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  • Author or Editor: Allen V. Barker x
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Studies of ethylene evolution by tomato (Lycopersicon esculentum Mill.) fruit were conducted with plants receiving NH4-N or NO3-N nutrition. Fruit of plants grown with NH4-N had a higher occurrence of blossom-end rot (BER), higher NH4-N concentrations, and higher ethylene evolution rates than fruit from plants grown with NO3-N. Fruit of plants grown with NO3-N showed no enhancement in ethylene evolution with BER development. Fertilizing these plants with Ca(NO3)2 doubled the average Ca concentration of fruit and restricted BER development. Ammonium suppressed Ca accumulation in fruit relative to those grown with NO3-N. Ethylene evolution increased as fruit from plants receiving NO3-N ripened, but without a concomitant increase in NH4-N concentrations in the fruit. Ammonium accumulation in fruit induced BER and enhanced ethylene evolution. These relationships were unique, for NH4-N accumulation did not seem to be a naturally occurring phenomenon in ripening fruit or in fruit that have BER arising from other causal factors.

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Composts of agricultural by-products (chicken manure and cranberry pomace), biosolids and woodchips, biosolids mixed municipal solid wastes, and autumn leaves were evaluated for production of turfgrass or wildflower sods. The best sods measured by establishment and growth of stands were in the agricultural compost, which was rich in N (avg. 1.7%) and low in NH4 + (avg. 135 mg N/kg). High NH4 + limited stand establishment with immature biosolids-based composts. Some of these immature composts had total N concentrations >2%. Leaf compost was too low in total N (<0.7%) to support sod production without supplemental fertilization. Aging of each compost improved its capacity to support sod production, apparently as a result of changes in the N status of the media. Growth of soilborne weeds was promoted by incorporation of composts into soil or by application of composts as mulches. A barrier mulch of paper or other materials that impeded weed emergence effected weed control. Use of a mature compost with adequate N and control of weeds are essential practices for sod establishment with composts. E-mail barker@pssci.umass.edu

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Abstract

Seedlings of 5 strains of tomato (Lycopersicon spp.) were grown in low-Ca nutrient solutions in a greenhouse for 4 weeks in order to determine whether Ca-efficient and inefficient strains differed in concentrations of water-soluble Ca. Aqueous extracts from dried tissues of efficient strains were lower in percent of Ca and in electrical conductivity than were extracts from inefficient strains. Efficient strains may suffer less than inefficient strains from precipitation or displacement of Ca from functional sites in tissues by other ions.

Open Access

An agricultural compost of chicken manure and cranberry pomace, a municipal compost of biosolids and mixed municipal solid wastes, and a compost of autumn leaves were evaluated for production of turfgrass sods and wildflower sods. Composts made during the year of the experiment and one-year-old composts were compared. The experiment was conducted outdoors with composts layered on sheets of plastic laid on the soil surface. The sheets of plastic controlled soil-borne weeds and facilitated harvest of sods. The best sods measured by stand and growth were produced with the agricultural compost, which was rich in N (avg. 1.7%) and low in NH4+ (avg. 135 mg/kg). High NH4+ (>900 mg/kg) appeared to limit stand establishment with the fresh municipal compost. The leaf compost was too low in N to support sod growth without fertilization. Aging of each compost improved its capacity to support sod production, apparently as a result of changes in the N status in the media.

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Management of vegetation is an important element of roadside maintenance for safety and aesthetics. Current methods of management by highway departments principally involve mowing and the use of conventional, chemical herbicides. This research addressed use of herbicides (citric acid, clove oil, corn gluten meal, and pelargonic acid) that are considered as alternatives to conventional herbicides and the use of mechanical treatments of woodchip and bark mulches and burning. These alternative methods were compared with the use of conventional herbicides to assess the relative efficacy of treatments on roadside sites. A single application of pelargonic acid demonstrated immediate or short-term suppression of growth of vegetation; however, the efficacy lasted for no more than 6 weeks, after which regrowth was not distinguishable from untreated vegetation. Repeated applications of pelargonic acid will be necessary for season-long efficacy. Formulations of citric-acetic acid gave no control or only weak suppression of vegetative growth soon after application, and no suppression was evident after 6 weeks, suggesting that these materials have only limited use in roadside environments. The effects of burning lasted for about 6 weeks. No suppression of growth of roadside vegetation occurred with the use of corn gluten meal, which acted as a nitrogen fertilizer to promote growth. Mulches of bark or woodchips were strongly suppressive against emerging vegetation for 2 years, but were more effective in the first year than in the second year after application. The costs of materials and labor for the alternative practices were substantially more than for the conventional herbicides used in this study.

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This research evaluated production of wildflower sods in soil and composts of mixed municipal solid waste, biosolids and woodchips, fall leaves, and mixed agricultural wastes. Soil or composts were laid on plastic sheeting in outdoor plots, and a mixture of wildflower seeds was sown in July and in September in separate experiments. Quality of sods was assessed in two growing seasons. Best sods with respect to seed germination, stand establishment, and intensity and diversity of bloom over two seasons occurred in mature biosolids compost and in agricultural waste compost. These composts were low in ammonium but rich in total N. Germination and growth of wildflowers were limited by high ammonium concentrations in immature biosolids composts. Nitrogen deficiency limited sod growth and quality in leaf composts. Poor N nutrition and weed competition restricted sod production in soil. Fertilization of soil promoted unacceptably large weed growth. Summer seeding or fall seeding resulted in good sods, but many annual flowers that appeared in the summer seeding were absent in the fall-seeded planting. Using plastic-lined plots was a convenient system for evaluating composts and other media in outdoor culture.

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Abstract

Nitrapyrin, etridiazol, fenaminosulf, sodium azide, and a formulated product of aromatic substances and alkenes were evaluated as nitrification inhibitors under greenhouse conditions for radish (Raphanus sativus L. ‘Cherry Belle’) fertilized with sewage sludge. Nitrapyrin and etridiazol inhibited nitrification, but their use restricted plant growth and lowered the Ca and Mg concentrations of the plants. Nitrification was inhibited slightly by fenaminosulf, which had little effect on plant growth and composition. Sodium azide and the formulated product were not effective as nitrification inhibitors. The azide was phytotoxic, but the formulated product had no toxic effects on growth. The toxic effects of chemicals with efficacy as nitrification inhibitors were due largely to the accumulation of NH4-N in the medium. Chemical names used: 2-chloro-6-(trichloromethyI)pyridine (nitrapyrin); 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole (etridiazol); and sodium p-(dimethylamino)benzenediazosulfonate (fenaminosulf).

Open Access

Abstract

Spinach, Spinacia oleracea, L., cv. America, Heavy Pack, and Hybrid 424 were grown in sand culture with variable NO3 concentrations from 0.187 to 48 meq/l. The cultivars were representative of savoyed, semisavoyed, and smooth-leaf types, respectively. The plants were harvested when those cultured at 12 and 18 meq NO3/l had obtained approximate market maturity. At this time an array of deficiency, sufficiency, and toxicity symptoms were evident. Great differences in NO3 accumulation and critical NO3 concentrations occurred among cultivars. Critical NO3-N concentrations for the whole leaves of spinach plants were: ‘America’, 0.17%, ‘Heavy Pack’, 0.15%, and ‘Hybrid 424’, 0.045% of their dry weights. Calculations relating spinach consumption and impaired human health suggest that adult health should not be affected even with massive ingestion of spinach.

Open Access

Abstract

Brussels sprouts (Brassica oleracea var. gemmifera, Zenker) were grown in sand culture at variable Ca levels in the greenhouse. More Ca accumulated in leaves than in sprouts. With plant growth restricted by late seeding and low greenhouse temp, typical Ca deficiency symptoms occurred on the growing points of plants cultured at low Ca levels, but internal browning did not occur. When growth was enhanced by cultural modifications, sprout internal browning occurred at low Ca levels and decreased as Ca levels were increased. The incidence of internal browning was related to low Ca concn in sprouts.

Open Access

Abstract

The accumulation of cations and NO3-N was higher in cucumber shoots than in pea shoots grown on nitrate nutrition. Total N concn in shoots did not differ between the species. Ammonium nutrition suppressed cation accumulation in cucumbers but not in peas. Differences in cation accumulation in the shoots are attributed to the form in which N is translocated from root to shoot.

Open Access