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Book: Ecology, Production, and Management of Lolium for Forage in the USA
Published by: Crop Science Society of America



  1.  p. 15-28
    CSSA Special Publication 24.
    Ecology, Production, and Management of Lolium for Forage in the USA

    F. M. Rouquette and L. R. Nelson (ed.)

    ISBN: 978-0-89118-603-8


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Physiology and Growth of Ryegrass

  1. S. M. Griffith and
  2. T. G. Chastain
  1. USDA-ARS, Cowallis, Oregon
    Oregon State University, Corvallis, Oregon


The management of economic yields of Lolium sp. in grassland agriculture depends on sound knowledge of plant growth and development. Several features of Lolium physiology and morphology play critical roles in growth, development, and plant productivity. For example, the ryegrass seedling has the greatest rate of growth among cultivated cool-season grasses. This feature gives ryegrass an effective competitive edge in crop or pasture establishment. Further development of the seedling gives rise to leaves and tillers. The tiller, branch or shoot on a ryegrass plant, is the fundamental demographic unit of the ryegrass stand. The fate of tillers is the major determinant of productivity in ryegrass plant populations. The growth environment, as affected by both the natural climatic and edaphic conditions and the influence of management practices, can modify the growth and development of ryegrass. Irradiance and temperature are the most important environmental parameters affecting photosynthesis and hence ryegrass growth and development. Soil N status is the largest single nutrient factor affecting ryegrass growth and development. Effective N management is critical for optimum crop or pasture production. The impact of moisture deficit at critical times in seedling development, crop establishment, or regrowth also can be a major factor limiting crop and pasture production. Among Lolium sp., and genotypes within each species, a continuous gradient of floral induction requirements exist. These range from obligate to facultative requirement for short-days (8 h) or low temperatures (0–3°C) or both, to no environmental stimulus required. In Lolium sp., usually day length-temperature floral induction is associated with perennialness, whereas annualness usually requires only genetic induction. These factors, among others, have important implications with regard to seed production.

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Copyright © 1997. Copyright © 1997 by the Crop Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA