Ultraviolet radiation has detrimental effects on plants and levels are expected to rise through mid-century. Photosystem II is the most vulnerable site in chlorophyll affecting productivity. The purpose of this study was to evaluate leaf-level interactions with UV radiation in tropical and temperate crops. The species sampled were (1) citrus, (2) banana, (3) coffee, (4) pineapple, (5) olive, (6) grape, (7) apple, and (8) tobacco. Plants of each species were placed beneath a polycarbonate structure that excluded 98 of UV radiation, but maintained ambient environmental conditions and transmitted 96 PAR (UV- treatment). Plants of each species were maintained nearby under ambient conditions (i.e., without a UV filter; UV+ treatment). The maximum quantum efficiency (f /F_m) was measured with and without UV radiation at the time of measurement. Photosynthesis (A) and quantum efficiency (/,) were measured in the same experimental system using only apple, citrus, banana, and coffee. Only banana and coffee did not fully recover their F/F_m potential when they had not been previously exposed to UV, indicating that these species probably had not induced background repair mechanisms. The AF/F_m is small in magnitude for banana and coffee due to UV treatment but when A is measured, the treatment impact has greater magnitude and banana and coffee A do not recover and coffee continues to decline while banana appears to stabilize. Banana and coffee have the potential to benefit from cultural practices that reduce the UV irradiance to the leaf or canopy surface.
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