Abstract

The effects of water stress and seed mass on germination, as well as antioxidative enzymes, in Xanthoceras sorbifolia seed were studied. The germination percentage decreased gradually in all seeds with decreasing water potential. The reduction was more significant under -0.6 MPa treatment than under the -0.2 MPa treatment in all seeds. The germination percentage of the big seeds was the highest in all treatments and had the earliest initiated germination compared with those of the medium and small seeds. Lipid peroxidation (malondialdehyde), osmotic substances (free proline), and antioxidative enzymes (peroxidase, superoxide dismutase, and catalase) increased in all seeds with increasing water stress. The values of all parameters indicated that water was a critical factor in X. sorbifolia seed germination, and the big seeds displayed increased tolerance to water stress as measured by germination percentage, osmoregulatory substance, and antioxidant enzymatic activities.

Key words: Germination percentage, PEG 6000, malondialdehyde, free proline, antioxidant enzymes, Xanthoceras sorbifolia.

Abbreviation

 PEG, Polyethylene glycol; EDTA, ethylenediaminetetraacetic acid;MDA, malondialdehyde; CAT, catalase; POD, peroxidase; SOD, superoxide dismutase; PVP, polyvinylpyrrolidone; TCA, trichloroacetic acid; NBT, nitrobluetetrazolium; TBA, thiobarbituric acid.