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 m(2), North-South direction and with wet-pad and fan cooling system were covered by either one of the 200 mu m thickness plastic films; newly developed NIR-reflective film (C-1) and two commercial films (C-2 and C-3). The predicted equations of the photosynthetic rate (mu mol CO2 m(-2) s(-1)), transpiration (m mol H2O m(-2) s(-1)), intercellular CO2 concentration (mu mol 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 degrees C, 23.80 +/- 2.26 degrees C, 25.42 +/- 2.41 degrees C and 31.12 +/- 4.30 degrees C for films C-1, C-2, C-3 and outside respectively. The results revealed that vapour pressure deficit (VPD) under (C-1) was lower than that under C-2 and C-3 during the production period. The average of photosynthetic rate values were 16.61 +/- 5.49, 15.51 +/- 5.18 and 14.91 +/- 4.78 mu mol CO2 m(-2) s(-1) for films C-1, C-2 and C-3, respectively. While, the transpiration rate and the intercellular CO2 concentration under (C-1) were higher than those under C-2 and C-3 during the production period. Therefore, fruit and yield traits increased under C-1 followed by C-2 and then by C-3 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. (C) 2015 Elsevier B.V. All rights reserved.