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Root Temperature and Percentage NO₃^–/NH₄⁺ Effect on Tomato Development II. Nutrients Composition of Tomato Plants¹

The possibility of supplying nutrients daily to tomato plants (Lycopersicum esculentum Mill.) grown in various seasons raised the question of the best percentage NO₃^-/ NH₄⁺ to be supplied to these plants. The effect of four (8, 16, 24, and 34 C) temperatures and four percentage NO₃^-/NH₄₊ (100/0, 75/25, 50/50, and 0/100) on the nutrient composition of tomato plants were studied. To obtain constant pH, percentage NO₃^-/NH₄₊ and temperature continuous flow technique was used. The solution was flushed through the pots at a rate of 1 liter/hour.

Increasing root temperature increased total-N, P, Mg, and K in the shoot irrespective of percentage NO₃^-/ NH₄⁺ in the solution. Calcium concentration increased in the shoot with increasing temperature only when the plants were fed with NO₃^- as the only source of N. The presence of NH₄^+> in the nutrient solution caused a decrease in Ca concentration in tomato plants grown in temperatures 16 C and above. Increase in the root temperature increased total-N and Ca, slightly increased P, and decreased Mg and K. Increasing root temperature increased N-N0₃^- concentration in the shoot, while decreasing it in thc roots. Low root temperature caused accumulation of N-NO³_- and K in the roots. It is suggested that the hindering of translocation of these ions at low temperature is one of the factors that slows down growth of tomato plants fed with nutrient solution containing a high ratio of NO₃^-.

Key Words: Calcium • Magnesium • Nitrate • Potassium Phosphate • Concentration of nutrients • Ammonium toxicity

² Division of Soil Chemistry and Plant Nutrition, Inst. of Soils and Water, ARO. The Volcani Center, Bet Dagan, Israel.

Received for publication December 13, 1978.

This article has been cited by other articles:

				M. P.N. Gent and Y.-Z. Ma Mineral Nutrition of Tomato under Diurnal Temperature Variation of Root and Shoot Crop Sci., November 1, 2000; 40(6): 1629 - 1636. [Abstract] [Full Text] [PDF]