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

Abstract

Physiological response of coffee plants to their environment was observed through leaf photosynthetic measurement. The leaf photosynthetic efficiency of coffee plants grown in agroforestry was identified at different elevations. Each elevation has variations in ambient air temperatures. OJIP transient fluorometry recorded that the photosynthetic efficiency responds differently at different elevations. The plants grown at 1200 MASL with higher ambient air temperatures experienced a rise in the OJIP steps of fluorescence transients, indicating the closure of some of the PSII reaction centers. However, the coffee plants grown at 1300 MASL, with lower ambient air temperatures and higher exposure to solar radiation, had better electron transport, as indicated by lower OJIP fluorescence transients, when compared to coffee plants grown at 1200 MASL. Regarding the OJIP fluorescence traits, it was found that the plants promoted better photosynthetic efficiency in the area with higher solar radiation and lower ambient air temperatures.