GROCALC is a suite of electronic grower decision support tools that include ALKCALC, FERTCALC and PGRCALC. These programs are useful for making calculations related to greenhouse crop culture including water acidification requirements, fertilizer solution and plant growth regulator (PGR) mixing. However, there are few or no tools available to help make calculations related to the greenhouse light environment.
Although light is frequently discussed in terms of instantaneous values such as the foot candle (f.c.) or micromole (µmol∙mˉ²·dˉ¹), the total photosynthetic light over the course of a day, known as the daily light integral or DLI, is becoming the preferred way to quantify light in a greenhouse. However, calculating DLI can be a daunting task. To continue the development of useful decision support tools, we created DLICALC (http://Extension.unh.edu/Agric/AGGHFL/dlicalc/index.cfm) as a tool to help growers manage the photosynthetic light environment.
A Solution For Growers
The inspiration for creating DLICALC came from growers’ frequent questions about using supplemental lighting to increase the DLI. Some of the most frequently heard questions were, “How much photosynthetic light are my lamps contributing to the overall DLI in my greenhouse?” and “How long should I run my lamps if I want to increase the DLI by XX mol∙mˉ²·dˉ¹?”
Since many growers still measure light in foot candles (f.c.) and, less often, micromoles (µmol∙mˉ²·dˉ¹), it is difficult to integrate those types of instantaneous light measurements into an integrated unit such as mol∙mˉ²·dˉ¹.