The vegetative growth assists to reproductive responses of Arabic coffee trees in a long-term FACE experiment

In simulation studies of Arabic coffee plants under the future CO 2 conditions, no data about flowering, yield fractions or beverage sensorial have been reported. It was hypothesized that elevated CO 2 (e[CO 2 ]) would improve the leaf-gas exchange responses, assisting in improvement of coffee reproduction. The aim was to estimate leaf-gas exchange dynamics, flowering, fruiting intensity and quality in Coffea arabica grown in long-term FACE experiment under rainfed conditions. Leaf-gas exchanges were followed for five years during vegetative and reproductive stages; flowering was observed at second order axis scale for 4 years; berry production, its fractions and beverage sensorial were estimated at plot scale in the 4th production year under FACE. Young coffee plants did not modify leaf-gas exchange responses under e[CO 2 ] in observed periods, while the adult ones increased leaf-photosynthesis in all observed stages. Stomatal conductance and water use efficiency were higher under e[CO 2 ] than actual [CO 2 ] in some stages of flowering, berry expansion and ripping, benefited from higher water content over the soil profile in advanced years of FACE. Elevated CO 2 mitigated the effects of anomalous drought and high temperatures in rainy season, reducing the abnormal reproductive structures rate. Under e[CO 2 ], the intense leaf-photosynthesis did not improve the yield or sensorial beverage quality in 4th production year, but a fraction of green berries, indicating flowering delay or prolongated ripening. The e[CO 2 ] supported species survival during short intensive drought through high carbon investments in reproduction, while long/anomalous droughts reduced the fraction of flower abnormalities, indicating carbon investments in individual plant survival.