Modified hydroponics and phenolic foam as technological innovations in the production of coffee seedlings from cuttings

Brazilian coffee production represents an important activity in the country’s agricultural sector and, for this reason, it requires innovative technologies for the production of seedlings, which is one of the most important inputs in crop implantation. Thus, plant cloning by cutting, mineral nutrition via modified hydroponics and the use of alternative substrates appear as technological innovations for seedling production. This study evaluated the production of clonal coffee seedlings in a modified hydroponic system in comparison to the conventional climate-controlled greenhouse system, using vermiculite and phenolic foam as alternative substrates. At the end of the experiment, the seedlings were analyzed for growth (height, stem diameter, number of total leaves, leaf area, root area, shoot and root dry matter) and physiological (chlorophyll content and stomatal conductance) characteristics. For the statistical analysis, a completely randomized design was used in a factorial scheme 2 (types of substrate) x 2 (cultivation systems) with six replications and ten plants per plot. The innovative modified hydroponic system leads to a greater growth of coffee seedlings produced by cuttings in tubes with vermiculite compared to those produced in conventional systems. The substrate phenolic foam can be used alternatively in the air-conditioned greenhouse system. However, in the modified hydroponic system, it is not indicated, as it causes total seedling mortality.

Removal of Pathogens from Domestic Wastewater Using Small-Scale Gradual Hydroponics Planted with Duranta erecta, Addis Ababa, Ethiopia

This study aimed to evaluate the treatment potential of gradual hydroponics planted with Duranta erecta in the removal of pathogens from domestic wastewater. Two experimental and control units were configured in series. Each unit contains three bioreactors and was arranged in a cascaded configuration. The two experimental units used both plant and media, but the two control units used only media to treat the wastewater. Gravel and polyester sponge were used as media. Experimental unit 1 and control unit 1 used gravel as media; however, experimental unit 2 and control unit 2 used polyester sponges as media. The experiment was operated at hydraulic retention times of 1, 3, 5, and 7 days in a continuous mode. The performance of the hydroponic system was evaluated by characterizing the influent and effluent quality using standard methods. At optimum hydraulic retention time (7 days), the average removal of experimental units 1 and 2 was 98.7% and 89.8% for heterotrophic bacteria, 96.2% and 86.8% for total coliform, and 92.9% and 84.0% for fecal coliform, respectively. Analysis of variance showed that there was a significant difference P < 0.05 between the two experimental and control units in removing pathogens, but no significant difference P > 0.05 was observed between the two experimental units and between the two control units. Heterotrophic bacteria and coliforms were satisfactorily removed from domestic wastewater via a gradual hydroponic system. Hence, the hydroponic treatment system planted with Duranta erecta has a promising potential in the removal of pathogens from domestic wastewater in developing countries including Ethiopia.

The Effectiveness of Automated Sonic Bloom Method in An IoT-Based Hydroponic System

One of the solutions for food security is planting using hydroponic method and to increase productivity and help hydroponic grow faster and facilitate in monitoring hydroponic growth, sonic bloom and Internet of Things (IoT) are two technologies that can be used. However, in previous studies, the two systems have not been interconnected. The aim of this study is to evaluate the effectiveness of the combination of the two systems mentioned, hence creating an automated sonic bloom method in an IoT-based hydroponic system. To test the proposed method, this system is implemented with bok choi as the hydroponic plant using the DFT technique. The automated sonic bloom is embedded to the IoT system with DF Player Mini module, RTC module, and speakers. The evaluation is done by comparing growth parameters and the crop parameters. The results show that the system with sonic bloom produces fresh weight of 0,44-0,56 g and dry weight of 0,21–0,33 g. The mentioned results are superior to the system without sonic bloom, where fresh weight is 0,17–0,25 g and dry weight is 0,08–0,13 g. It can be concluded that the IoT-based sonic bloom system is effective in increasing the growth rate and hydroponic production rate.

Ionic homeostasis, biochemical components and yield of Italian zucchini under nitrogen forms and salt stress

This research was carried out aiming at evaluating the effects of nitrate and ammonium ions on nutrient accumulation, biochemical components and yield of Italian zucchini (cv. Caserta) grown in a hydroponic system under salt stress conditions. The experiment was carried out in a greenhouse utilizing an experimental design in randomized blocks, arranged in a 2 x 5 factorial scheme, with 4 replications. The treatments consisted of two forms of nitrogen (nitrate - NO3- and ammonium - NH4+) and 5 electrical conductivity levels of irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1). The analysis of the results indicated that supply of N exclusively in NH4+ form promotes greater damage to the leaf membrane and reduction in accumulation of macronutrients and higher Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in the shoots of zucchini plants. Electrical conductivity of irrigation water above 2.0 dS m-1 reduces the accumulation of nutrients in shoot and yield of Italian zucchini plant. The toxicity of NH4+ under Italian zucchini plants overlap the toxicity of the salinity, since its fertilization exclusively with this form of nitrogen inhibits its production, being the NO3- form the most suitable for the cultivation of the species.

Fuzzy Logic Controller for Automating Electrical Conductivity and pH in Hydroponic Cultivation

This study proposes a fuzzy logic controller for adjusting the electrical conductivity (EC) and pH of the nutrient solution in a hydroponic system. The proposed control system detects the EC and pH of the solution through sensors and adjusts the working time of the solution pump through the fuzzy controller. Specifically, the EC and pH of the nutrient solution are maintained at specific values. A Raspberry Pi3 development board is used in the proposed control system to realize and solve the problem of adjusting the EC and pH of the solution. In the fuzzy controller, the inputs are EC and pH sensors, and the output is the operating time of the pump. Experimental results indicate that the proposed control system can effectively reduce the measurement burden and complex calculations of producers by adjusting nutrient solutions.

Agronomic and sensory evaluation of lettuce in hydroponic system

Lettuce is the most important leafy vegetable in Brazil. Hydroponic lettuce cultivation has grown due to the viability of harvesting throughout the year. In this context, this study aimed to evaluate the agronomic characteristics, color, and preference of curly lettuce in the NFT hydroponic system. Six lineages (6601-1A, 6601-2L, 7016-6A, 7119-1B, 7223-1A, and 7224-4A) and two commercial cultivars (Brida and Vanda) of lettuce were used, in a completely randomized blocks design with four replications. Shoot length, root length, stem length, number of leaves, stem diameter, plant diameter, shoot fresh mass, root fresh mass, chlorophyll content, instrumental color, and sensory characteristics were evaluated. As for agronomic evaluation, the bolting of 6601-2L lettuce was relevant in different attributes. The Vanda lettuce and the lineage 7016-6A presented best performances for shoot fresh mass (399.44 and 378.63 g, respectively), while the lineages 7119-1B and 6601-2L present the worst performance (279.50 and 273.13 g, respectively). There was variation in chlorophyll content and luminosity, however, the evaluators did not notice differences between lettuces for brightness or green color, as well as for crunchy texture. Lettuces 6601-2L, 7224-4A, 6601-1A, Brida, 7223-1A, and 7119-1B were preferred. The variation among plants may be due to different situations, such as harvesting times and bolting, and a direct relationship between agronomic properties and preference among lettuces has not been established yet.

Quality and Yield of Lettuce in an Open-Air Rooftop Hydroponic System

In this study, the yield and growth performance of lettuce in an open-air rooftop hydroponic system were investigated. Lettuce was grown in a closed recirculating nutrient film technique (NFT) unit using a standard nutrient solution (NS). Yield, fresh weight, and nutrient content in the leaf tissue of the harvested lettuce were measured. The results were compared with the results obtained in indoor hydroponic lettuce growth with artificial lightning. Despite strong winds during the growth period, 25% of the total lettuce heads weighed twice the marketable weight; however, 25% of the total lettuce heads were below the marketable weight. A more efficient nutrient uptake was indicated by the lettuces in the rooftop system compared with the uptake in the indoor system. Foliar analysis revealed a higher content of all nutrients in the leaves of rooftop hydroponic lettuce compared with indoor hydroponic lettuce. This study suggests that hydroponic rooftop-grown lettuce can be competitive with their indoor counterparts if the rooftop hydroponic system is protected from extreme weather conditions.

Opportunities and constraints in hydroponic crop production systems: A review

Hydroponic crops can be grown using a variety of media and production systems (NFT system, wick system, drip system, ebb flow system etc.). EC and pH management are required to successfully handle these hydroponic systems (water quality and nutrient solution maintenance). These hydroponics systems have gained rapid adoption due to disciplined management of their resources and food production. Although the hydroponic system was developed in a closed-loop system, and substrate nutrition increases production, it is not cost-effective to develop this system on big scale. It is critical to design a low-cost hydroponic structure that decreases reliance on human labour and lowers overall startup cost in order to increase the commercialization of hydroponic farms. We need more research to develop more productive and cost-effective organic nutrient solutions and improve hydroponic crop production systems. In this review paper, we will discuss the opportunity and challenges in hydroponic crop production systems.