Ecophysiological responses of coffee plants subjected to water deficit to narrow blossom period in the Cerrado in the state of Minas Gerais, Brazil

Abstract

The objective of this work was to evaluate the effect of different periods of water deficit imposition on narrowing coffee (Coffea arabica) blossom period, as well as on gas exchange, coffee bean yield, maturity, and grain quality. The Catuaí Vermelho IAC 144 and Bourbon Amarelo J9 cultivars were evaluated according to the following treatments: nonirrigated (NI), continuously irrigated (CI), and suspension of irrigation on 7/1/2010 (D1) and on 8/1/2010 (D2), which was restarted on 9/24/2010. About three days after irrigation was restarted, a “blossom rain” was registered, with 69 mm precipitation. The pre‑dawn leaf water potential (Y_pd) of the cultivars Catuaí Vermelho IAC 144 and Bourbon Amarelo J9, on 9/22, was of ‑0.59 and ‑0.82 MPa, ‑0.53 and ‑0.79 MPa, and ‑0.34 and ‑0.49 MPa for the NI, D1, and D2 treatments, respectively. The maximum percentage of flower buds at the E4 stage, right before rainfall occurrence, was not affected by the water deficit levels imposed during winter, regardless of the cultivar. The moderate water deficits imposed by the treatments (Y_pd ~ ‑0.80 MPa) had little or no effect on gas exchange, on flowering rate or maturation uniformity – 66% ripe cherries –, and on coffee bean yield and classification of both cultivars. The effect of the different treatments on the water status of the flower buds does not overcome the effects of the blossom rain, which was determinant for their opening.