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Agricultural producers in the United States require timely and accurate information on critical issues, environmental crises, and best management practices to make effective production decisions and to remain competitive in a global economy. Sources of information (university departments, extension, industry, consultants, scientific and trade publications) often take a single discipline approach that makes it difficult for growers to process and utilize information effectively. The high cost of printed publications make frequent updates impractical, while rapidly changing technologies and issues demand continual publication changes and updates. The rapid development and peer review of multi-discipline, research based information is possible through computer information transfer technology. The Univ. of California's Vegetable Crops Research and Information Center (VRIC) has developed a new World Wide Web site to disseminate peer-reviewed fact sheets, research results, updated publications, and multi-media educational resources relating to critical issues, best management practices, postharvest handling, and marketing of vegetable crops. The website disseminates multi-discipline information originating from the Univ. of California, the USDA, and cooperating agencies and universities. The VRIC website proactively sends peer-reviewed critical issue fact sheets to selected news media, government, industry, and academic contacts. These fact sheets help personnel frequently contacted by the media during crises to answer questions effectively. The website directs visitors to additional agricultural information resources and contains information on careers and educational opportunities available in the field of vegetable crops.
Abstract
Cranberry plants, Vaccinium macrocarpon Ait. ‘Stevens’ were grown in nutrient solutions with several levels of NH4-N and NO3-N alone and in combination. The nutrient solutions were sampled weekly and analyzed for concn of NO3-N and NH4-N. It was found that the plants absorbed NH4-N preferentially to NO3-N. Dry wt and number of new shoots produced were strongly favored by the NH4 form of N. Tissue N concn was low and the plants were N-deficient when the NH4-N was depleted from the nutrient solutions before termination of the experiment, and concn was high with a sustained NH4-N supply. Plants grown in NO3-N solutions were N-deficient and had tissue N concn interm ediate to those for the extreme levels of NH4-N. No NO3-N was detected in the plant tissues. Nitrate reductase activity was absent from the aboveground portions of the plants when the possible effect of microorganisms were removed. It is concluded that NH4-N is essential for cranberry growth.
The Univ. of California's Vegetable Crops Research and Information Center (VRIC) has developed a new World Wide Web site that allows the rapid development and peer review of multi-discipline, research-based information. The VRIC website (http://vrichome.ucdavis.edu) disseminates peer-reviewed fact sheets, research results, updated publications, and multi-media educational resources relating to critical issues, best management practices, postharvest handling, and marketing of vegetable crops. The website disseminates multi-discipline information originating from the Univ. of California, the USDA, and cooperating agencies and universities. The VRIC website proactively sends peer-reviewed critical-issue fact sheets to selected news media, government, industry, and academic contacts. These fact sheets help personnel frequently contacted by the media during crises to answer questions effectively. The website directs visitors to additional agricultural information resources and contains information on careers and educational opportunities available in the field of vegetable crops.
One-year-old `Fuji' apple trees on six rootstocks (Mark, M.9, M.26, M.7A, MM.106, and MM.111) were compared for N and water uptake and utilization. The trees were potted in sand and subjected to a 75-day N-deprivation period (supplied with modified Hoagland's solution lacking N) to deplete their N reserves. Thereafter, they were supplied with a complete modified Hoagland's solution. Uptake of water and N differed by rootstock. Water and N uptake were positively related to tree dry weight (r = +0.97, P = 0.001). Trees that had the highest N concentrations at planting were the last to set bud during the N-deprivation-phase. Tree size after one growing season depended largely on rootstock girth and whole-tree-Nconcentration at planting (r 2 = 0.80, P = 0.0001) regardless of rootstock. Water and N uptake efficiency (liter of water or mg N absorbed per g root dry weight, respectively) differed among the rootstocks, being highest for trees on MM.111 and lowest for trees on M.7A rootstock. Nitrogen and water utilization efficiency (g dry weight gained per mg N or per liter of water absorbed, respectively) were not influenced by the rootstock.