Photosynthesis and water relations of peach palms (Bactris gasipaes Kunth) under soil water deficit Maria Luiza Sant’Anna Tucci . Eduardo Caruso Machado . Vale ´ria Aparecida Modolo . Norma de Magalha ˜es Erismann Received: 24 October 2017 / Accepted: 19 February 2018 Ó Brazilian Society of Plant Physiology 2018 Abstract The Amazonian peach palm is presently the main species of heart-of- palm producer in many Brazilian regions. Here we evaluated the effects of soil water deficit and rewatering on leaf water potential (w leaf ), gas exchange and chlorophyll fluorescence emission in peach palms. Plants were grown in 80 L-plastic pots under greenhouse conditions. Water deficit was imposed by water withdrawing for 13 days, when irrigation was re-established for 8 days more. w leaf was measured at 5:30 a.m. and 1:30 p.m. Gas exchange measurements were performed at 8:00 a.m. and at 2:00 p.m., after chlorophyll a fluo- rescence evaluations. The minimum w leaf value observed at predawn was - 1.6 MPa, when net CO 2 assimilation (P N ) was zero on the 13th day of water deficit, thus showing mesophytes characteristics. The sharp P N decrease of 94%, 6 days after the beginning of treatments, demonstrated the drastic effect of the soil water deficit. After rewatering, a rapid recuper- ation of w leaf was observed, whereas P N , transpiration rate (E) and stomatal conductance (g s ) recovered more slowly, reaching values exhibited by the con- trol plants only 7 days after rewatering. The lower maximal quantum yield of photosystem II (PSII) (F V / F M ) values in the midday for plants under water deficit indicated dynamic photoinhibition of PS II to exces- sive PPFD. These results suggest a drought toler- ance of peach palm plants, showing stomatal control of water losses and P N limitation, whereas the photosynthetic apparatus was maintained by photo- protection processes. Keywords Heart-of-palm Á Gas exchange Á Stomatal conductance Á Water potential 1 Introduction The peach palm native to Amazonian is presently the main species of heart-of- palm producer in many Brazilian regions. According to data from the Brazil- ian Institute of Statistics and Geography (IBGE) (2016), Sa ˜o Paulo State (SP) stands out as one of the main Brazilian heart-of-palm producers. About 80% of the production is concentrated in the region named Vale do Ribeira-SP (LUPA 2008). Due to the tradition in heart-of-palm production and mainly to the climatic conditions (rainfall of 1600 mm year -1 , with regular rainfall distribution throughout the year) this region presents ideal characteristics for rain- M. L. Sant’AnnaTucci Á V. A. Modolo Center for Research and Development in Horticulture, Instituto Agrono ˆmico (IAC), Caixa postal 28, Campinas, SP 13012-970, Brazil E. C. Machado Á N. de Magalha ˜es Erismann (&) Laboratory of Plant Physiology ‘‘Coaracy M. Franco’’, Center for Research and Development in Ecophysiology and Biophysics, Instituto Agrono ˆmico (IAC), Caixa postal 28, Campinas, SP 13012-970, Brazil e-mail: normaeri@iac.sp.gov.br 123 Theor. Exp. Plant Physiol. https://doi.org/10.1007/s40626-018-0099-0