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Gerry H. Neilsen, Denise Neilsen, Sung-hee Guak and Tom Forge

, contrasting with minimum fruit Ca concentration at low crop load. This implies that deficit irrigation strategies could result in inadequate fruit Ca concentrations if crop load is light. Fruit nutrient removal rates, as expressed in kilograms per hectare

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Leqi Yang, Xiao Yang, Hong Zhao, Danfeng Huang and Dongqin Tang

systems and is recognized as a high water productivity strategy. Ebb-and-flow system can adjust the water and fertilizer depending on the requirement of crop and reduce the overall water and nutrient use ( Ferrarezi et al., 2015b ). For instance, Holcomb

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Mohammed Z. Alam, Calvin Chong, Jennifer Llewellyn and Glen P. Lumis

nutrient concentrations; and 2) SDW and NO 3 -N concentrations in the leachate. Results Growth. In Expt. 1, growth of forsythia increased linearly with increasing rates of CRF under each of the three irrigation strategies (DrLoLF, HsLoLF

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Renee H. Harkins, Bernadine C. Strik and David R. Bryla

crops, including blackberry. The objective of the present study was to assess the impact of cultivar and weed management strategies on the accumulation and loss of plant biomass and nutrients during the first 3 years of establishment when using organic

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Sueyde F. de Oliveira, Paul R. Fisher, Jinsheng Huang and Simone da C. Mello

a complete solution to the problem of nutrient leaching; however, appropriate fertilizer application methods, CRF types, and irrigation strategies must be calibrated to match crop needs and the local environment ( Broschat and Moore, 2007 ). Both

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Elsa S. Sánchez, Ermita Hernández, Mark L. Gleason, Jean C. Batzer, Mark A. Williams, Timothy Coolong and Ricardo Bessin

strategies, and nutrient management treatments, are presented in Table 1 . Table 1. Details and dates of field experiments conducted in Pennsylvania, Iowa, and Kentucky during 2009–12 to evaluate timing or rowcover removal and nutrient management with

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Carolyn F. Scagel and Jungmin Lee

growing in different P rate and AMF inoculation treatments were compared after normalization using low P or non-AMF as the control treatment. A combination of significantly greater biomass, concentration, and content of a specific nutrient or phenolic was

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Aaron Heinrich, Richard Smith and Michael Cahn

rates are usually needed in first-cropped fields in spring because of low NO 3 concentrations following leaching in wet winters and also because of cool soil conditions that limit soil N mineralization from soil organic matter. Later in the growing

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D. Schwarz, H.-P. Kläring, K.T. Ingram and Y.-C. Hung

Diurnal changes in microclimate in a greenhouse are often greater than changes in daily averages over weeks or months. Thus, one may hypothesize that changing the nutrient solution concentration supplied to plants at intervals less than one day would improve tomato yield and quality. To test this hypothesis research was conducted to compare four nutrient control strategies for their effects on plant growth, fruit yield, fruit quality, and root characteristics of `Counter' tomato [Lycopersicon esculentum (L.) Mill.]. The four strategies were 1) ECvariable, adjustment of nutrient solution electrical conductivity (EC) at 15-min intervals according to greenhouse microclimate over the previous 15-min and empirical models of photosynthesis and transpiration; 2) ECdaily, daily adjustment of nutrient solution EC based on each morning's 24-hour weather forecast; 3) EC3.7, supply of a single high nutrient solution of 3.7 dS·m-1; or 4) EC1.5, low nutrient solution EC of 1.5 dS·m-1 for the entire growth period. Mean effluent EC levels were 1.8 dS·m-1 for treatment EC1.5, 5.1 dS·m-1 for treatment EC3.7, 3.6 dS·m-1 for treatment ECdaily, and 3.4 dS·m-1 for treatment ECvariable. Except for fresh weight (FW) of roots, growth characteristics did not differ significantly among treatments. Total production averaged 12.2 kg·m-2 FW and 1.0 kg·m-2 dry weight (DW); and fruit yield averaged 6.7 kg·m-2. Dry matter content, yield loss to blossom-end rot, and firmness responded linearly to treatment EC. In general, ECdaily yielded higher fruit quality and ECvariable lower fruit quality than that predicted by linear regression. Although our strategy of short-term dynamic changes of nutrient solution EC according to changes in climate variables did not increase yield, daily adjustment of nutrient solution EC improved external fruit quality characteristics and may be practical for grower adoption.

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Laurent Gauthier, Maher Trigui, André Boisvert and Mohamed Benmoussa

Transpiration is essential to the performance of tomato plants. In greenhouses, transpiration can be impeded by low vapor-pressure deficits (VPD). An experiment was conducted to measure the effect of VPD on transpiration rates for greenhouse tomatoes grown on a nutrient film. Four treatments were applied: high (0.8 kpa) day and night VPDs; high day and low night (0.4 kPa) VPDs; low day and low night VPDs; and variable VPDs. The VPD was controlled using fogging and ventilation. Hourly transpiration values were recorded. Results show a significant difference between treatments. The measured transpiration rates were compared to the values calculated with a transpiration model. A good fit between measured and calculated values was observed. The model is being used within a dynamic VPD control strategy.