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Agronomy Journal Abstract -

Root Temperature and Percentage NO3-/NH4+ Effect on Tomato Plant Development I. Morphology and Growth1


This article in AJ

  1. Vol. 72 No. 5, p. 758-761
    Received: Dec 13, 1978

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  1. Ruth Ganmore-Neumann and
  2. U. Kafkafi2



The increased use of combined irrigastion and fertilization under field conditions, and the possibility of sup plying nutrients to the plants daily raised the problem of the best percentages NO3-/NH4+ to be supplied to tomato plants (Lycopersicum esculentum Mill) grown in the field in the various seasons. The objectives of this work were to find the most suitable percentages of NO3-/NH4+ at various root temperatures, on growth and morphology of tomato roots.

Tomato plants were grown in an experiment with a factorial design of four temperatures (8, 16, 24, and 34 C) and four percentages NO3-/NH4+ (100/0, 75/25, 50/50, and 0/100) at constant N concentration of 10 meq/liter and constant pH of 6.5. To maintain the percentage NO3-/NH4+ and pH constant, the nutrient solution was flushed through the pots at a rate of 1 liter per hour. When constant pH and constant solution composition were maintained the 50/50 NO3-/NH4+ treatment showed the most growth, averaged over all temperatures. High percentage NO3-/NH4+ retarded plant growth at low root temperatures but is preferred at high root temperature. Plants grown in solution rich in NO3- developed long, thin branched roots and those grown in solution rich in NH4+ developed short, thick second and third order roots.

The results of this work can be directly applied to hydroponic systems and with a future field study it may produce new fertilizer solution compositions to be adapted to specific soil environmental conditions.

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