Photosynthetic performance of two coffee species under drought
1997
Da Matta, F.M. | Maestri, M. | Barros, R.S. (Universidade Federal de Vicosa (Brazil). Dept. de Biologia Vegetal)
In 14 months old Coffea arabica cv. Red Catuai and C. canephora cv. Kouillou irrigation was withheld until the leaf pre-dawn water potential was about -1.5 and -2.7 MPa. Under mild stress, net photosynthetic rate (PN) decreased mainly as a consequence of stomatal limitations in Kouillou, whereas such decreases were dominated by non-stomatal limitations in Catuai. Under severe drought, further decreases in PN and apparent quantum yield were not associated to any changes in stomatal conductance in either cultivar. In both cultivars the initial chlorophyll (Chl) fluorescence slightly increased with no changes in the quantum efficiency of photosystem 2. In response to rapidly imposed drought, the Chl content did not change while saccharide content increased and starch content decreased. Photoinhibition was enhanced under severe water deficit, especially in Catuai. In this cultivar the O2 evolution did not resume upon reversal from photoinhibition, in contrast to the complete recovery in Kouillou.
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