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Junyang Song

increasing trend. The variation of bulb weight was more significant than the bulb volume. The bulb weight could better reflect the dynamics of bulb nutrients than the bulb volume. During the dynamic growth and development of lilies, the change of bulb weight

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Junxin Huang, Robert Heyduck, Richard D. Richins, Dawn VanLeeuwen, Mary A. O’Connell, and Shengrui Yao

cultivar trials have been set up at four NMSU agricultural science centers in New Mexico. The objective of this study was to assess the nutrient dynamics during jujube fruit maturation and the differences among cultivars for nutrient characteristics

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Julie M. Tarara, Paul E. Blom, Bahman Shafii, William J. Price, and Mercy A. Olmstead

., 1993 ; Reynolds et al., 2005 ) and previously we investigated its seasonal dynamics in grapevine ( Blom and Tarara, 2007 ). Another commonly measured static variable, the mass of dormant cane prunings (e.g., Bennett et al., 2005 ; Naor et al., 2002

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Ellen T. Paparozzi, Jazbaat K. Chahal, Petre Dobrev, Elizabeth A. Claassen, Walter W. Stroup, and Radomira Vankova

., 2009 ; Kiba et al., 2011 ). As cytokinins, often referred to as the leaf regreening hormone, also exhibit positive effects on chlorophyll concentration in leaves we decided to compare the dynamics of the response to N deficiency and subsequent N

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Richard Smith, Michael Cahn, Timothy Hartz, Patricia Love, and Barry Farrara

California conditions, and on current irrigation practices. Improved cole crop N management requires a more complete understanding of soil and crop N dynamics of these crops within the intensive crop production scheme of this region. This study was undertaken

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Mathieu Ngouajio and Milton E. McGiffen Jr.

Organic agriculture is growing in importance worldwide. In the United States, the rate of increase of organic growers was estimated at 12% in 2000. However, many producers are reluctant to undertake the organic transition because of uncertainty of how organic production will affect weed population dynamics and management. The organic transition has a profound impact on the agroecosystem. Changes in soil physical and chemical properties during the transition often impact indirectly insect, disease, and weed dynamics. Greater weed species richness is usually found in organic farms but total weed density and biomass are often smaller under the organic system compared with the conventional system. The improved weed suppression of organic agriculture is probably the result of combined effects of several factors including weed seed predation by soil microorganisms, seedling predation by phytophagus insects, and the physical and allelopathic effects of cover crops.

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Amaya Atucha, Ian A. Merwin, Chandra K. Purohit, and Michael G. Brown

dynamics in a year with N and P fertilizer additions (2005) and another year without ground-applied fertilizers (2007). Trees were fertilized in May 2005 applying ammonium nitrate (34N–0P–0K) at a rate of 318 g/tree equivalent to 0.108 kg N/tree and 60 kg N

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Angela Y.Y. Kong, Cynthia Rosenzweig, and Joshua Arky

synchronized with crop demand to optimize crop yield. A better understanding of N dynamics and cycling in rooftop farm substrate would elucidate how to best manage rooftop farm systems for optimal productivity and environmental benefits, while minimizing N

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Xiaofeng Yang, Gang Li, Weihong Luo, Lili Chen, Shaopeng Li, Ming Cao, and Xuebin Zhang

nitrogen management, a model is needed for quantitatively assessing the impacts of nitrogen on growth dynamics and yield. The objective of this study was to develop a dynamics model to quantitatively investigate the impacts of nitrogen on growth dynamics

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J.M.S. Scholberg, L.R. Parsons, and T.A. Wheaton

Improving our understanding of processes that control and limit nitrogen uptake by citrus can provide a scientific basis for enhancing nitrogen fertilizer use efficiency. Nitrogen uptake dynamics of two rootstock seedlings will be compared to those of young budded trees. Three-month old Swingle citrumelo [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] and Volkamer lemon (C. volkameriana Ten. & Pasq.) trees were planted in PVC columns filled with a Candler fine sand. Field experiments were conducted using 4-year-old `Hamlin' orange trees [Citrus sinensis (L.) Osb.] grafted on `Carrizo' [C. sinensis × Poncirus trifoliata (L.) Raf.] or on Swingle citrumelo. Trees were either grown in solution culture using 120-L PVC containers or in 900-L PVC tubs filled with a Candler fine sand. Additional trees were planted in the field during Spring 1998. Two lateral roots per tree were trained to grow in slanted, partly burried, 20-L PVC columns filled with a Candler fine sand. Nitrogen uptake from the soil was determined by comparing the residual N extracted by intensive leaching from planted units with that of non-planted (reference) units. With the application of dilute N solutions (7 mg N/L), plants reduced N concentrations to near-zero N concentrations within days. Applying N at higher concentrations (70 or 210 mg N/L) resulted in higher initial uptake rates, increased residual soil N levels, and reduced nitrogen uptake efficiency. Contributions of passive uptake to total nitrogen uptake ranged from less than 5% at soil solution concentrations around 3 ppm N to 20% to 30% at concentrations of 60 ppm N.