The Potential Photoprotective Ability of Copper Pthalocyanine.

Chlorinated copper phthalocyanine (Pigment green 7) applications have been cited to produce physiological benefits in cool season turfgrasses. This pigment was first thought to result in healthier turfgrass when combined with various fungicides; however, its ability to protect photosynthetic electron transport may be of more importance. Not only can photosynthetic machinery transform light energy into reductant and ATP, but protein complexes like photosystem II can also produce relatively high concentrations of reactive oxygen species under physiological stress. Pigment green 7 may have the ability to reflect excess visible light and harmful ultra-violet light; therefore decreasing pressure on photosynthetic machinery and helping to maintain homeostasis. The purpose of this research was to determine if applications of pigment green 7 could decrease photosynthetic stress on field and greenhouse grown creeping bentgrass (Agrostis stolonifera). The experiment was conducted using a split plot design, where half the plots were treated weekly with amicarbazone at a concentration of 3 mg L-1 in order increase photosystem II photoinhibition. Pigment green 7 was applied in a dose dependent manner with concentrations ranging from 250 – 2,000 mg L-1 on a 14 day interval. Daconil Ultrex® treatments were also included with and without pigment green 7 to evaluate the potential effects of inert white additives. Photochemical efficiency (Fv/Fm) was measured weekly three times during the day; morning, mid-day, and evening. Results show 2,000 mg L-1 pigment green 7 significantly increased Fv/Fm compared to an untreated control for data taken in the morning, mid-day, and evening. These results have also been consistent for both field and greenhouse experiments; however results do not show dose dependence in that only high concentrations of green 7 provide photoprotection. Not only do concentrated applications of green 7 increase photochemical efficiency, but data also show a significant increase in total chlorophyll without a shift in chlorophyll a:b. Morphological changes have also been visible; plots treated with higher concentrations of green 7 are physically more dense and produce greater biomass.