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Agronomy Journal Abstract -

Calcium Stimulation of Ammonium Absorption and Growth by Beet


This article in AJ

  1. Vol. 86 No. 5, p. 916-920
    Received: May 10, 1993

    * Corresponding author(s):
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  1. L. B. Fenn ,
  2. R. M. Taylor and
  3. C. M. Burks
  1. Texas Agric. Exp. Stn., Texas A&M Univ., 1380 A&M Cir., El Paso, TX 79927



Inefficiency in N use by plants contributes to environmental degradation. We examined the use of Ca2+ as a means of increasing NH+4 absorption in beet (Beta vulgaris cv. Detroit dark red). Ammonium absorption was measured in greenhouse and field studies. In the greenhonse, beet plants received full-strength nutrient solutions with Ca2+: NH+4 molar ratios (MR) of 0, 0.25, 0.5 and 1.0 (Ca2+:NH+4) and a NO-3 check. Absorption of 15NH+4 was monitored over a 30-h period. The field production trials occurred over 3 yr on a calcareous Saneli silty clay loam [clayey over sandy or sandy-skeletal, montmorillonitic (calcareous), thermic Vertic Torrifluvent]. The 15NH+4 absorption study showed the greatest plant weight at the molar ratio (MR) of 1.0 in tops (except in seedlings) and at 0.5 in bulbs. In seedlings, a biomass reallocation occurred in the root-bulbs from the tops. In both the intermediate and mature growth stages the weight of roots, tops and bulbs greatly increased. In the 15NH+4 absorption studies N concentrations were unchanged or decreased as the Ca2+ concentrations increased, but total N increased. Seedling bulb-root weight increases were apparenlly metabolite transfer from tops. The intermediate and mature beet plants showed increases in total N. In the greenhouse growth test, vegetative matter increased in excess of 300% at the MR of 0.5 over the check (MR:0). Growth of beet in the 0.5 MRtr eatment exceeded that on the NO-3 comparison by 14%. In field testing at a MR of 0.25 (CaCl2:urea), yields increases averaged 26% over 3 yr when compared with urea alone.

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