Maximum Yield Cannabis USA August / September 2017 | Page 22

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Since the legalization of recreational marijuana in Colorado and Washington State in 2012 , there ’ s been an eruption of companies developing products to help commercial growers cultivate , process , and dispense the controversial benefits of cannabis . For those engaged the in the underground market last couple of decades , it is both an opportunity and a challenge to serve the greater good of their dedicated hobby-turned-commercial clientele . The new wave of legalization has now put a burden on certain resources . The use of electricity and water , two of the main ingredients needed to grow successfully indoors , has come under scrutiny . Regulatory standards are being established in such a manner that a one-size-fits-all philosophy may stifle the innovation and creativity that once engaged this market .

Regulatory standards are being established in such a manner that a one-size-fits-all philosophy may stifle the innovation and creativity that once engaged this market .”
Is History a Good Lesson to Follow ?
The debate on finding this one measurement has still not been settled . There are factions who want to follow in the footsteps of what has happened in the general lighting market , where commercial LED lighting fixtures and residential lamps are categorized by lumens per watt ( LPW ). The LPW metric is based upon the photopic visual acuity of humans . That is where the term “ lumens are for humans ” originated . More lumens for each watt of energy mean a greater ability for humans to see in the most energy-effective manner … sort of . But let ’ s not go there for now . Just take note that LPW does not define the quality of light , only an amount per unit of energy . While trying not to bog you down with the science of lighting , there is something for you to understand . The LPW metric , while suitable for humans , does not carry the same suitability of visibility for other animals , like cats , dogs , horses , or even snakes . LPW is the efficacy of either a bare lamp measured in an integrating sphere and reported in a certified photometric report , or an HID or LED fixture measured by a goniophotometer . HID fixtures are reported in relative terms . LED fixtures are characterized in absolute terms , as the system is power and temperature dependent . But this article is about plants , not humans . So , instead of using LPW as we do in the general lighting industry , let ’ s talk about terms with which growers are familiar . To understand PPF , you must first know where it comes from and why it was coined . The McCree Curve represents the average photosynthetic response of plants to light energy , known as photosynthetic active radiation ( PAR ). The McCree Curve , also known as the Plant Sensitivity Curve , begins at 350 nanometers ( nm ) and extends to 750 nm .
Figure 1 V : relative luminous efficiency of equal incident radiant fluxes as a function of wavelength , for the C . I . E Standard Photometric Observer ( 6 ). P : relative photosynthetic efficiency of equal absorbed quantum fluxes , as a function of wavelength , for average green leaf ( 8 ) McCree KJ ( 1973 ) A rational approach to the light measurement in plant ecology .
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