The effects of plastic greenhouse covering on cucumber (Cucumis sativus L.) growth

Cucumber (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 μm thickness plastic films; newly developed NIR-reflective film (C1) and two commercial films (C2 and C3). The predicted equations of the photosynthetic rate (μmol CO2 m−2 s−1), transpiration (m mol H2O m−2 s−1), intercellular CO2 concentration (μmol CO2 mol−1), stomatal conductance (mol H2O m−2 s−1) and leaf temperature were obtained by multiple regression analysis of the measured data. The average 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 lower than that under C2 and C3 during the production period. The average of photosynthetic rate values were 16.61 ± 5.49, 15.51 ± 5.18 and 14.91 ± 4.78 μmol CO2 m−2 s−1 for films C1, C2 and C3, respectively. While, the transpiration rate and the intercellular CO2 concentration under (C1) were higher than those under C2 and C3 during the production period. Therefore, fruit and yield traits increased under C1 followed by C2 and then by C3 of greenhouses covers. It can be concluded that the greenhouses plastic covering material has a great influence on the internal environmental conditions, physiological processes and productivity of cucumber plants.