tCucumber (Cucumis sativus L.) is an important vegetable crop belonging to the cucurbit family. Cucumbers are grown under protected cultivation worldwide. The influence of greenhouse covering materials on cucumber physiological processes and yield were evaluated. Three greenhouses, each with 48 m2,North–South direction and with wet-pad and fan cooling system were covered by either one of the 200 m thickness plastic films; newly developed NIR-reflective film (C1) and two commercial films (C2and C3). The predicted equations of the photosynthetic rate (mol CO2m−2s−1), transpiration (m molH2O m−2s−1), intercellular CO2concentration (mol CO2mol−1), stomatal conductance (mol H2O m−2s−1) and leaf temperature were obtained by multiple regression analysis of the measured data. The aver-age temperatures were 22.27 ± 2.06◦C, 23.80 ± 2.26◦C, 25.42 ± 2.41◦C and 31.12 ± 4.30◦C for films C1, C2,C3 and outside respectively. The results revealed that vapour pressure deficit (VPD) under (C1) was lowerthan that under C2and C3during the production period. The average of photosynthetic rate values were16.61 ± 5.49, 15.51 ± 5.18 and 14.91 ± 4.78 mol CO2m−2s−1for films C1, C2and C3, respectively. While,the transpiration rate and the intercellular CO2concentration under (C1) were higher than those underC2and C3during the production period. Therefore, fruit and yield traits increased under C1followed by C2and then by C3of greenhouses covers. It can be concluded that the greenhouses plastic covering materialhas a great influence on the internal environmental conditions, physiological processes and productivityof cucumber plants.