Insight into daily plant performance presents opportunities to increase production

Optimal production starts with good light distribution; this ensures that the plant receives maximum light (both sunlight and grow light). But it’s also important that the plant makes optimal use of the amount of light available. “Many growers look mainly at the radiation sum (measured outside), which the crop should receive per day, per week or per production cycle, according to a principle that has been empirically determined in the past,” says Stéphane André, Grow Light Performance Consultant at Hortilux. “However, it’s more valuable to know the extent to which the plant converts the available grow light into production – how many grams per mole of PAR light it produces. After all, this is the light that actually contributes to the plant’s growth. You obtain insight into this light effectivity by dividing the number of kilos harvested by the light sum (in moles of PAR) that was realised during the fruit’s growing phase.”

Various factors

There are various factors that influence light effectivity (also known as Light Use Efficiency (LUE)). “In addition to grow light, there are other factors that impact on the extent to which the plant makes use of the available light. These are the relative humidity, the temperature, the CO2 level in the greenhouse, and the Leaf Area Index – the number of square metres of leaf per square metre of ground surface,” says Hans de Vries. De Vries is also a Grow Light Performance Consultant at Hortilux. “The balance between these elements ultimately determines how a plant performs. In some cases, for example, a higher CO2 dosage can result in higher production with the same amount of light.”

Light efficiency and assimilate sum

While light effectivity is very useful, it can only be determined in retrospect, after harvesting. No substantiated adjustments have been made during cultivation – until now. Two new Hortilux tools are set to change this: the light efficiency and the assimilate sum give insight into the plant’s light utilisation during cultivation. “The light efficiency indicates how the plant performs in the available light and under the current climate conditions,” André says. “A special graph in HortiSense shows this percentage in a dynamic response curve. A score of 100% indicates the maximum conversion of light into sugars. The assimilate sum is in fact the result of the light efficiency: this sum shows the amount of sugars produced.”

Targeted adjustment

Just like the light effectivity, these matters are made transparent in the HortiSense digital platform. For this purpose, the parameters that determine the use of the light are continuously monitored during cultivation: the amount of PAR light available, the relative humidity, the temperature, the CO2 level in the greenhouse, and the Leaf Area Index. “This gives the grower insight into daily plant production during cultivation, as well as into what the plant does with the amount of light it receives. This in turn means that the lighting and other growth parameters can be adjusted in a targeted way, optimising the production of sugars and thus the light utilisation. In short: insight into daily plant performance presents opportunities to increase production.”

Would you like more information on the possibilities for your crop?

For more information, please contact Hortilux’s Grow Light Performance Consultants: Stéphane André (06 -10282335 or s.andre@hortilux.com) and Hans de Vries (06-57011488 or h.devries@hortilux.com).