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

Abstract

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‐.

Effect of planting date, ventilation and soil temperature on growth and nutrition of tomato in high tunnels

“…In a factorial experiment, shoot growth was related to irradiance and average air temperature more than to soil temperature or particular day or night temperatures (Harssema, 1977). Under controlled conditions, soil cooler than 12°C reduced shoot N concentration, but it remained at 80% or more of that in plants grown in warmer soil (Ganmore-Neumann and Kafkafi, 1980;Cannell et al, 1963). Presumably this was a relatively small change because growth was inhibited as much as nutrient uptake.…”

Nitrate and ammonium as nitrogen sources for lupins prior to nodulation

“…In the many species which have been used to study the relative uptake of NO 3 and NH 4 (Cox and Reisenauer, 1973;Ganmore-Neumann and Kafkafi, 1980;Lycklema, 1963) both ions'are usually absorbed, although low temperatures favour NH 4 uptake (MacDuff and Hopper, 1986). Uptake of NH 4 should be favoured energetically over uptake of NO 3 (Raven and Smith, 1976;Haynes and Goh, 1978) while cation uptake (e.g.…”

Influence of root temperature on the potassium requirements of young tomato plants

“…Inspite of these adjustments it is evident that concentrations of mineral elements in plant tissues vary with the temperature of the root system (Ganmore-Neumann and Kafkafi, 1980;MacDuff et al, 1987). Such temperature dependence suggests that either the adjustments in morphology and capacity of ion uptake mechanisms are not regulated closely enough to maintain a constant concentration in tissues, or that requirements for nutrients change with temperature.…”