Hydroponic technologies

This open access book, written by world experts in aquaponics and related technologies, provides the authoritative and comprehensive overview of the key aquaculture and hydroponic and other integrated systems, socio-economic and environmental aspects. Aquaponic systems, which combine aquaculture and vegetable food production offer alternative technology solutions for a world that is increasingly under stress through population growth, urbanisation, water shortages, land and soil degradation, environmental pollution, world hunger and climate change.Hydroponics is a method to grow crops without soil, and as such, these systems are added to aquaculture components to create aquaponics systems. Thus, together with the recirculating aquaculture system (RAS), hydroponic production forms a key part of the aqua-agricultural system of aquaponics. Many different existing hydroponic technologies can be applied when designing aquaponics systems. This depends on the environmental and financial circumstances, the type of crop that is cultivated and the available space. This chapter provides an overview of different hydroponic types, including substrates, nutrients and nutrient solutions, and disinfection methods of the recirculating nutrient solutions

Effect of electrical conductivity, fruit pruning, and truss position on quality in greenhouse tomato fruit

The combined effects of electrical conductivity (an EC of 2.5 dS m-1 or 8 dS m-1 in the root zone) and fruit pruning (three or six fruit per truss) on tomato fruit quality were studied in a greenhouse experiment, planted in January 2005. Taste-related attributes [dry matter content (DM), total soluble solids content (SSC), titratable acidity (TA), glucose, fructose and citric acid content] and health-promoting attributes (lycopene, ß-carotene, vitamin C, and total antioxidant activity) of tomato fruits harvested on the vine from the fifth or tenth truss positions were determined. The quality of tomato fruits was improved by high EC. A high EC in the root zone increased the DM content, total SSC, TA, as well as glucose, fructose and citric acid contents. A significantly higher lycopene and ß-carotene content was also observed [on a fresh weight (FW) and dry weight (DW) basis] with a high EC in the root zone. The accumulation of different compounds that determine tomato fruit quality differed between the fifth and tenth truss. In particular, the lycopene content was reduced, whereas the ß-carotene content was increased in the tenth truss with respect to the fifth truss, most likely because of higher temperatures during ripening of the tenth truss. Fruit pruning increased fruit FW by 42% and positively influenced the DM content and total anti-oxidant activity, while a negative effect was observed on lycopene and citric acid contents (on a FW and DW basis). EC and fruit pruning both had a strong effect on fruit size; however, EC had a much stronger impact on taste and health-related fruit quality attributes. A small interaction between EC and fruit pruning was found for marketable yield, fructose and glucose content, fruit firmness, and P and Ca concentrations in fruits

The influence of K:Ca:Mg:Na Ratio and total concentration on yield and fruit quality of soilless-grown tomatoes: A modelling approach

This study describes an application of Systematic Variation method (SV) for optimizing cation proportions (K, Ca, Mg, Na) and the total element concentration of hydroponically-grown tomatoes. A randomized complete-block design with 5 replications (3 plants per experimental unit) was used to compare a factorial combination of 4 proportions of K:Ca:Mg:Na and 2 total concentrations of elements (30 and 60 meq L-1). Each of the cation proportion treatment was defined by a high proportion of one cation (V=0.64) and an equally low proportion of the others (v=0.12) for a total amount of one (V + 3v = 1). The highest total and marketable yield were obtained in treatment with high proportion of K (avg. 2.94 and 2.72 kg plant-1, respectively) and Ca (avg. 2.84 and 2.65 kg plant-1, respectively), while treatments with high proportion of Mg (avg. 2.59 and 2.22 kg plant-1, respectively) and Na (avg. 2.21 and 2.09 kg plant-1, respectively) gave the lowest values. The highest incidence of blossomend rot was observed in treatments with high proportion of Mg and K (avg. 10.8 % and 3.7 % of total yield, respectively). Fruit quality (soluble solids, titratable acidity, EC) improved by increasing the proportion of K and Na and the total concentration. The SV method showed that for maximise the marketable yield it is necessary to include a large amount of K and Ca in the nutrient solution