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  • Author or Editor: G. E. Wilcox x
  • Journal of the American Society for Horticultural Science x
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Abstract

Total yield and percentage of ripe tomato fruit were significantly increased following single foliar applications of 0.84 lb. per acre (2-chloroethyl)phosphonic acid (ethephon). Maximum responses were noted at 14 days after treatment. Three tomato cultivars seeded on 3 dates responded similarly. Seventeen days after ethephon application at the 15 percent ripe fruit stage, useable ripe fruit yield was increased to more than 90 percent of the total fruit yield, compared to 59 percent useable ripe fruit for the control. The application of ethephon advanced harvest by 12 to 14 days, with an increase in useable ripe fruit yield of 5 to 10 tons per acre over the optimum potential of the normal ripening rate for single-harvest culture.

Open Access
Authors: and

Abstract

Tomato fruit accumulated nitrate when the controlled environmental conditions combined high temperature, high N fertilization level, and low light intensity. Nitrate accumulation in the fruit was preceded by a condition of low nitrate reductase activity and nitrate accumulation in the leaves. The processed product with high concentration of nitrate caused extensive detinning of internal can surfaces after 6 months’ storage at room temperature.

Open Access

Abstract

Growth and elemental uptake patterns in field-grown plants of tomato (Lycopersicon esculentum mill.) were determined from 21 days after emergence to harvest. Dry weight accumulation was linear after 56 days at 5.55 g/day-plant. Dry weight accumulation after 70 days was mainly as fruit, which accumulated at 4.9 g/day-plant. Nutrient accumulation per day after 70 days was 20 mg N, 2 mg P, 25 mg K, 120 mg Ca and 10 mg Mg in the vines, and 150 mg N, 21 mg P, 231 mg K, 6 mg CA and 10 mg Mg in the fruit. Thus, after 70 days about 90% of the N, P and K, 5% of the Ca and 32% of the Mg uptake was in the fruit.

Open Access
Authors: and

Abstract

Recently matured whole leaves of tomato Lycopersicon esculentum Mill cvs. Centennial and Knox) gave the most reliable indication of total N, while NO3-N in older mature leaf petioles better reflected N availability and absorption. The NO3-N content of petioles was more indicative of N status of the plant than total N analysis of whole leaves. The NO3-N and total N contents of leaf parts generally decreased with increasing maturity. Soil solution NO3-N concentration increased exponentially with increasing N application rates. The first 45 kg N/ha increments increased soil solution NO3-N concentration only 10 ppm whereas the fourth 45 kg N/ha increment increased NO3-N concentration 40 ppm. Ninety kg N/ha application produced a concentration of 48 ppm NO3-N that resulted in a nearly maximum petiole concentration of 14,500 ppm NO3-N, indicating that this NO3-N concentration provided sufficient available N for the immediate reserve requirements for plant growth.

Open Access

Abstract

Tomato plants ‘Campbell 1327’ grown in peat with NH4 nutrition had no visible symptoms of NH4 toxicity, while severe symptoms of NH4 toxicity were displayed in solution or sand culture. Growth of plants was much better with NO3-N than NH4-N in sand, vermiculite, or solution culture; but in peat, growth of NH4-treated plants equalled or exceeded that of NO3-treated plants in sand, vermiculite, and peat. The total dry weight of NH4-treated plants grown in peat was 2, 2.5, and 3.4 times higher than plants grown in vermiculite, sand, and solution culture, respectively. Content of uncomplexed ASHS.109.3.406 in NH4-treated plants grown in peat was reduced markedly compared with other media. NH4-treated plants grown in sand, vermiculite, and solution culture, displaying NH4 toxicity symptoms, had a total amino acid:free NH4 + molar ratio < 2, compared to 6-8 with NO3. For NH4-treated plants grown in peat the ratio was similar to that of NO3-treated plants. Asparagine and glutamine in NH4-treated plants grown in peat were 3.5 and 11.3 times higher than with NO3-N, indicating a high efficiency in detoxification of NH4 through incorporation into these amino acids. The medium on which a plant is grown can have a marked influence on the plant response to N form.

Open Access

Abstract

A shift from NO3 to NH4-N nutrition for tomato (Lycopersicon esculentum Mill.) plants resulted in a significant decrease in xylem exudation rate within 15 minutes. Ammonium treatment also decreased Ca and Mg concentration in exudate in the 1.5 to 2.5 hour interval after the shift, whereas free NH4 and amides increased in the same period. Potassium ion concentration did not change in the time interval from 15 minutes to 7 days following the change of N form. Reduced exudate concentration or reduced exudation rate resulted in large decreases in the total amount of K, Ca, and Mg delivered in the presence of NH4 relative to that of NO3, and offers a possible explanation for the observed deficiencies of these cations in shoot tissues of plants under conditions of NH4 toxicity.

Open Access

Abstract

The N form had a pronounced effect on the levels of free amino acids. When compared to NO3, NH4 brought about a several fold increase in free amino acids (dry basis) in the roots, while smaller increases were observed in mature, fully expanded leaves, in young growing leaves, and in tomato fruit. Plants fed a combination of the 2 N forms had intermediate levels. The pattern of response to NH4 indicated that aspartic and glutamic acids as well as their amides were predominantly snythesized in the roots when the N source was NH4. The site of synthesis shifted to the leaves when the N source was NO3. The amino acids arginine, serine, alanine, and γ-aminobutyric acid were predominantly synthesized in the leaves irrespective of N form. Topical application of Ca on fruit grown with NH4 resulted in amino acid levels in the fruit similar to those of NO3 fruit. Ammonium toxicity was found to be accompanied by large increases in the levels of GABA and serine in the leaves. It is suggested that ammonium toxicity is a manifestation of intracellular Ca deficiency.

Open Access

Abstract

Varying the level of added P to a deficient soil from 0, 25, 50, 75, 100, 200 and 400 ppm made it possible to study the influence of deficiency, sub-adequate, adequate and excess amounts of P on its distribution into P fractions within tomato leaves. Plant growth response was obtained at P rates up to 100 ppm. The P fractionation data indicated that inorganic phosphate constituted about one quarter of the total plant P even when the plant is deficient in P. The plant did not accumulate phosphate until it was supplied at rates that exceeded requirements of growth and then it was accumulated mainly as inorganic phosphate while the levels of soluble organic P, RNA-P, DNA-P, phospholipid-P and phosphorprotein-P remained unchanged over the entire range of P rates.

Open Access

Abstract

Ammonium nutrition reduced Ca and Mg composition of tomatoes but not peas in a study of NH4 and NO3-N influence at different Ca and Mg levels in solution and media pH adjustment.

Growth of shoot and root tissue of tomatoes and peas was reduced with NH4-N when pH of the medium was not buffered. Addition of dolomite increased growth of tomatoes with NH4-N equal to that with NO3-N.

The competitive effect of Ca and Mg in uptake by tomato plants with NO3-N was absent with NH4-N. Ammonium nutrition also eliminated competition uptake between Ca and Mg when pH was regulated with dolomite or with the addition of CaSO4.

The Ca and Mg composition of the tomato tops was reduced by NH4-N and was directly related to root composition. The Ca and Mg composition of the pea tops was the same with NO3-N or NH4-N while NH4-N reduced the Ca and Mg composition of the root tissue.

Open Access

Abstract

The performance of H-1350, H-1409, C-17, ‘Fireball’, and ‘Roma’ tomato transplants that received different clipping treatments at Tifton, Georgia, were evaluated at Lafayette, Indiana, and the Plant Industry Station, Beltsville, Maryland. Field-grown transplants were either left unclipped, control clipped (1 inch of growth was removed but the terminal bud was left intact), or moderately clipped (the terminal bud and flower cluster were removed).

Moderately clipped transplants of all 5 cultivars performed as well as non-clipped plants, but usable fruit yield was reduced by control clipping. At New Brunswick, New Jersey, fruit yields of the C-17 transplants moderately clipped at various intervals were reduced. In view of the other 2 tests and other recently published reports, moderate clipping appeared to have little effect on fruit yields in northern production areas.

Open Access