INFLUENCE OF DIFFUSE GLASS ON THE GROWTH AND PRODUCTION OF TOMATO

There is a great deal of interest for diffuse glass in Dutch horticulture ever since higher light transmission values and the diffusing characteristics of diffuse glass have increased production for some crops. Thus an experiment was designed to examine the effects of a variation in haze factors and light transmissions for diffuse glass or a diffuse coating on the growth and production of tomato. The influence of diffuse glass with a haze factor of 45, 62 and 71% and light transmission equal to or greater than that of standard glass, as well as standard glass with a commercial coating with a haze factor of 50% and 6% less light transmission than that of standard glass was compared to that of standard glass. The crops were planted mid-December 2010 and grown to the middle of November 2011. The influence of diffuse light on light interception, crop morphology, photosynthesis and growth was measured and analysed. Light penetrated deeper into the crop resulting in a higher photosynthetic capacity in the lower canopy, but only in winter. Tomato grown under diffuse glass was more generative, transferring more into fruit production than vegetative growth, in comparison to standard glass or coated glass. The production under the three diffuse glass coverings showed a 7-9% increase in June relative to that under standard glass, and retained this increased production to the end of the year, ending with 8-11% more production. The most important reason for the increased production was an increase in individual fruit weight by 5-8 g. Plants grown under diffuse glass or coating were less susceptible to Botrytis spp. during the last months of the crop, possibly due to a higher dry matter content. The coating was applied in the beginning of May and the treatment continued through August when the global radiation diminished and more light was necessary in the crop and the coating was removed. The overall production under the coating was 5% higher than that under standard glass. An estimation of the benefits and consequences of diffuse light characteristics on the growth, development and production of tomato under Dutch conditions are discussed, along with recommendations for the optimal characteristics for diffuse glass.