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Monica Ozores-Hampton, Eric Simonne, Fritz Roka, Kelly Morgan, Steven Sargent, Crystal Snodgrass, and Eugene McAvoy

-irrigated tomato on plant nutritional status, marketable yield and distribution, and post-harvest quality; and 2) determine the economically optimal rate of N fertilization and analyze the sensitivity of N application rates to market conditions, specifically the

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T.K. Hartz, E.M. Miyao, and J.G. Valencia

Diagnosis and Recommendation Integrated System (DRIS) norms were derived for processing tomato (Lycopersicon esculentum Mill.) from a 1993-94 survey of >100 fields in the Sacramento and San Joaquin Valleys of California. Relative foliar N, P, K, Ca, Mg, and S concentrations were expressed in ratio form, with DRIS norms calculated as the means of fields with fruit yield ≥90 Mg·ha-1. Norms were developed for three growth stages: first bloom, full bloom, and 10% of fruits ripe. Optimum foliar nutrient concentration ranges were calculated by regression analysis from DRIS nutrient indices of high-yield fields. These optimum ranges were in general agreement with existing empirically derived sufficiency ranges for N and P, higher for Ca, Mg, and S, and much lower for K. The relatively low foliar K levels observed were attributed primarily to the strongly determinate growth habit of currently used cultivars. In the fields sampled, yield-limiting nutrient deficiency appeared to be rare.

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Warren C Stiles and Michael Rutzke

A total of 3850 leaf samples from commercial apple orchards located throughout New York State were submitted for analysis during the 1989-1992 seasons. These included 2583 samples from mature, 968 from young bearing age, and 299 from young nonbearing orchards. Percentages of samples (all ages and all varieties combined) found to be below currently recommended levels were: Zn 75%, Cu 74%, B 68%, Ca 63%, K 60%, Mg 60%, Mn 38%, Fe 19%, N 15%, and P 8%. Percentages of samples found to be above currently recommended levels were: N 21%: Zn 16%, Mn 13%, K 6%, B 4%, Mg 2%, Cu <1 %, and P <l %. Major problems consist of shortages of Zn, Cu, B, Ca, K, and Mg in 60% or more of all samples analyzed. Seasonal, varietal, pest management program, and tree age effects were apparent in the results, indicating that these factors must be considered in interpreting results of leaf sample analyses into recommendations for fertilization programs.

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T.K. Hartz, E.M. Miyao, and J.G. Valencia

Diagnosis and Recommendation Integrated System (DRIS) norms were derived for processing tomato (Lycopersicon esculentum Mill.) from a 1993-94 survey of >100 fields in the Sacramento and San Joaquin Valleys of California. Relative foliar N, P, K, Ca, Mg, and S concentrations were expressed in ratio form, with DRIS norms calculated as the means of fields with fruit yield ≥90 Mg·ha-1. Norms were developed for three growth stages: first bloom, full bloom, and 10% of fruits ripe. Optimum foliar nutrient concentration ranges were calculated by regression analysis from DRIS nutrient indices of high-yield fields. These optimum ranges were in general agreement with existing empirically derived sufficiency ranges for N and P, higher for Ca, Mg, and S, and much lower for K. The relatively low foliar K levels observed were attributed primarily to the strongly determinate growth habit of currently used cultivars. In the fields sampled, yield-limiting nutrient deficiency appeared to be rare.

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C.A. Sanchez, G.H. Snyder, and H.W. Burdine

Diagnosis and Recommendation Integrated System (DRIS) norms were derived for crisphead lettuce (Lactuca sativa L.) from field fertility experiments conducted over the past 20 years on mineral and organic soils in Florida. Preliminary testing indicates that DRIS diagnoses generally agree with diagnoses using the sufficiency range approach, with the advantage of predicting the degree of nutrient limitation. DRIS also appeared to correctly predict a response to K where sufficiency ranges currently used did not. Overall, DRIS appears to be a useful adjunct to the sufficiency range approach currently used to diagnose nutritional deficiencies in crisphead lettuce.

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Eric A. Curry

With the development of improved postharvest technology, the shelf life of fruit and vegetables has increased dramatically in many parts of the world. Presently, dietary recommendations for these commodities are based on the bioavailability of essential nutrients at the time of optimum harvest. Few people, however, are fortunate enough to have available freshly harvested produce all year and, therefore, must consume fruit and vegetables that have been stored under the best conditions available. The question, then, is whether nutritional quality changes with storage method and length. Little is known concerning the effects of storage on nutrient content or bioavailability. Furthermore, if levels of these antioxidants do indeed change, perhaps dietary recommendations should reflect this as well. The data in this study indicate that there are significant changes in the levels of natural antioxidants in two apple cultivars at harvest and after an extended period in cold storage.

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Seong-Hee Lee, Soon-Ho Ha, and Gap-Chae Chung

In order to diagnose the nutritional disorders caused by various environmental stress, biochemical test, xylem sap analysis and colorimetric petiole analysis were used to assay symptoms well before the severe development. Among the various enzymatic analysis, alkaline phosphatase activity was highly specific to calcium deficiency while in vivo nitrate reductase activity was not stable parameter in response to nitrogen deficiency. Determination of nitrogen, phosphorus and magnesium by colorimetric petiole analysis was sensitive to induced deficiencies. The status of potassium in the plant, however, could be better determined with the xylem sap analysis. Salinity stress induced by low osmotic potential of the nutrient solution increased the activity of alkaline phosphatase, showing similar results as calcium deficiency. Magnesium and phosphorous contents by the colorimetric petiole analysis were particularly low when the roots in anoxia.

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Raul I. Cabrera and Diana R. Devereaux

Containerized crape myrtle (Lagerstroemia indica L. × Lagerstroemia fauriei Koehne `Tonto') plants were grown for 9 months under various nitrogen fertility regimes, and then transplanted to a sandy loam soil with minimal management to evaluate their landscape establishment and growth performance. During the nursery phase plants were irrigated, except over an overwintering period, with complete nutrient solutions differing in applied N concentration, ranging from 15 to 300 mg·L-1. By 16 weeks after transplanting (WAT) into the landscape soil, plant biomass was significantly higher in the plants that had been grown with higher N supplies and had been among the smallest at transplant. Such plant growth response was linearly and positively correlated to plant N status at transplant. Plant shoot to root ratio and tissue N, Ca, S, and Fe concentrations, which had been significantly affected by the N fertilization regime in the nursery, equalized over time after transplant, with no significant differences observed among treatments by 16 WAT. Flowering response in the landscape was delayed in plants originally grown with the higher N supplies. Plant survival and establishment per se were not affected by treatments; no plants were lost, and aside from the differences in size and flower timing, all plants were considered aesthetically similar.

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Giorgio Gianquinto, Francesco Orsini, Paolo Sambo, and Matilde Paino D'Urzo

nutritional status of a crop at plant level. Monitoring crop nitrogen requirements through the assessment of plant nutritional status Plant measurements represent promising ways for monitoring crop nitrogen requirements throughout the growing season and for

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Cheng Bai, Charles C. Reilly, and Bruce W. Wood

Ni nutrition indicates that the translocating forms of reduced N in spring xylem sap of pecan may be affected by Ni deficiency. We hypothesize that 1) endogenous Ni nutritional status affects the relative composition of reduced-N forms in early spring