Enhanced Efficiency Phosphorus Fertilizer Impact on Physiological Characteristics of Coffee Seedlings

The effects of phosphorus (P) nutrition on various aspects of photosynthetic metabolism have been examined for coffee plants (Coffea arabica) grown under greenhouse conditions. The experimental design was completely randomized, and the treatments were carried out in a 2 × 5 factorial scheme: two P sources [Triple Superphosphate - TSP (46% P2O5) and Policote coated TSP - TSP + Policote (43.7% P2O5)] and five P rates (0; 5; 10; 15 and 20 g P2O5 plot-1), with three replications. The net photosynthetic rate (A), the leaf temperature (LT), the atmospheric CO2 concentration (Ca), the stomatal conductance (gs), the transpiration rate (E), the substomatal CO2 concentration (Ci) and carboxylation efficiency (Ce) were measured in the youngest fully expanded leaf, with the use of an infrared gas analyzer. All photosynthesis measurements were affected by P fertilization. P fertilization increased net photosynthetic rate, leaf temperature, substomatal CO2 concentration, stomatal conductance, transpiration rate, and carboxylation efficiency. Policote coated P fertilizer resulted in a higher net photosynthetic rate, leaf temperature, stomatal conductance, and transpiration rate than conventional P fertilizer. The data indicated that Policote coated P fertilizer, a kind of enhanced efficiency P fertilizer (EEPF), alters the plant’s photosynthetic carbon metabolism, explaining higher crop development and yield resulted from this EEPF.