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Agronomy Journal Abstract -

Nitrogen and Dry Matter Accumulation, Remobilization, and Losses for Mediterranean Wheat during Grain Filling

 

This article in AJ

  1. Vol. 83 No. 5, p. 864-870
     
    Received: May 14, 1990


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doi:10.2134/agronj1991.00021962008300050018x
  1. Despo K. Papakosta  and
  2. A.A. Gagianas
  1. Lab. of Agronomy, School of Agric., Aristotle Univ. of Thessaloniki, GR-54006 Thessaloniki, Greece

Abstract

Abstract

Dry matter and N accumulated by winter wheat (Triticum spp.) plants until anthesis are of importance under a Mediterranean climate because yield greatly depends on translocation of pre-anthesis assimilates to grain. This field study was conducted to assess the effect of N fertilizer and cultivar on the amount of pre-anthesis dry matter and N accumulated and remobilized, and the possible N losses. Two bread (T. aestivum L.) and two durum (T. durum Desf.) wheat cultivars were grown in a silty clay (Typic Xerorthent) in 1986 and 1987. Nitrogen at a rate of 150 kg ha−1 was applied before planting or 100 kg N ha−1 was applied before planting and then 50 kg N ha−1 at early boot stage. Cultivar dry matter translocation efficiencies ranged from 2.3 to 36.4%, N-translocation efficiencies from 60.9 to 80.7%, and the contribution of pre-anthesis assimilates to grain from 6 to 73%. Split N application reduced the contribution of pre-anthesis assimilates to grain. High amounts of N (>200 kg ha−1), which had accumulated by anthesis led to net N losses at maturity, even with high yields (>6 Mg ha−1). No N losses were observed when N content at anthesis was lower than about 150 kg ha−1. However, at values ranging between these upper and lower limits, N loss was yield dependent (only yields >8 Mg ha−1 prevented N losses). Split N application tended to reduce N losses. Results indicated that the greater the amount of dry matter and N accumulated before anthesis, the higher the translocation rates of dry matter to grain and the greater the risk of net N losses at maturity.

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