UV-B RADIATION EFFECT ON PHOTOSYNTHESIS, GROWTH AND CANNABINOID PRODUCTION OF TWO Cannabis stavic CHEMOTYPES: by John Lyndon, USDA-ARS, Southern Weed Science Laboratory, P. O. Box 350, Stoneville, MS, 38776, USA: Alan H. Teramura, Department of Botany, University of Maryland, College Park, MD, 20742, USA., & C. Benjamin Coffman, USDA-ARS, Weed Science Laboratory, AEQ, I, Beltsville, MD, 20705, USA: Received August 29, 1986, accepted February 24, 1987: page 201 Although the mechanism is unknown, a relationship exists between cannabinoid content and the attitude altitude at which C. sativa is grown. Mobark et al., (197 suggested that the high-altitude environment was responsible for an increased population of propyl cannabinoids in plants grown in 1300m. The average total cannabinoid content of wild, mature (flowering) Indian C. sativa from elevations between 250m and 1000m was 2.43% (by dry weight); between 1000 m and 2000m was 3.01%; and above 2000m Was 1.39% (Turner et al., 1979). The cannabinoid content in four out of five of these mature Indian C. sativa variants decreased when grown at sea level in Mississippi, USA. One likely factor which may be of significance to cannabinoid production in both high-altitude and tropical environments is ultraviolet radiation. page 202 Pate (1983) reported that C. sativa populations originating from high UV-B environment contained little or no cannabidiol (CBD) but high levels of delta 9 - tetrahydrocannabinol (delta 9 - THC), while the opposite was true for population from low UV-B environments, and proposed that the two distinct C. sativa chemotypes (drug and fiber) evolved as a result of selective pressures brought about by UV-B radiation. Fairbairn and Liebmann (1974) reported that the delta 9 - THC content of leaf tissue from UV irradiated greenhouse-grown drug-type C. sativa was 23% greater than non- irradiated greenhouse-grown plants. However, neither the spectral distribution nor the daily dose of UV radiation . The objectives of this study were to test (a) The physiological and morphological insensitivity of both the drug and fiber types of C. sativa to UV-B radiation; and (b) to correlate this insensitivity with a change in production of delta 9 - THC or CBD in drug and fiber type plants, respectively. Material and Methods Page 203 Results....Only the delta 9 THC content in leaf and floral tissues of drug type plants increased significantly with UV-B radiation. page 204 Discussion page 205 The results presented here indicate that both types of vegetative C. sativa are physiologically and morphologically insensitive to UV-B radiation. The increased level of delta 9 - THC found in leaf tissues upon UV-B irritation may account for this insensitivity on the drug type plants. However, fiber-type plants showed no comparable change in the level of CBD which has similar UV-B absorption characteristics). Thus, the contribution of cannabinoids to the UV-B insensitivity in vegetative C. sativa is equivocal. Perhaps the background levels of CBD present in the fiber-type tissues were sufficient to protect the plant from UV-B radiation. Alternatively, other UV-B absorbing compounds such as flavonoids may account for this UV-B insensitivity. Flavonoids are the principle pigments associated with UV radiation greening in plants . Barrett et al (1985) reported the concentration of Cannflavin A (a flavonoid from C. sative) was similar in drug and fiber type leaf tissue, whereas Gellert et al (1974) reported relatively more flavonoids in drug than fiber type plants. Whether the quality and quantity of flavonoids in leaf tissues of the chemotypes in this study were sufficient to account for observed UV-B insensitivity was not determined. It should be pointed out, however that one should be cautions when extrapolating from greenhouse to field conditions in UV-B studies. In addition, when considering the distribution of C. sativa, one cannot overlook the fact that it is one of the oldest cultivated plants known to man. Thus, its present distribution may possibly be an artifact of man's cultural practices. In conclusion, the delta 9 THC content in leaf and floral tissues of greenhouse grown drug-type C. sativa increased linearly with UV-B dose. Other cannabinoids in drug and fiber-type plants were unaffected by UV-B radiation. Both drug and fiber chemotypes were physiologically and morphologically tolerant to UV-B radiation.
and 20% gain in THC could be the making of some absolute hardcore bud, If I grow a strain renown for high THC production anyway, then give the best nuits I can find, whilst grow in a DWC setup, and super boost it with, BUD CANDY, CANNA-BOOST,BLOOMBASTIC and CHA-CHING, a 20% THC gain from a UVB lamp, could be the crucial making of some serious HYBRID bud that surpasses its own genetics, 2 different strains cross breeds and then its baby with the same treatment I am sure would be close to growing pure THC
..... so next to no heat emmiting from the tubes 
I still need to know how long to run them for?? and wether to run them in conjunction with my other lights or to have the UVB's on in the plants night time ( during 12 hours of darkness) ?? - STELTHY
, and since I am experimenting still, I see this as a worthy use of my time, I will take every care to ensure the health and vitality of these ladies and if their health deteriates during the use of UVB then I shall refrain from using them further, Trust me I'll look after them! I take it your impressed by what I've achieved so far?? 
, depending on how long my thermostat takes to arrive, the arrival of my co2 cannister upgrade, and the day I take the plunge and buy these UVB lamps, I may save my urges for trial n error for my next grow?!! so chances are I ll harvest with the set-up I have so far, then experiment further with my next grow, I will Probably grow ALEGRIA + SHARK BREATH on my next go, please write back with any comments REP
, or questions, cheers buddy - STELTHY
