Frank, Albert
item Berdahl, John
item Karn, James

Submitted to: International Grasslands Congress
Publication Type: Proceedings
Publication Acceptance Date: 5/24/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Plant growth staging is a useful approach to determining grazing readiness of forage grasses, but more information is needed on leaf insertion rates and on whole plant development among species and improved cultivars. A study was conducted to evaluate fall leaf initiation, spring leaf initiation or phyllochron, and growth stage at stem apex differentiation of fcrested wheatgrass, intermediate wheatgrass, western wheatgrass, smooth bromegrass, and green needlegrass. Results showed that a good relationship exists between plant leaf insertion and growing degree-days which can be used for predicting growth stages and grazing readiness. Species developed leaves at different rates, thus a separate equation is needed to predict species growth stages. These results increase our understanding of forage grass development which has utility in making management decisions on time to start grazing. Grazing at the proper time improves rangeland and seeded dgrassland sustainability and conservation of the grassland resources.

Technical Abstract: The purpose of this study was to evaluate the relationship between grass leaf insertion rate and accumulated growing degree-days, and determine the phyllochron for five perennial forage grass species and two cultivars of each species. Species field seeded in solid stands were crested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult.], intermediate wheatgrass, [Thinopyrum intermedium Barkw. & Dewey:Syn:A. intermedium (Host) Brauv], western wheatgrass [Pascopyrum smithii (Rybd) Love], green needlegrass (Stipa viridula Trin.), and smooth bromegrass (Bromus inermis Leyss). Species phyllochron differences ranged from 77 GDD for Mandan 404 smooth bromegrass to 114 GDD for Lodorm green needlegrass. Phyllochron differences were greater among species than cultivars within species which suggests a single equation is adequate for predicting species phyllochron for determining grazing readiness.