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

Abstract

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.

Effect of Different Spacing and Urea Application Rates on Fruit Nutrient Composition, Growth and Yield of Tomato in Derived Savannah Vegetation of Kogi State, Nigeria

“…[26] [27] found that tomato seedlings grown with high N levels had enhanced growth and survival after transplanting. [28] Reported fertilizer containing nitrogen increases vegetative growth of tomato. Among the urea rate and intra spacing interaction effects, tomato spaced at 30 cm with no urea application produced the least number of branches and leaves, while the most produced branches and leaves occurred in plots with 50 cm intra spacing and 108.6 kg/ha urea fertilizer at both locations.…”

Tomato yield and quality as affected by nitrogen source and salinity

“…Fertilizers containing both NO 3 -and NH 4 + are generally recommended for tomato production because vegetative growth is maximized, which is thought to increase fruit yield [10]. Ammonium, as the sole N-source, decreased plant growth with respect to nitrate-fed plants [20].…”

“…growth than when either N-form was used alone [10]. Few studies have been done with NO 3 -and NH 4 + combinations in order to determine their effect on tomato yield.…”

Development of “stem-topple” disorder inRanunculus asiaticusis related to localised disturbances in tissue calcium levels

“…Increased NH 4 + supply, or NH 4 :NO 3 ratio, were demonstrated to reduce cation, (especially K, Mg, and Ca) uptake and levels in the organs of several plants, probably as a result of increased NH 4 + uptake through a charge balance mechanism in ion uptake (Ganmore-Neumann and Kafkafi, 1980;Marti and Mills, 1991;Bar-Tal et al, 2001b).…”