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The necessity of achieving appropriate nitrogen fertilization of vegetable crops relates to both economical and environmental sustainability. Split nitrogen applications have been shown to improve N-use efficiency, in line with the aforementioned objective and should therefore be encouraged. Given the variation in the amount of N naturally provided to, or uptaken by, the crop, strategies are required to tailor supplementary fertilization to actual crop needs, keeping in mind the absolute requirement for optimal yield in quality and quantity. It is suggested that the fertilization rates applied at sowing or later in the season can be figured in two manners. The first relies on modelling; the second on measurements. The modelling (N budget) approach, mostly linked to initiatives on the European continent, would be most applicable to the determination of the first fertilizer dressing. When a plant stand is established, however, canopy-based measurements made either directly or remotely could be developed to make use of the capability of the plants to integrate the properties of the soil environment and to decide upon further top-dressed applications. For this purpose, a fully fertilized “reference plot” has to be introduced in the field in order to overcome the variability induced by season, site and cultivar. With the emergence of “precision farming” and “remote sensing technologies” it is now possible to adjust fertilizer inputs not only at the field level but also within fields based on actual, localized requirements.

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The IR4 Specialty Crops Program was established to assist in the registration of pest control products for minor uses. The National program, headquartered at Rutgers University and operating through four regions with a network of scientists in every state, develops lists of grower needs, prioritizes projects and develops protocols to secure EPA tolerances that lead to labels. Every year IR4 works on pest control products needed by the vegetable industry. Pest control products being researched for 2006 include Club root and wire stem control in crucifers with Ranman and Moncut: Lep. Larvae control in beans with Avaunt and Rimon; Phytopthora capsici control in peppers and squash; weed control in tomatoes with Reflex, Goal, and Dual Magnum and powdery mildew control in cucurbits. Research Projects were discussed and updated.

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Overcoming environmental stresses during seedling establishment is crucial to successful vegetable production. In the irrigated production areas of the southwestern United States, stress most often is related to unfavorable temperature, soil or water salinity, or poor soil structure; it is frequently difficult to separate the effects of these stresses, since they may all be present to some significant degree. Growers use a variety of techniques to ameliorate these conditions. The use of sprinkler irrigation for stand establishment has become a widespread practice; sprinkling moderates soil temperature, minimizes salinity in the zone of germination, and reduces soil crusting. By modifying bed configuration, growers have been able to increase soil temperature to stimulate germination. Various chemical and physical treatments have proven effective in reducing soil crusting. The use of transplants has expanded for many crops, both as a means to circumvent seedling establishment problems and as a technique to obtain earliness.

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Abstract

Development of interplanting systems for vegetables has been impeded due to concerns about yield reductions and use of systematic experimental designs that limit analysis of fundamental competitive processes. This study employed an addition series and growth analysis combined with management strategies aimed at minimizing competition between the crop and the interplant. Pak choi [Brassica rapa L. (Chinensis Group)] was interplanted with strips of ryegrass (Lolium perenne L.) that covered 67% of the soil. Pak Choi was a weak competitor compared to perennial ryegrass. Mulch suppression using a sublethal rate of fluazifop provided the most promising management strategy to reduce competition from the ryegrass interplant. Timing of suppression and reduction of mulch root growth were critical elements of successful management. Chemical names used: (±)-2-[4-[[5-(trifluoromethyl)-2-pyrindinyI]oxy]phenoxy]propanoic acid (fluazifop).

Open Access

The composition of composts derived from municipal solid wastes can affect emergence and seedling growth. Composts consisting of biosolids and yard trimmings [standard compost (SC)] alone or with mixed waste paper (MWP), refuse-derived fuel (RDF), or refuse-derived fuel residuals (RDFR) were evaluated in seedling trays and pots for vegetable crop seedling emergence and growth. In trays, tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), and pepper (Capsicum annuum L.) seedlings emerged faster from a commercial peat-lite mix and from sandy field soil than from the composts. Plants were tallest and shoots were generally heaviest in the peat-lite mix and aged SC and smallest in the field soil. MWP compost generally inhibited early seedling growth more than RDF or RDFR composts. Among the composts, seedlings were tallest and heaviest in SC. In pots, growth of each vegetable was generally greatest in SC, followed by other composts, and lowest in sandy soil. Tomato and pepper seedling emergence was more sensitive to the inhibitory effects of the RDF, RDFR, and MWP composts than cucumber seedling emergence. Fertilizer increased plant growth in each medium except SC, in which cucumber stem diameter was not increased. Adding MWP, RDF, or RDFR to SC generally decreased seedling emergence and growth. The composts prolonged days to emergence and decreased percent emerged seedlings. However, subsequent seedling growth in composts was equal to or greater than seedlings in the peat-lite mix and much greater than those in the sandy field soil.

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Growth-chamber studies were conducted to examine the ability of seven vegetable crops-`Blue Lake' bean (Phaseolus vulgaris L.), `Detroit Dark Red' beet (Beta vulgaris L.), `Burgundy' okra (Abelmoschus esculentus (Moench), `Little Marvel' pea (Pisum sativum L.), `California Wonder' bell pepper (Capsicum annuum L.), `New Zealand' spinach (Spinacia oleracea L.), and `Beefsteak' tomato (Lycopersicon esculentum Mill.)–to adjust osmotically in response to water-deficit stress. Water stress was imposed by withholding water for 3 days, and the adjustment of leaf and root osmotic potentials upon relief of the stress and rehydration were monitored with thermocouple psychrometers. Despite similar reductions in leaf water potential and stomata1 conductance among the species studied, crop-specific differences were observed in leaf and root osmotic adjustment. Leaf osmotic adjustment was observed for bean, pepper, and tomato following water-deficit stress. Root osmotic adjustment was significant in bean, okra, pea, and tomato. Furthermore, differences in leaf and root osmotic adjustment were also observed among five tomato cultivars. Leaf osmotic adjustment was not associated with the maintenance of leaf growth following water-deficit stress, since leaf expansion of water-stressed bean and pepper, two species capable of osmotic adjustment, was similar to that of spinach, which exhibited no leaf osmotic adjustment.

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Overcoming environmental stresses during seedling establishment is crucial to successful vegetable production. In the irrigated production areas of the southwestern United States, stress most often is related to unfavorable temperature, soil or water salinity, or poor soil structure; it is frequently difficult to separate the effects of these stresses because they may all be present to some significant degree. Growers use a variety of techniques to ameliorate these conditions. Advances in seed technology have improved seedling establishment under unfavorable temperatures, particularly for lettuce. The use of sprinkler irrigation for stand establishment has become a widespread practice; sprinkling moderates soil temperature, minimizes salinity in the zone of germination, and reduces soil crusting. By modifying bed configuration, growers have been able to increase soil temperature to stimulate germination. Modifying seed placement and furrow irrigation patterns can create zones of lower salinity. Various chemical and physical treatments have proven effective in reducing soil crusting. The use of transplants-has expanded for many crops, both as a means to circumvent seedling establishment problems, as well as a technique to obtain earliness.

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Abstract

Field experiments were conducted to test the emergence, early growth, and salt build-up in soil and leaves with 5 vegetable crops germinated by sprinkle and trickle irrigation using saline water. In some of the crops (cucumber, tomato, pepper) trickle irrigation shortened the time until emergence and the stand was more uniform. Other crops (muskmelon, onion) responded in a similar manner to both irrigation methods. Seedling development was good with both methods. Trickling produced a higher salt concn in the 0 to 3-cm soil layer of the crop row, although this had no apparent effect on emergence, seedling wt, or chloride content of the leaves.

Open Access

Broccoli, potatoes, cucumbers and green peas were fertilized respectively with 241, 168, 168 and 28 kg N ha-1. The N accumulation was equivalent to the fertilizer application rates for the broccoli, potatoes and cucumbers while the peas accumulated 321 kg N ha-1. Vegetable yields were not affected by previous cereal rye cover crops when compared to the fallow control. Cover crops following broccoli accumulated the least and peas the most N. Inorganic N in the top 30 cm at harvest were significantly different between vegetables, but not in the 30-60 cm depth.

Chicken manure and ammonium nitrate as N sources were compared. Broccoli was the test crop and was fertilized with both sources at 241 kg N ha-1. Broccoli yields and N accumulation were different between sources of N and between N and no-N treatments. Inorganic N leaching was greatest with ammonium nitrate fertilization and chicken manure was similar to the no-N fertilizer treatment.

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often increased vegetable yields, combining biosolids and mineral fertilizers was generally more effective than biosolids alone. Several studies of commercial cereal crops have reported negative or neutral yield responses to application of paper sludge

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