GREENHOUSE COVER COMPARISON ON TOMATO GROWTH AND

Abstract

Greenhouse cultivation allows higher yields than those obtained in the open field, due to better control of the environment. The hypothesis was that the colour and characteristics of the greenhouse cover material for tomato production affect the transmission of solar radiation received by the plants, and therefore growth and yield. The objective was to evaluate the intensity and spectral distribution of transmitted solar radiation (Photosynthetic active radiation, PAR) through four greenhouse covers with different physical characteristics and colour, on relative chlorophyll content, photosynthesis rate, growth and yield of a tomato crop (Solanum lycopersicum L.). To measure the intensity of solar radiation (400 to 700 nm) transmitted by each cover, quantum sensors were installed inside tunnel-type greenhouses; the spectral characteristic in the same solar radiation band was determined with a spectroradiometer. The effect of the covers was analysed with a completely randomized blocks design with treatment replicates within each tunnel greenhouse. Plants in greenhouses with red and blue diffuse high-density polyethylene covers received less solar radiation in the 400 to 700 nm wavelength band. Also, the radiation of 400 to 550 nm received by the plants in the greenhouse with the red cover was much lower than that received by plants under other covers. The plants in the blue polyethylene covered greenhouse received less solar radiation in the interval 600 to 700 nm. This did not affect the chlorophyll content nor the carbon dioxide assimilation rate. However, there was a significant increase (p≤0.05) in plant height, but with a smaller stem diameter. As well as there was a higher yield, expressed in number of fruits per plant, weight and larger fruit size in plants under polyethylene tunnels with red and blue pigmentation.