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This article in CS

  1. Vol. 42 No. 4, p. 1075-1080
     
    Received: Feb 21, 2001


    * Corresponding author(s): b-burson@tamu.edu
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doi:10.2135/cropsci2002.1075

Effect of Pollination Time on the Frequency of 2n + n Fertilization in Apomictic Buffelgrass

  1. Byron L. Burson *a,
  2. Mark A. Husseyb,
  3. Jo M. Actkinsona and
  4. Gail S. Shaferc
  1. a USDA-ARS, Crop Germplasm Research Unit, 430 Heep Center, Texas A&M Univ., College Station, TX 77843-2474
    b Dep. of Soil & Crop Sciences, Texas A&M Univ., College Station, TX 77843-2474
    c Yoder Bros., Inc., Chualar, CA 93925

Abstract

Fertilization of an unreduced egg (2n + n) increases ploidy level and creates a new hybrid. It occasionally occurs in apomictic species but at a frequency too low to be a reliable method for genetic improvement. This investigation was undertaken to determine if 2n + n fertilization could be increased by early pollination. Six buffelgrass, Pennisetum ciliare (L.) Link [syn. Cenchrus ciliaris L.], accessions, five apomicts and one sexual, were self-pollinated and cross-pollinated with birdwoodgrass, P. ciliare (L.) Link var. setigerum (Vahl.) Leek, at 3, 2, 1, and 0 d before anthesis. The 2n + n progeny were identified by flow cytometry. DNA content (pg 2C−1) was determined for 1962 self-pollinated and 3072 cross-pollinated plants. Twenty-eight self- and 80 cross-pollinated plants had a higher DNA content and were products of 2n + n fertilization. The overall frequency of 2n + n fertilization when self- and cross-pollinated was 1.4 and 2.6%, respectively. For all protogynous intervals, the frequency ranged from 0 to 5.2% for self-pollinated plants and 0 to 8.2% for cross-pollinated plants. When self-pollinated, there was no correlation between time of pollination and recovery of 2n + n hybrids. When cross-pollinated, there was a linear relationship between time of pollination and number of 2n + n hybrids recovered. More 2n + n hybrids were recovered from crosses made 2 or 3 d before anthesis. Thus in apomictic buffelgrass, the frequency of 2n + n fertilization can be increased by pollinating early, and in apomictic species where sexual germplasm is not available, this approach has potential to produce new apomictic hybrids.

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Copyright © 2002. Crop Science Society of AmericaPublished in Crop Sci.42:1075–1080.