Abstract:

This research explored the physiological and ecological responses and secondary metabolites of Thlaspi arvense （pennycress） under salt stress in order to develop a theoretical foundation for further research on the planting of salt-tolerant plants on saline-alkali soils. Hydroponically cultured pennycress was grown at 5 NaCl concentrations （0， 50， 100， 150， 200 mmol·L^-1） set to simulate a gradient of salt stress intensity. Leaves of pennycress were collected at 1， 5， 10， and 15 days to determine physiological and biochemical indexes， photosynthetic parameters and secondary metabolite levels. It was found that： 1） The activities of superoxide dismutase， peroxidase， and catalase in the leaves of T. arvense showed a pattern of initial increase and then decrease with increase in salt concentration during the period of salt stress.^{2） The enzyme activity was highest at the NaCl concentration of 100 mmol·L-1. 3） Levels of malondialdehyde first increased and then decreased with increase in salt concentration. 4） The contents of soluble sugar and proline in the leaves of T. arvense increased with increase in salt concentration and with the length of exposure to NaCl stress， while soluble protein levels first increased and then decreased with increase in salt concentration. 5） The chlorophyll a， chlorophyll b， total chlorophyll content， chlorophyll fluorescence parameters， net photosynthetic rate and transpiration rates in T. arvense leaves showed a downward trend with increase in salt concentration， and the decline gradually increased. 6） The contents of total flavonoids， total phenols， and sinigrin in the leaves of T. arvense showed a pattern of initial increase and then decreasing with increase in salt concentration. Thus， pennycress has a high tolerance to salt stress and can maintain normal growth in a salt-stress environment of 50-100 mmol·L-1 NaCl concentration. This result provides a theoretical basis for future research on the salt tolerance mechanisms of T. arvense and other natrophilic plants.}

Key words: Thlaspi arvense, salt stress, physiological response, secondary metabolites