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This article in CS

  1. Vol. 42 No. 6, p. 2044-2048
    Received: May 1, 2001

    * Corresponding author(s): belangergf@agr.gc.ca
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Phosphorous Uptake and Concentration of Timothy Genotypes under Varying N Applications

  1. G. Bélanger *,
  2. A. Brégard and
  3. R. Michaud
  1. Agriculture and Agri-Food Canada, 2560 Hochelaga Bd., Sainte-Foy, QC, G1V 2J3 Canada


Improving P uptake in timothy (Phleum pratense L.) would reduce excess soil phosphate while producing forage with greater P nutritional value. A strong relationship exists between N and P concentration in plants, and we hypothesized that genotypes characterized for contrasting N concentration or uptake may also exhibit contrasting P concentration and uptake. Two timothy populations derived from divergent selection for high and low forage N concentration were studied in Experiment 1. These two populations were also studied in Experiment 2, along with seven half-sib families identified in a field study as having contrasting dry matter (DM) yield and N concentration. In both experiments, a reference population, ‘Champ’, was included and plants were grown in a growth room with varying N rates. Independent of applied N, the genotypes differed for P concentration, P uptake, and P to N ratio (P/N), in forage and total biomass, as well as for leaf P concentration, leaf weight ratio (LWR), root weight ratio (RWR) and efficiency of P uptake for each unit of root biomass (PUPEroot). Averaged across N rates in Experiment 2, forage P concentration among genotypes ranged from 4.1 to 5.1 g P kg−1 DM, while forage P uptake ranged from 10.0 to 14.6 mg P per plant. Variations in P uptake and concentration were related to genotypic differences in DM yield, leaf P concentration, LWR, and RWR. Phosphorus concentration and uptake decreased under N stress. We conclude that variation exists among timothy genotypes for P concentration and uptake.

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Copyright © 2002. Crop Science Society of AmericaPublished in Crop Sci.42:2044–2048.