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Article

Enhancing Soilless Production of Portulaca oleracea, Mesembryanthemum crystallinum and Valerianella locusta Through Nitrogen Form Ratio Optimization and Biostimulant Application

1
Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece
2
Laboratory of Cell Technology, Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece
3
Department of Agricultural, Food and Forest Sciences, University of Palermo, 90128 Palermo, Italy
4
Agricultural Research Institute, Department of Natural Resources and Environment, P.O. Box 22016, 1516 Nicosia, Cyprus
*
Author to whom correspondence should be addressed.
Horticulturae 2025, 11(9), 1076; https://doi.org/10.3390/horticulturae11091076
Submission received: 19 August 2025 / Revised: 2 September 2025 / Accepted: 4 September 2025 / Published: 5 September 2025

Abstract

Underutilized leafy greens are considered as functional plant species primarily due to their resilience to abiotic stress factors, low nutrient requirements, and high nutritional value. Over the past 30 years, many experiments have been conducted to identify nutrient-efficient species, cultivars, landraces, and ecotypes, but few have successfully entered mainstream agriculture. The integration of these species into advanced horticultural systems, such as hydroponics, has the potential to further strengthen their impact on sustainable agriculture by minimizing use of resources, enabling year-round cultivation, and improving the nutritional profile of the harvested produce. As leafy vegetables, a primary food safety concern is the accumulation of nitrates in the leaves. In hydroponics, this issue is usually addressed by balancing the NH4-N/total-N ratio (Nr) in the nutrient solution. Provided that the plant responses to high ammonia supply are species-dependent, three wild leafy greens, iceplant, corn salad, and common purslane, were grown in a soilless culture, with perlite as the substrate, under low (0.04) and high (0.12) Nr on a molar basis. Additionally, the potential of protein hydrolysates (PH) and seaweed extracts (SW) to alleviate plant tolerance to excess ammonia supply was also investigated. In terms of yield, high Nr led to significant yield restrictions in iceplant that reached 28%, while on corn salad, it had a positive impact, with yield increasing by 18%. Both biostimulant applications enhanced iceplant productivity only under optimal Nr conditions (0.04). Apart from yield responses, biofertilizers had no substantial impact on the plant nutrient profile. In contrast, high Nr suppressed nitrate accumulation in fresh leaves, while enhancing micronutrient uptake in all three plant species. In conclusion, this study highlights the pivotal role of biostimulants as plant stress protectors and growth regulators and identifies the optimal Nr ratio for maximizing the yield and quality performance of corn salad, iceplant, and common purslane in soilless cultivation systems.
Keywords: plant nutrition; hydroponics; purslane; iceplant; corn salad; seaweed extracts; protein hydrolysates; nitrates plant nutrition; hydroponics; purslane; iceplant; corn salad; seaweed extracts; protein hydrolysates; nitrates

Share and Cite

MDPI and ACS Style

Ntanasi, T.; Karavidas, I.; Giannothanasis, E.; Spyrou, G.P.; Karaviti, T.; Marka, S.; Napoli, S.; Neocleous, D.; Ntatsi, G. Enhancing Soilless Production of Portulaca oleracea, Mesembryanthemum crystallinum and Valerianella locusta Through Nitrogen Form Ratio Optimization and Biostimulant Application. Horticulturae 2025, 11, 1076. https://doi.org/10.3390/horticulturae11091076

AMA Style

Ntanasi T, Karavidas I, Giannothanasis E, Spyrou GP, Karaviti T, Marka S, Napoli S, Neocleous D, Ntatsi G. Enhancing Soilless Production of Portulaca oleracea, Mesembryanthemum crystallinum and Valerianella locusta Through Nitrogen Form Ratio Optimization and Biostimulant Application. Horticulturae. 2025; 11(9):1076. https://doi.org/10.3390/horticulturae11091076

Chicago/Turabian Style

Ntanasi, Theodora, Ioannis Karavidas, Evangelos Giannothanasis, George P. Spyrou, Theoni Karaviti, Sofia Marka, Simona Napoli, Damianos Neocleous, and Georgia Ntatsi. 2025. "Enhancing Soilless Production of Portulaca oleracea, Mesembryanthemum crystallinum and Valerianella locusta Through Nitrogen Form Ratio Optimization and Biostimulant Application" Horticulturae 11, no. 9: 1076. https://doi.org/10.3390/horticulturae11091076

APA Style

Ntanasi, T., Karavidas, I., Giannothanasis, E., Spyrou, G. P., Karaviti, T., Marka, S., Napoli, S., Neocleous, D., & Ntatsi, G. (2025). Enhancing Soilless Production of Portulaca oleracea, Mesembryanthemum crystallinum and Valerianella locusta Through Nitrogen Form Ratio Optimization and Biostimulant Application. Horticulturae, 11(9), 1076. https://doi.org/10.3390/horticulturae11091076

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