Evaluation of alternative substrates under varying fertigation methods for highwire cucumber propagation

Authors: HAMAL, MANISHA - The Ohio State University; ESPINOZA-AYALA, ALEXANDRA - The Ohio State University; TAYLOR, LESLIE - The Ohio State University; Altland, James; SAMARAKOON, UTTARA - University Of Florida

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2026
Publication Date: 2/26/2026
Citation: Hamal, M., Espinoza-Ayala, A., Taylor, L., Altland, J.E., Samarakoon, U. 2026. Evaluation of alternative substrates under varying fertigation methods for highwire cucumber propagation. HortScience. 61(4):675–684. https://doi.org/10.21273/HORTSCI19123-25.
DOI: https://doi.org/10.21273/HORTSCI19123-25

Interpretive Summary: Substrates used for cucumber production, including rockwool and peat, are widely used but have high carbon footprints and sustainability issues. The objective of this research was to identify sustainable and effective substrates for cucumber propagation in highwire hydroponic systems. We evaluated alternative organic substrates, specifically a wood fiber and coir mix (WF coir) and fine grade pine bark (PB fine), under different fertigation methods and nutrient concentrations. The performance of these substrates was compared to that of rockwool and peat across three greenhouse experiments. It was found that WF coir consistently supported equal or superior cucumber germination, seedling growth, biomass accumulation, and root development compared to rockwool, while PB fine showed variable results. WF coir demonstrated potential as a sustainable replacement for rockwool and peat, particularly under high-nutrient, overhead irrigation conditions. This finding suggests that cucumber growers can adopt WF coir as a renewable and locally available substrate, reducing the environmental impact of their production systems while maintaining or even improving crop performance

Technical Abstract: Choosing the right substrate plays a critical role in propagation success. An ideal substrate should support high germination and vigorous root and shoot development, while being sustainably sourced and locally available. Organic substrates such as pine bark, wood fiber, and coir are being explored as alternatives to conventional substrates like mineral wool, perlite, and peat, in highwire vegetable production. However, their performance during propagation under different fertigation strategies remains unclear. This study evaluated the interaction of three organic substrates—wood fiber and coir mix (WF coir), fine grade pine bark (PB fine), and peat—along with two electrical conductivity (EC) levels (1.1 and 2.2 mS·cm'¹) and three irrigation methods for cucumber propagation across three sequential greenhouse experiments. In experiment 1, WF coir, and PB fine were compared to rockwool under overhead irrigation with supplemental subirrigation. Experiment 2 tested the impact of concentration of nutrient solution (EC levels). Experiment 3 evaluated substrates under overhead irrigation only. WF coir performed comparably to rockwool in most growth parameters but exceeded it in shoot fresh weight and leaf area (Experiment 1). PB fine supported greater seedling height than peat, while peat showed the highest SPAD value among all substrates (Experiment 2). In Experiment 3, WF coir, PB fine, and rockwool produced taller seedlings under higher EC, while peat maintained consistent height across EC levels. Overall, WF coir demonstrated potential as a sustainable replacement for rockwool and peat under high-nutrient, overhead irrigation conditions. PB fine may require amendments to enhance water and nutrient retention.