Diffused Albarino glass gives higher light transmission and more stable greenhouse temperature

In 2015 Christophe Rousse built a new greenhouse using diffused Albarino glass from Saint-Gobain Cultilene. This French tomato grower is getting definite advantages of various kind. ‘More light in the greenhouse and the greenhouse temperature is more stable. This is giving me both more yield and better fruit quality’.

Christophe Rousse grows cherry, cocktail and vine tomatoes in Nouvoitou which is near the city of Rennes in Brittany (France). Rousse, who is the chairman of the Solarenn growers’ cooperative, expanded his operations substantially in 2015. ‘We then added a greenhouse six metres high of 1.6 hectares, so we now have 3.7 hectares in total. The older greenhouses were all 5 or 5.5 metres high’, said the grower.

The new greenhouse is glazed with diffused Albarino glass from Cultilene. Rousse looked at what various Dutch companies had to offer in the way of Albarino glass. To be guaranteed the best possible light transmission, he bought Albarino diffused glass with a haze factor of 80% and with an anti-reflective coating on both sides. ‘This cost substantially more than conventional glass’, said Rousse. ‘But this is being compensated for by one percent more light that produces an average of one more kilo of tomatoes per m². To get the best out of the diffused glass, we switched to growing Clodano vine tomatoes, a variety that reacts well to this extra light.’

Positive effects

Rousse can look back over the last two years with satisfaction: he is very pleased with the results produced by the diffused Albarino glass. ‘More light gets into the greenhouse. This guarantees increased production and a more stable climate. This is a big advantage as we can have pretty hot summers in this area’, he adds. ‘The light transmission is also perfect even with some condensation on the greenhouse roof. I’m also happy with the light dispersion; there’s only a minimal shadow effect and all the leaves receive the maximum amount of sunlight. This helps photosynthesis.’

The grower has also noticed an effect on temperature. ‘In the new greenhouse, it’s always cooler than in the other greenhouses where we’ve used a diffused coating. At the end of June, for example, the outside temperature was 38 degrees. In the greenhouse with Albarino glass, it was 33 degrees while the temperature in our other greenhouses rose to 35 to 36 degrees. This is not only good for the crop – our workers appreciate it, too. As well as this, the effect of the diffused glass is optimal all year round.

Diffused coatings, however, have to be applied in March and removed in September. Another problem is that the companies that apply these coatings are sometimes short on time so that the coatings aren’t always applied evenly.

Rousse says that diffused glass also has a positive effect on the crop. ‘We’ve noticed good flowering and fruit set over the last two years. Water consumption follows the light curve, even when it’s really hot. The RH is always good. And the stopping of direct light in the greenhouse means no leaf scorch. The beautiful white roots are just one sign that the plants have more vigour.

The grower also mentioned a positive effect on fruit quality. ‘The tomatoes have a even colour throughout the truss’, said Nathalie Rivereau, the person in charge of growing at Rousse’s company.

Increased production

The grower said that these advantages are also giving increased production. ‘In 2016, when we planted on February 4th we harvested 66 kilos per m². In 2017, our production at the end of August was 4 kilos more per m² than the previous season. Although it’s difficult to compare the new greenhouse with the older ones, I’d bet that using diffused glass in the Rennes area would give an average of two to five more kilos per m².’

The only disadvantage, according to Rousse, is that diffused glass with a high haze factor decreases light transmission. An early planting in November or December means a slight delay. ‘But we catch up quite quickly.’

At the end of the season, the grower cleans the greenhouse roof with plain water. ‘It’s important to use a product that’s not too aggressive; this stops the anti-reflective coating from being damaged. Next year, I’ll probably use AmberClean from Cultilene. This is a cleaning product made specifically for diffused glass’.

 

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