Search Results

You are looking at 11 - 20 of 20 items for

  • Author or Editor: G. E. Wilcox x
Clear All Modify Search

Abstract

Traditional methods of bulk handling mechanically harvested tomatoes in pallet bins were compared with handling in bulk trailer units. Substantially greater cost reduction resulted from the bulk trailer system; costs per ton to handle and transport mechanically harvested tomatoes in pallet bins averaged $4.59 compared to $1.86 under the bulk trailer system. Additional savings were realized from utilization of the equipment in the bulk trailer system with more than 1 mechanical harvesting unit.

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

Simulation modeling techniques were used to determine the influence of precipitation during the harvest season on the economic feasibility of harvest mechanization for tomatoes on 3 soil types. Harvest mechanization was impeded on clay loam and silt loam soils at average precipitation levels during the harvest season due to wet soils and less than potential economic returns were realized. Only sandy loam soils consistently permitted full realization of the economic benefits that accrue from harvest mechanization.

Open Access

Abstract

(2-Chloroethyl)phosphonic acid (ethephon) applied at 2.9 kg/ha to plants of tomato (Lycopersicon esculentum MilUwhen 20-30% of the fruit were ripe, did not appreciably affect pH, total acidity, exterior color of the fruit, or consistency of the processed products. Organoleptic analyses of tomato juice indicated no differences in flavor between samples from ethephon-treated and untreated fruit. Chromatographic separation of fruit carotenoids showed that treated fruit synthesized more lycopene than controls.

Open Access

Watermelon, Citrullus lanatus (Thunb.) Matsum & Nakai cv. Sugar Baby, were grown in the field as a fall crop in open-top chambers (OTC) in southwestern Indiana with either charcoal-filtered (CF) or nonfiltered (NF) air. Ozone and sulfur dioxide were continuously monitored in OTC and ambient air. There was a significant decrease in marketable yield by weight (19.9%, P = 0.05), percentage of marketable fruit by number (20.8%, P = 0.10), and total yield by weight (21.5%, P = 0.05) from plants grown in the NF air treatment compared with those grown in CF air. Ozone-induced foliar injury was significantly greater on plants grown under NF conditions. Ambient concentrations of 03 in southwestern Indiana caused foliar injury (P = 0.10) and significant yield loss to a fall crop of watermelons.

Free 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

Four greenhouse leaf inoculation methods for screening Japanese plum (Prunus salicina L. and hybrids) for resistance to Xanthomonas campestris pv. pruni (Smith) Dye were compared for repeatability, ability to differentiate among plant genotype responses, and correlations with field ratings. Clonally propagated trees were inoculated artificially in a greenhouse by immersing leaves in 2.5 × 108 cfu/ml inoculum (DIP), rubbing the adaxial side of leaves with a slurry of 2.5 × 108 cfu/ml inoculum and Carborundum powder (CARB), infiltrating leaves with 5 × 105 cfu/ml inoculum using a needle-less syringe (INFS), and infiltrating with 5 × 106 cfu/ml inoculum (INF6). No greenhouse method was superior in all assessment categories. The CARB method was most repeatable (t = 0.78) but had a low Spearman's correlation (rs = 0.29), indicating that greenhouse rankings did not correspond closely with field rankings. The INF6 method was unsuitable because it did not differentiate between plant genotypes. The DIP method appeared most suitable, having moderate repeatability (t = 0.46) for four observations per leaf and moderate Spearman's correlation with field performance (rs = 0.56). The INF5 method may be appropriate for identifying bacterial spot resistance that is associated with resistance in the leaf mesophyll.

Free access