Articles
Quantifying the effects of hortiscatter in greenhouse cover materials on crop yield
Article number
1423_12
Pages
87 – 94
Language
English
Abstract
To control and optimize light entering the greenhouse, different types of glass, screens, and coatings are available.
Diffuse cover materials can change the geometrical distribution of incoming sunlight, improving the horizontal and vertical light distribution in the crop.
Recently, the unit hortiscatter has been defined to quantify light scattering by cover materials, and it provides information on the geometrical distribution of photons.
Diffuse covering materials have proven to increase crop yield in many crops, but in these past studies different glass materials were used, resulting in different levels of diffusivity and light transmission, thereby potentially affecting crop yields.
The goal of this research was to establish a quantitative relation between hortiscatter, as a measure for diffusivity, and crop yield of different crops, and thus to establish a rule of thumb for the amount of crop yield increase per unit hortiscatter.
A literature review was conducted of earlier studies that compared growth under diffusive with growth under clear glass covers.
Also, the cover materials used in these studies were measured to determine hortiscatter and hemispherical light transmission.
To account for differences in hemispherical light transmission that accompany different hortiscatter levels, yield was divided by hemispherical light transmission.
The difference of this ratio between diffuse and reference material was used to compare data sets for 11 crops.
On average, yield increased by 1.8% for every 10% increase in hortiscatter.
For tomato and cucumber this was 2.1 and 2.2%, respectively.
We conclude that a quantitative relationship between hortiscatter and crop yield can be established.
Diffuse cover materials can change the geometrical distribution of incoming sunlight, improving the horizontal and vertical light distribution in the crop.
Recently, the unit hortiscatter has been defined to quantify light scattering by cover materials, and it provides information on the geometrical distribution of photons.
Diffuse covering materials have proven to increase crop yield in many crops, but in these past studies different glass materials were used, resulting in different levels of diffusivity and light transmission, thereby potentially affecting crop yields.
The goal of this research was to establish a quantitative relation between hortiscatter, as a measure for diffusivity, and crop yield of different crops, and thus to establish a rule of thumb for the amount of crop yield increase per unit hortiscatter.
A literature review was conducted of earlier studies that compared growth under diffusive with growth under clear glass covers.
Also, the cover materials used in these studies were measured to determine hortiscatter and hemispherical light transmission.
To account for differences in hemispherical light transmission that accompany different hortiscatter levels, yield was divided by hemispherical light transmission.
The difference of this ratio between diffuse and reference material was used to compare data sets for 11 crops.
On average, yield increased by 1.8% for every 10% increase in hortiscatter.
For tomato and cucumber this was 2.1 and 2.2%, respectively.
We conclude that a quantitative relationship between hortiscatter and crop yield can be established.
Authors
G. van Steekelenburg, S. Hemming, E. Kaiser, E. Heuvelink
Keywords
diffuse light, direct light, hortiscatter, hemispherical light transmission
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