Physiological Responses of Coffee (Coffea Arabica L. VAR. Castillo) Plants to Biochar Application Under Water Deficit Conditions

Drought is one of the main abiotic stresses in coffee crop, and the use of biochar (BC) has been considered an alternative to mitigate this kind of stress. Plants of the Castillo variety were grown in pots and PVC pipes filled with silt loam soil in two separate experiments to evaluate the effect of the coffee pulp biochar application on the physiological responses under water deficit conditions. Four different BC doses (0, 4, 8, and 16 t ha-1) were incorporated. Water deficit was imposed through the progressive reduction irrigation (25%, 50%, 75%, and 90% of water lost via evapotranspiration). Gas exchange, maximum quantum yield of PSII (Fv/Fm), biomass, and water status were measured. Reduced irrigation (RI) negatively affected Fv/Fm , leaf gas exchange, biomass, and water status. 8 t ha -1 (BC) increased photosynthesis in both well-irrigated (WI) plants (6 µmol m-2 s-1) or with RI (3.5 µmol m-2 s-1) compared to 0 t ha -1 BC (RI: 1.8 µmol m-2 s-1 and WI: 3.9 µmol m-2 s-1). To summarize, 8 t ha-1 BC can be a recommended practice for coffee production not only to capture carbon and reintroduce it to the soil, but also to alleviate the effects of moderate water deficit.