The Effect of Low-Haze Diffuse Glass on Greenhouse Tomato and Bell Pepper Production and Light Distribution Properties

Abstract

Diffuse greenhouse glass can increase the production and growth of several crops, by scattering the incoming direct sunlight, which results in a better and more homogeneous light distribution in the crop canopy. Tomato and bell pepper growers in Belgium tend to install low-haze diffuse glass with a double anti-reflection (AR) coating. These glass types have a limited diffuse effect but have a higher light transmission compared to standard float glass. Therefore, tomato growers often increase stem density to maximize light interception. However, a denser crop could counteract the positive effects of diffuse glass on the vertical light distribution. In this study, the effect of low-haze diffuse glass with an AR coating was evaluated for different cropping densities for tomato and bell pepper taking into account the vertical light distribution throughout the crop canopy. Tomato plants with two stem densities (3.33 and 3.75 stems.m−2) and bell pepper plants (with only one stem density of 7.1 stems.m−2) were evaluated in a greenhouse compartment with diffuse and reference float glass during a full growing season. For tomato, a significant production increase of 7.5% was observed under diffuse glass during the second half of the growing season but only for the low stem density. The benefit of diffuse glass appears most relevant during sunny clear skies and on the sun-side-facing rows of the crop. For bell pepper, no significant production increases were noted between regular float or diffuse glass, because a bell pepper crop is typically covered with thermal screens to prevent sunburn on the fruits during sunny days. The vertical light distribution and the usefulness of AR-coated diffuse glass depends on the crop type and should be optimized accordingly by altering the stem density, leaf pruning strategy, row orientation, or crop variety.

Seeing light from a different angle: the effects of diffuse light on the function, structure, and growth of tomato plants

“…In general, our results would suggest that diffuse light produces greater vegetative biomass despite no noticeable effects to standard relative growth rate measurements. This is supported by literature that find modest (2-10%) increases in diffuse light whole-plant, flower, and fruit biomass in a variety of commercially important species such as roses, chrysanthemum, anthurium, and tomato (Markvart et al 2010, Garcia Victoria et al 2021, Elings et al 2012, Holsteens et al 2020). It should be noted that these gains in biomass have not always led to greater fruit production because of the allocation tradeoff to shoots, roots, and fruits.…”

Near-infrared Reflective Diffusion Coating Is Beneficial for Asparagus Summer Production in a Simple Plastic Greenhouse

“…Therefore, the asparagus management model can be modified for promoting the diffused effect. Moreover, diffused light can be more beneficial for crop biomass production compared with direct light over %750 mmol•m À2 •s À1 (Earles et al, 2017;Holsteens et al, 2020).…”

“…Previous studies have indicated that compared with direct light, the aforementioned coverings or materials could increase the diffuseness or scattering of light, resulting in a more homogeneous light distribution, lower shading, and deeper light penetration into the crop canopy without affecting transmission (Li and Yang, 2015;Liang et al, 2020). Moreover, plants cultivated under diffused light showed increased photosynthetic efficiency, lower photoinhibition, and higher biomass production (Elings et al, 2012;Holsteens et al, 2020;Li et al, 2014).…”

Modelling the interaction between a pest (Aculops lycopersici), two predators (Pronematus ubiquitus and Macrolophus pygmaeus) and climate variables: a 3‐year greenhouse study in a tomato crop

“…Furthermore, we included different kinds of climate factors in the previous week to the model: temperature (°C) (Temp), maximum and minimum temperature (Tmax, Tmin in °C), relative humidity (RH in %), maximum and minimum relative humidity (RHmax, RHmin in %), vapour pressure deficit during the night and day (VPDnight, VPDday in kPa), day length (including artificial light) (Light as a proportion), radiation (Rad: sum of weekly μmol m −2 s) and the categorical variable lit or unlit (Lit). The variable radiation was calculated as the weekly sum of 80% of the outside radiation, which covers the loss of the light transmission through the glass, 44 plus 700 μmol m −2 s per week from the artificial lights when lit.…”