There is a general belief that the quality of tomatoes ripened on vine is better than tomatoes ripened off the vine, influencing among other parameters, the price of this commodity. We compared the quality of hydroponic tomatoes ripened on and off vine by chemical, physical, and sensory evaluation to find what attributes are affected and to what extent. Lycopene, ␤-carotene, total and soluble solids, moisture content, ascorbic acid, acidity, pH, texture, and color were analyzed. Tomatoes ripened on vine had significantly more lycopene, ␤-carotene, soluble and total solids, higher a* and lower L*, and were firmer. However, a 100-judge panel rated only the color and overall liking of the vine-ripened tomatoes as more intense than the fruit ripened off vine. Therefore, the chemical and physical differences were mostly not large enough to influence the panelist's perception. The characterization of tomatoes ripened on and off vine may help to guide post-harvest handling and treatment and to improve the quality of tomatoes ripened off vine.

Limited-cluster production systems may be a useful strategy to increase crop production and profitability for the greenhouse tomato (Lycopersicon esculentum Mill). In this study, using an ebb-and-flood hydroponics system, we modified plant architecture and spacing and determined the effects on fruit yield and harvest index at two light levels. Single-cluster plants pruned to allow two leaves above the cluster had 25% higher fruit yields than did plants pruned directly above the cluster; this was due to an increase in fruit weight, not fruit number. Both fruit yield and harvest index were greater for all single-cluster plants at the higher light level because of increases in both fruit weight and fruit number. Fruit yield for two-cluster plants was 30% to 40% higher than for singlecluster plants, and there was little difference in the dates or length of the harvest period. Fruit yield for three-cluster plants was not significantly different from that of two-cluster plants; moreover, the harvest period was delayed by 5 days. Plant density (5.5, 7.4, 9.2 plants/m2) affected fruit yield/plant, but not fruit yield/unit area. Given the higher costs for materials and labor associated with higher plant densities, a two-cluster crop at 5.5 plants/m2 with two leaves above the cluster was the best of the production system strategies tested.

A qualitative systems approach to controlled environment agriculture (CEA) is presented by means of several multi-institutional projects integrated into a demonstration greenhouse at the Burlington County Resource Recovery Complex (BCRRC), N.J. The greenhouse has about 0.4 ha of production space, and is located about 800 m from the about 40-ha BCRRC landfill site. A portion of the landfill gas produced from the BCRRC site is used for microturbine electricity generation and for heating the greenhouse. The waste heat from the turbines, which are roughly 15 m from the greenhouse, is used as the main heat source for the greenhouse in the winter months, and to desalinate water when heating is not required. Recovery of this waste heat increases the energy efficiency of the four 30-kW turbines from about 25% to 75%. Within the greenhouse, aquaculture and hydroponic crop production are coupled by recycling the aquaculture effluent as a nutrient source for the plants. Both the sludge resulting from the filtered effluent and the inedible biomass from harvested plants are vermicomposted (i.e., rather than being sent to the landfill), resulting in marketable products such as soil amendments and liquid plant fertilizer. If suitably cleaned of contaminants, the CO2 from the landfill gas may be used to enrich the plant growing area within the greenhouse to increase the yield of the edible products. Landfill gas from the BCRRC site has successfully been processed to recover liquid commercial grade CO2 and contaminant-free methane-CO2, with the potential for this gas mixture to be applied as a feedstock for fuel cells or for methanol production. Carbon dioxide from the turbine exhaust may also be recovered for greenhouse enrichment. Alternatively, algal culture may be used to assimilate CO2 from the turbine exhaust into biomass, which may then be used as a biofuel, or possibly as fish feed, thus making the system more self-contained. By recycling energy and materials, the system described would displace fossil fuel use, mitigating negative environmental impacts such as greenhouse gas emissions, and generate less waste in need of disposal. Successful implementation of the coupled landfill (gas-to-energy · aquaponic · desalination) system would particularly benefit developing regions, such as those of the Greater Caribbean Basin.

Hydroponic sweet basil (O. basilicum L.) farming uses a recirculating nutrient solution that may spread waterborne microbial contamination including algae. Plasma, the fourth state of matter, generates antimicrobial reactive oxygen and nitrogen species when exposed to water. The objective of this work was to study the effect of plasma-treated water-based nutrient solution on plant growth and in reduction of algae. Basil plants were grown in isolated ebb and flow hydroponic systems (under monitored environmental conditions) using nutrient solution (NS) and plasma-activated nutrient solution (PANS) with two separate treatments: the same irrigation solutions were used in the growth cycle (Treatment 1: NST1 and PANST1 once at the beginning growth cycle) and new irrigation solutions at every week of the growth cycle (Treatment 2: NST2 and PANST2). The plant growth parameters (height, fresh and dry weight, number of branches and nodes, root length, leaf index), quality parameters (color, texture, aroma, and tissue nutrients concentration), and algae concentrations were measured. Compared to NST1, plants grown on PANST1 were significantly taller (up to 12%), had a higher fresh mass (up to 29%) and dry mass (up to 45%), and had a higher greenness value (up to 28%). Algae growth was significantly reduced in the PANST2 reservoir (up to 24%) compared to the NST2 reservoir. It was confirmed that Treatment 1 significantly improved the yield, morphology, and quality of sweet basil plants, while Treatment 2 was best suited to decreasing algae concentration in the hydroponic environment. This preliminary study indicated that PANS could improve the quality and growth of sweet basil in hydroponic farming while controlling the algae growth in the growing environment.

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