Optimised fertigation improves yield and quality of cucumbers for resource efficiency and economic return in high-tech greenhouses

Fertigation systems in high-tech greenhouses improve crop performance by optimising water and nutrient use, which is critical for sustainable food production. Electrical conductivity (EC), an indicator of nutrient content in fertigation solutions, reflects the electrolyte concentrations and significantly influences plant growth and resource use efficiency. This study evaluated the productivity and quality of two cucumber varieties, Lebanese and Continental, grown under three EC levels (1.0, 2.5, and 3.5 dS/m) in high-tech greenhouses. The EC 2.5 fertigation led to the highest cucumber yields, enhanced water use efficiency (WUE) and fruit quality. Key physiological responses, such as net photosynthesis, stomatal conductance, and transpiration rates, remained stable across EC levels, while electron transport rates were highest at EC 2.5. Highlighting the potential benefits of maintained fertigation in glasshouse the study revealed that EC 2.5 performed better in maintaining the shelf life of fruits at 2 °C and 7 °C. The study also showed significant differential expression of potassium transporter genes, which correlated with yield and WUE, highlighting the molecular link between fertigation management and plant responses. A comprehensive cost-benefit analysis of the three fertigation levels in Qatar and Australia revealed that the greenhouse cucumber business in Australia can break even in 3–5 years. The highest net present value was recorded in EC 2.5, with Australia achieving 31.3 USD m^−2·year⁻¹ and Qatar 13.1 USD m^−2·year⁻¹. These findings suggest that optimised fertigation levels could enhance resource sustainability, crop performance, and economic viability in greenhouse cucumber production, particularly in water-scarce and extreme climate regions.