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This article in CS

  1. Vol. 10 No. 3, p. 280-285
    Received: Oct 8, 1969

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Relationship of Nitrate Reductase Activity to Grain Protein Production in Wheat1

  1. Lavoy I. Croy and
  2. R. H. Hageman2



Studies were conducted with field grown wheat (Triticum aestivum L.) with and without supplemental nitrogen to determine if nitrate reductase activity could be correlated with water soluble leaf protein, grain and grain protein (% and total) production. Nitrate reductase activity, nitrate, and water soluble leaf protein were determined at intervals throughout the life cycle of ‘Ponca’ and ‘Monon’ hard and soft red winter wheats, respectively. The major conclusions are, (a) nitrate content of the tissue was a major factor in controlling the level of enzyme activity; (b) nitrate reductase activity was related, though not numerically, to leaf protein content; (c) induction of nitrate reductase on a field scale, was achieved by supplemental nitrogen; (d) increased enzyme activity from supplemental nitrogen treatments was associated with increases in gram protein (% or total); (e) a significant correlation was found between the spring seasonal total of nitrate reductase activity (units of nitrogen reduced per hectare) and grain protein (kg/h) for both varieties; (f) this correlation is valid only for a specified genotype as Ponca required a higher level of enzyme activity to accumulate a unit of grain protein than Monon and (g) this observation suggests that Monon is more efficient in transporting reduced nitrogen from the vegetation to the grain than Ponca. Thirty-two hard and soft red winter wheat varieties grown in a field nursery with low nitrogen fertility were evaluated for nitrate reductase activity; nitrate and water soluble leaf protein, grain and grain protein (kg/h) production. Average values of enzyme activity obtained from three fall and three spring samplings showed little variation among genotypes and no correlation with grain or grain protein production. However, selection of 16 of the varieties exhibiting highest nitrate reductase activity on November 12, when nitrate was in adequate supply, would have included 9 of the 13 varieties which ultimately produced significantly higher grain protein (kg/h).

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