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Rhuanito Soranz Ferrarezi and Donald S. Bailey

Aquaponics is a food production technology that combines aquaculture and hydroponics in an integrated recirculating system without soil ( Rakocy et al., 2006 ). The aquaponics ecosystem is composed by fish, bacteria, and plants ( Somerville et al

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Neo Edwin Nyakane, Moosa Mahmood Sedibe, and Elisha Markus

15 water pump with a flow rate of 900 L/h was used to fertigate experimental plants. The recirculating system had four dripper tubes allocated to four pots consisting of a single plant. The plants were irrigated twice a day for the first month, at

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Gary W. Stutte

NASA has investigated the use of recirculating nutrient film technique (NFT) systems to grow higher plants on long-duration space missions for many years and has demonstrated the feasibility of using recirculating systems on numerous crop species. A long duration (418-day) experiment was conducted at Kennedy Space Center, Fla., to evaluate the feasibility of using recirculating hydroponics for the continuous production of Solanum tuberosum L. `Norland'. The productivity of four sequential batch plantings was compared to staggered harvest and plantings. The accumulation of bioactive organic compounds in the nutrient solution resulted in reduced plant height, induced early tuber formation, and increased harvest index of the crops in both production systems. The changes in crop development were managed by increasing planting density and reducing cycle time to sustain production efficiency.

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Erin James and Marc van Iersel

The negative effects of nutrient runoff on the environment has come more to the forefront of greenhouse issues in the past few years. Alternative irrigation systems that reduce or eliminate runoff that are widely used in Europe have not yet gained much popularity in the southeastern United States, in part due to a lack of available information on their use. One such system is ebb-and-fl ow, which is a completely closed recirculating system, having no runoff whatsoever. In order to learn more about optimum growing practices using the ebb-and-fl ow system for bedding plants, marigolds and sunflowers were grown under a variety of conditions. After a 6-week period, pH of growing media of both marigolds and sunflowers decreased by 1, while EC increased by ≈1 dS/m. There were also significant differences in EC due to the different media types. The soilless medium with the highest percentage of vermiculite and lowest percentage of pine bark had the highest EC. Different types of fertilizer and fertilizer rates will be discussed, as well as interactions between fertilizer and media.

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J. Lopez, L.E. Parent, N. Tremblay, and A. Gosselin

In hydroponic recirculating systems, sulfate ions can accumulate to excessive levels and interfere with other nutrient ions. The objective of this research was to determine the effects of four sulfate concentrations on growth and mineral nutrition of greenhouse tomato plants (Lycopersicon esculentum Mill. cv. Trust). Tomato seeds were sown in flats and subsequently transplanted into rockwool slabs. Ten days after transplanting, plants were given four sulfate concentrations in nutrient solutions (S0 = 0.1, S1 = 5.2, S2 = 10.4, and S4 = 20.8 mM). The plots were arranged in a randomized complete-block design with four replications. Treatment S0 reduced dry weight of the top portion of the plant. A sulfate shortage in the nutrient solution decreased S concentrations in the leaf and decreased fruit number. Activities and concentrations of major ions in solutions expressed in mM or as row-centered logratios were correlated with corresponding foliar concentrations expressed in grams of nutrient per kilogram of dry matter or as row-centered logratios. Data were presented in this manner in order to explore interactive models describing relationships between mineral composition of both nutrient solutions and plant tissues. High concentrations of sulfate ions in the nutrient solution up to 20.8 mM did not affect tomato growth or yield. Tomato plants appeared prone to sulfate deficiency, but tolerant to sulfate concentrations up to 20.8 mM in the nutrient solution.

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Dawn M. Alleman and Thomas C. Weiler

Four experiments were conducted over 2 years focusing on water and fertilizer delivery methods with emphasis on minimal resource use. Poinsettia `Freedom', `Celebrate 2'. `Peppermint Pink', `Angelika White', `Lilo' and `Angelika Marble' and geranium `Kim', `Aurora', Ritz', and `Melody' cuttings were grown in 6 inch pots with peat-lite mix and were harvested at marketable size. Nitrogen efficiency was compared by replicating each irrigation treatment with soluble fertilizer (SF) and controlled release fertilizer (CRF). Crops grown with SF were started at 225ppm N for several weeks, then finished at 125ppm N after monitored EC had dropped below 1000μS. CRF treatments were potted up with 1.6 total grams of N available to the plant and irrigated throughout production with tap water. Irrigation treatments included: drip tube leaching, drip tube, ebb & flow, trough. trough lined with capillary mat, trough lined with plastic-covered capillary mat, flats of capillary mat, flats with plastic-covered capillary mat. Daily irrigation volumes were recorded. Weekly data collection included EC, pH, nitrate nitrogen. and ammonium nitrogen. Harvest data included plant dry weight, and total nutrient analyses of plants and substrate. Water efficiency was significantly improved in recirculating systems and with capillary mat systems. No significance was noticed in dry weight or final nutrient analyses across treatments. Significance existed in water quality throughout crop production.

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Richard V. Tyson, Danielle D. Treadwell, and Eric H. Simonne

, and manganese (Mn) ( Adler et al., 1996 ) and P, sulfur (S), K, and Fe ( Seawright et al., 1998 ) in recirculating water. Plants' uptake of NH 4 + and NO 3 − as well as other recirculating system nutrients like P reduces the waste stream in

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Yu-Wei Liu and Chen-Kang Huang

test) were measured. Each recirculating system had two replicates, and each replicate had 24 plants. The salts required to prepare 1 L of full-strength Yamazaki nutrient solution are listed in Table 1 . The series of experiments of growing butterhead

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Kellie J. Walters, Bridget K. Behe, Christopher J. Currey, and Roberto G. Lopez

applied as overhead irrigation (50%), daily single-event subirrigation (39%), constant subirrigation (29%), or other (18%) including drip, fog, hand (type not specified), and multiple-event-per-day subirrigation (data not shown). In recirculating systems

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Shannon M. Coleman, Bledar Bisha, Steven E. Newman, Marisa Bunning, and Lawrence D. Goodridge

spray paint to reduce the growth of algae. The NFT system consisted of recirculating system in which a waterfall pump (Flotec, Delavan, WI) located in the nutrient reservoir pumped nutrients through the hydroponic channel where the runoff was collected