Influence of UV-B radiation on growth and physiological responses of arabica coffee seedlings across altitudinal gradients
摘要
This study evaluated the effects of solar UV-B (Ultraviolet-B) radiation on coffee seedlings at different altitudinal ranges in a tropical environment. A field experiment, conducted using a randomized complete block design, tested four coffee varieties—Fayette, Odisha, Koti, and Hangafa—under natural UV-B radiation and UV-B-blocking sheets at altitudes of 1450, 1850, and 2150 m, with three replications. The results revealed that altitude significantly influenced most growth parameters, except for specific leaf area and primary branch girth. The interaction between altitude and coffee variety affected plant height, primary branch length, and internode length (at p < 0.001, 0.01 and 0.05, respectively), with plant height and primary branch length decreasing as altitude increased. Altitude also impacted leaf area and physiological parameters such as photosynthetic rate (Pn) and transpiration rate. In contrast, the interaction of UV-B and altitude influenced stomatal conductance and intercellular CO2 levels. These findings demonstrate that coffee varieties respond differently to solar UV-B radiation at different altitudes. This highlights the need for location-specific coffee breeding/genetic selection/ in tropical environments to address adaptation to climate change, particularly in relation to increased UV radiation.