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  1. Vol. 29 No. 4, p. 972-976
     
    Received: May 23, 1988
    Published: July, 1989


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doi:10.2135/cropsci1989.0011183X002900040030x

Anatomy of Seed Dispersal Mechanisms in High and Low Seed Shattering Cultivars of Orchardgrass

  1. Marco Piccirilli and
  2. Mario Falcinelli 
  1. C entro Studio Miglioramento Genetico Piante Forraggere del C. N. R., Borgo XX Guigo 74, 06100 Perugia, Italy
    I stituto di Miglioramento Genetico Vegetale dell'Universitá degli Studi di Perugia, Facoltá di Agraria, 06100 Perugia, Italy

Abstract

Abstract

In orchardgrass (Dactylis glomerata L.), seed shattering is a common feature that can be a serious economic problem. To obtain information for breeding improvement programs in seed retention, the mechanism that leads to seed shattering in orchardgrass was histologically determined in two cultivars, Hallmark and Marta, chosen for their different shattering levels. Two abscission layers were identified in both cultivars at the first stage of floral development. A primary abscission layer was located in the rachilla supporting the fertile floret; a secondary layer extended across the pedicel near thebase of the glumes. In Hallmark, seed shattering may occur from the soft dough stage onward because of the disintegration of the cells in the primary layer. In this cultivar the secondary layer remains intact. In Marta, the disintegration of cells in the primary layer gradually occurs over a longer period and seed shattering begins about 30 d after Hallmark and lasts until autumn. In both cultivars the deterioration process observed in the primary layer was probably the consequence of the action of one or more hydrolytic enzymes. During autumn, spikelet dispersion in Martalso occurs because of breakage of the secondary layer. The rupture of this layer was assumed to be mechanical because there was no evidence of cell disintegration.

Research supported by the Natl. Res. Counc. of Italy, Istituto di Miglioramento Genetico Vegetale dell'Universitá degli Studi di Perugia, Borgo XX Giugno 74, 06100 Perugia, Italy, special grant IPRA, subproject no. 1. Paper no. 1931.

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Copyright © 1989. Crop Science Society of America, Inc.Copyright © 1989 by the Crop Science Society of America, Inc.

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