Impact of the Hydroponic Cropping System on Growth, Yield, and Nutrition of a Greek Sweet Onion (Allium cepa L.) Landrace

Abstract

Nerokremmydo of Zakynthos, a Greek landrace of sweet onion producing a large bulb, was experimentally cultivated in a glasshouse using aeroponic, floating, nutrient film technique, and aggregate systems, i.e., AER, FL, NFT, and AG, respectively. The aim of the experiment was to compare the effects of these soilless culture systems (SCSs) on plant characteristics, including fresh and dry weight, bulb geometry, water use efficiency, tissue macronutrient concentrations, and uptake concentrations (UC), i.e., uptake ratios between macronutrients and water, during the main growth, bulbing, and maturation stages, i.e., 31, 62, and 95 days after transplanting. The plants grown in FL and AG yielded 7.87 and 7.57 kg m−2, respectively, followed by those grown in AER (6.22 kg m−2), while those grown in NFT produced the lowest yield (5.20 kg m−2). The volume of nutrient solution (NS) consumed per plant averaged 16.87 L, with NFT plants recording the least consumption. The SCS affected growth rate of new roots and “root mat” density that led to corresponding nutrient uptake differences. In NFT, reduced nutrient uptake was accompanied by reduced water consumption. The SCS and growth stage strongly affected tissue N, P, K, Ca, Mg, and S mineral concentrations and the respective UC. The UC of N and Κ followed a decreasing trend, while that of Mg decreased only until bulbing, and the UC of the remainder of the macronutrients increased slightly during the cropping period. The UC can be used as a sound basis to establish NS recommendations for cultivation of this sweet onion variety in closed SCSs.

Factors Affecting Production, Nutrient Translocation Mechanisms, and LED Emitted Light in Growth of Microgreen Plants in Soilless Culture

“…The harvesting period is 2–4 days for rice grass, 6–9 days for barley grass, 6–9 days for wheat grass, 6–9 days for oat grass, 8–12 days for jowar grass, 7 days for maize grass, 7–14 days for buckwheat, 4–6 days for mung bean, 6–8 days for chickpea, 12–14 days for mint, 20 days for basil, 18–20 days for sage, 16–22 days for oregano, 9–12 days for amaranth, 10–12 days for beet, 8–12 days for chard, 12–21 days for red swiss chard, 10–17 days for quinoa, 4–6 days for spinach, 14–25 days for chives, 12–14 days for garlic, 10–12 days for leeks, 12 days for onion, 15–25 days for carrot, 7–21 days for dill, 21–30 days for celery, 10–14 days for fennel, 5–10 days for radish, 5–20 days for aster cress, 8–16 days for mustard, 7–12 days for sunflower, 7–21 days for linseed, 7–21 days for cucumber, 4–20 days for Jute, 7–21 days for squash, 7–14 days for chicory, 8–16 days for endive, 7–16 days for lettuce, 7–21 days for beans, 7–28 days for welsh onion, 9–21 days for long green onion, 7–16 days for coriander, and 6–14 days for fenugreek ( Table ) .…”

Comparative analysis of data using machine learning algorithms: A hydroponics system use case

“…All such systems need special environmental monitoring, which nowadays is achieved by IoT systems [6]. Soilless culture is an alternative solution in restricted and environmentally degraded areas, including local varieties, such as Nerokremmydo of Zakynthos, a Greek big bulb sweet onion [7]. Evolution of Agriculture has led to the application of robots in tilling of the soils, raspberry pis have been used for the gathering of climatic data from the farm, automation of farm machinery, automation of animal processing, forecasting of the farm harvest, and monitoring of farm conditions.…”

Differential Metabolic Responses of Lettuce Grown in Soil, Substrate and Hydroponic Cultivation Systems under NH4+/NO3− Application

“…Nutrients are directly taken up by plants and stimulate the composition of different phytochemicals, such as ascorbic acid, phenolic compounds and flavonoids in plants [ 10 , 26 ]. The plant takes up nutrients through its roots with little effort and makes full use of its energy to grow tissues as compared to the soil system [ 27 , 28 ]. In contrast, plants growing in soil and substrate cultivation systems benefit from soil nutrient mineralization and microbial activity [ 29 ]…”