Effects of Protected Cultivation Environments on Aroma-Related Volatile Compounds in Cucumber: A Review

Cucumber (Cucumis sativus L.) is produced in diverse protected-cultivation systems, whose structures and management create distinct crop-zone environments. Its characteristic fresh aroma is associated mainly with volatile organic compounds (VOCs), particularly C6 and C9 aldehydes. We conducted a focused literature search in Web of Science, Scopus, PubMed, and CNKI using combinations of terms for cucumber, fruit VOCs, aroma or sensory quality, and protected cultivation or greenhouse systems. Primary studies measuring fruit VOCs or sensory attributes were distinguished from physiological, molecular, and non-volatile quality studies used to interpret potential mechanisms. This review synthesizes the LOX–HPL–HI pathway and evaluates how environmental factors and cultivation practices relate to cucumber fruit VOCs under protected production. In a protected-cultivation study, light intensity was positively associated with the daily accumulation of total VOCs and C6 aldehydes, whereas relative humidity was negatively associated with C9 aldehydes. Shading, supplemental lighting, and potassium supply also altered selected compounds under the conditions tested. A recent multi-population greenhouse–open-field comparison reported a higher relative share of alcohols and a lower relative share of C9 aldehydes in field-grown lines, while C6 aldehyde shares were similar between systems. These findings indicate compound-specific responses rather than a uniform effect of greenhouse cultivation. Protected cultivation is therefore best understood as a variable production context in which facility, microclimate, genotype, developmental stage, and management jointly shape the fruit volatile profile. Because chemical VOC measurements do not by themselves establish perceived aroma or overall flavor, sensory evidence is considered separately. By connecting facility-specific conditions with measured fruit VOC responses, this review provides a framework for interpreting and managing cucumber aroma-related traits across protected-cultivation systems.