The aim of the present study is to investigate the biochemical, physiological and morphological
responses of oil palm seedlings when exposed to polyethylene glycol (PEG)-induced water deficit. Oil
palm seedlings were photo-autotrophically grown in MS media and subsequently exposed to -0.23
(control), -0.42, -0.98 or -2.15 MPa PEG-induced water deficit. Osmotic potential (Ys) in root and leaf
tissues of oil palm seedlings grown under PEG-induced water deficit was decreased leading to
chlorophyll degradation. Chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (TC), total
carotenoids (Cx+c), maximum quantum yield of photosystem II (PSII) (Fv/Fm) and photon yield of PSII
(FPSII) in the oil palm seedlings under water deficit conditions dropped significantly in comparison to
the control group, leading to a reduction in net-photosynthetic rate (Pn) and growth. A positive
correlation between physiological and growth parameters, including osmotic potential, photosynthetic
pigments and water oxidation in photosystem II and Pn was demonstrated. These data provide the basis
for the establishment of multivariate criteria for water deficit tolerance screening in oil palm breeding
programs.