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 (s) 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.
Key words: Chlorophyll fluorescence, net-photosynthetic rate, pigment, water oxidation, water deficit stress.
PEG, Polyethylene glycol; Pn, net photosynthetic rate; RH,relative humidity; PPFD, photosynthetic photon flux density; Chla, chlorophyll a;Chlb, chlorophyll b; TC, total chlorophyll; Cx+c, total carotenoid; Fv, variable fluorescence yield; PSII, photosystem II; Fv/Fm, variable to maximum fluorescence;NPQ, non-photochemical quenching; Cin, carbon IV oxide inside; Cout, carbon IV oxide outside; SH, shoot height; RL, root length; LA, leaf area; FW, fresh weight;DW, dry weight; Ys, osmotic potentials; Fv/Fm, maximum quantum yield of photosystem II; FPSII, photon yield of photosystem II; qP, quantum efficiency of photosystem II; NPQ, non photochemical quenching.
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