Table_1_Elevated UV photon fluxes minimally affected cannabinoid concentration in a high-CBD cultivar.docx

Ultraviolet photons (UV) can damage critical biochemical processes. Plants synthesize photo-protective pigments that absorb UV to minimize damage. Cannabinoids absorb UV, so increased UV has the potential to increase cannabinoid synthesis. Studies in the 1980’s provided some evidence for this hypothesis in low-cannabinoid cultivars, but recent studies did not find an increase in cannabinoid synthesis with increasing UV in high-cannabinoid cultivars. These studies used low UV photon fluxes, so we examined the effect of higher UV photon fluxes. We used fluorescent UV lights with 55% UV-B (280 to 314 nm) and 45% UV-A (315 to 399 nm). Treatments began three weeks after the start of short days and continued for five weeks until harvest. Established weighting factors were used to calculate the daily biologically effective UV photon flux (UV-PFDBE; 280 to 399 nm). Daily UV-PFDBE levels were 0, 0.02, 0.05, and 0.11 mol m-2 d-1 with a background daily light integral (DLI) of 30 mol m-2 d-1. This provided a ratio of daily UV-PFDBE to DLI of 41 to 218% of summer sunlight in the field. Cannabinoid concentration was 3 to 13% higher than the control in UV treated plants, but the effect was not statistically significant. Fv/Fm and flower yield were reduced only in the highest UV treatment. These data support recent literature and lead us to conclude that an elevated flux of UV photons is not an effective approach to increase cannabinoid concentration in high-cannabinoid cultivars.

紫外光子（UV）能够损害关键的生物化学过程。植物合成光保护色素以吸收UV光，从而最小化损害。大麻素能够吸收UV光，因此增加UV光有可能提高大麻素的合成。20世纪80年代的研究为这一假设在低大麻素品种中提供了一些证据，但最近的研究并未发现在大麻素含量高的品种中随着UV光的增加而提高大麻素合成的现象。这些研究使用了低UV光子通量，因此我们考察了更高UV光子通量的影响。我们使用了含有55%的UV-B（280至314纳米）和45%的UV-A（315至399纳米）的荧光UV灯。处理始于短日照开始后的三周，并持续五周至收获。使用已建立的权重因子计算每日生物有效UV光子通量（UV-PFDBE；280至399纳米）。每日UV-PFDBE水平为0、0.02、0.05和0.11摩尔平方米每天，背景每日光照积分（DLI）为30摩尔平方米每天。这提供了每日UV-PFDBE与DLI之比为41至218%的夏季日光强度。在UV处理植物中，大麻素浓度比对照组高3至13%，但效果不具有统计学意义。仅在最高UV处理中，Fv/Fm和花朵产量有所降低。这些数据支持近期文献，并使我们得出结论：提高UV光子的通量并非是提高高含量大麻素品种中大麻素浓度的有效途径。