THE INFLUENCE OF TWO DIFFERENT POLYETHYLENE FILMS ON GREENHOUSE MINIMUM TEMPERATURES AND ON THE GROWTH AND YIELD OF A TOMATO CROP
Temperature and productivity differences were compared between two wooden frame chapel type greenhouses with a winter tomato crop (Cvs. Carmelo and Fandango) during the November-June period at Lisbon. One of the greenhouses was cladded with IF-PE (low infra-red transmissivity PE) and the other with UV-PE (regular ultraviolet treated PE). Minimum soil temperatures (20 cm deepness) and air temperatures at 10 cm level decreased from under IF-PE to UV-PE and to the open-air. At 50 cm and 150 cm minimum air temperatures were always higher at the open-air then under UV-PE. Under cloudy sky conditions minimum air temperatures at 50 cm and 150 cm were equivalent in the open-air and under the IF-PE. However those two temperatures were higher in the open-air with clear sky. Inside the greenhouses minimum air temperatures were higher near the ground (10 cm) than at 50 cm and 150 cm. Open-air temperature stratification had an inverse gradient. Tomato in the IF-PE greenhouse had better pollen quality, earliness and fruit-setting and lower number of flowers per inflorescence. Total yield and fruit size was similar in both greenhouses.
Maia, M.B., Monteiro, A. and Meneses, J.F. (1990). THE INFLUENCE OF TWO DIFFERENT POLYETHYLENE FILMS ON GREENHOUSE MINIMUM TEMPERATURES AND ON THE GROWTH AND YIELD OF A TOMATO CROP. Acta Hortic. 263, 265-274