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This article in CS

  1. Vol. 32 No. 6, p. 1371-1376
     
    Received: Dec 27, 1991


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doi:10.2135/cropsci1992.0011183X003200060013x

Growth Analysis of a Tall Fescue Sward Fertilized with Different Rates of Nitrogen

  1. Gilles Bélanger ,
  2. François Gastal and
  3. Gilles Lemaire
  1. Agriculture Canada, Research Station, P.O. Box 20280, Fredericton, NB E3B 4Z7, Canada
    Station d'Ecophysiologie des Plantes Fourragèeres INRA, Centre de Recherches de Lusignan, 86600 Lusignan, France

Abstract

Abstract

Nitrogen fertilization increases yield of perennial grasses, but little knowledge exists on the effect of N fertilization on growth processes at the sward level. Growth of an irrigated tall fescue (Festuca arundinacea Schreber) sward fertilized with different rates of N was analyzed during two summer regrowths (1987 and 1988) and two spring regrowths (1987 and 1989). When no N was applied, cumulative shoot growth at the end of each regrowth period (summer 1987, summer 1988, spring 1987, and spring 1989) was 29, 15, 36, and 42% of that obtained with the highest N rate used in that period (160, 240, 200, and 180 kg N ha−1), respectively. Analysis of the N nutrition status of the sward based on the concept of an optimal N content indicated that N was not limiting shoot growth at the highest N rates used in any of the regrowths except during the summer of 1987. Radiation-use efficiency at the highest N rate was 1.68 and 1.82 g DM MJ−1 in the summer regrowths of 1987 and 1988, and 1.83 and 2.16 g DM MJ−1 in the spring regrowths of 1987 and 1989. Cumulative intercepted photosynthetically active radiation (PAR) and radiation-use efficiency both increased with an increase in N rates. The effect of the N deficiency on cumulative intercepted PAR was, for the most part, limited to situations where the relative N concentration was <0.5. Radiation-use efficiency, however, was affected through most of the range of relative N concentrations.

Contribution of the Station d'Ecophysiologie des Plantes Fouragères INRA.

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