Ambient air temperatures and solar radiation affect OJIP fluorescence transients of coffee plants in an agroforestry system

Physiological response of coffee plants to their environment was observed throughleaf photosynthetic measurement. The leaf photosynthetic efficiency of coffee plantsgrown in agroforestry was identified at different elevations. Each elevation has vari-ations in ambient air temperatures. OJIP transient fluorometry recorded that thephotosynthetic efficiency responds differently at different elevations. The plantsgrown at 1200 MASL with higher ambient air temperatures experienced a rise in theOJIP steps of fluorescence transients, indicating the closure of some of the PSII reac-tion centers. However, the coffee plants grown at 1300 MASL, with lower ambientair temperatures and higher exposure to solar radiation, had better electron trans-port, as indicated by lower OJIP fluorescence transients, when compared to coffeeplants grown at 1200 MASL. Regarding the OJIP fluorescence traits, it was foundthat the plants promoted better photosynthetic efficiency in the area with higher solarradiation and lower ambient air temperatures