“Do you think it is necessary to add UV chips to the LED grow light?”
Only if that LED grow light is specifically created to properly test the effects of UV light on cannabis. Which to date has never been done to an extend that would lead to adding UV to commercial production lights. The research from the 80s can be dismissed and should lead to only one conclusion: that it’s worth researching further. Personally I believe it may be helpful for specific varieties under specific circumstances and with very specific dosage, and thus is generally not useful. It would also be something to combine with an otherwise perfect grow, which unfortunately are still rare.
While THC may be a result of cannabis having evolved to protect itself against UV (there’s some truth to the mountain reference the previous poster mentioned), it does not follow UV will increase that further. Just as we land animals don’t grow extra limbs if we stay on land. Just as red plant doesn’t get any more red if you surround it with predators.
Most importantly, the THC % isn’t the only relevant factor. Certain light conditions lead to an increased THC% not because of an increase of THC, but a decrease in other plant material. This is sometimes evident in results from (C)MH too. Frostier yet smaller buds.
If for example you want to produce THC oil/concentrates, would you rather have 3 ounce of 15% THC bud, or 2 ounce of 20% THC bud. In other words, while you may push the THC% a bit with additional UV light, if you end up harvesting less in weight it may not be worth it after all. On the other hand, if you are in a competitive market where a higher THC% means you can sell your product more easily... Point is, this would have to be tested more extensively, and properly before a solid answer can be given to the question at hand.