How to Efficiently Produce the Selenium-Enriched Cucumber Fruit with High Yield and Qualities via Hydroponic Cultivation? The Balance between Selenium Supply and CO2 Fertilization

Summary

This hydroponic experiment demonstrated that low-level selenium supply (0.125 mg Se L⁻¹) optimises the production of selenium-biofortified cucumber whilst maintaining both yield and mineral nutrient quality under elevated CO2 fertilisation. The treatment enhanced photosynthetic rate and transpiration, resulting in cucumber fruit with 0.63 mg kg⁻¹ selenium — sufficient to meet adult dietary requirements in an 87 g serving — whilst preserving concentrations of essential minerals including nitrogen, phosphorus, potassium, calcium and manganese. The findings suggest a specific balance between selenium supply and CO2 fertilisation can overcome the typical nutrient dilution effect associated with elevated CO2 in greenhouse production.

Regional applicability

The findings are applicable to United Kingdom protected horticulture (greenhouse production), which increasingly uses CO2 enrichment and hydroponic systems. Selenium biofortification via hydroponic selenite supply is a control-environment technique with high transferability; however, UK cucumber production differs regionally in deployment of CO2 enrichment, and the optimal selenite dosage would require validation under UK seasonal light and temperature conditions.

Key measures

Net photosynthesis rate, transpiration rate, photosynthetic pigments, dry weight, fruit yield, soluble sugar concentration, selenium concentration in fruit, mineral nutrient concentrations (N, P, K, Ca, Mn, S, Mg, Fe, Zn), soluble protein content, selenium accumulation and use efficiency

Outcomes reported

The study measured effects of CO2 concentration and selenium supply on cucumber growth, photosynthesis, fruit yield, selenium accumulation, and mineral nutrient composition. Optimal selenium supply (0.125 mg Se L⁻¹) under elevated CO2 produced selenium-enriched fruit with maintained mineral nutrient concentrations and sufficient selenium content to meet adult dietary requirements in 87 g serving.

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