Abstract:

To investigate the impact of varying concentrations of cadmium on the growth of salt-tolerant rice and enzyme activity in insects, the salt-tolerant rice variety ‘Haihong-12’ was treated with cadmium chloride solution of different concentrations (1.5, 3, 6, 15 mg/kg) for 4, 7, 12, 17, 22 days, respectively, the plant height, root length, chlorophyll content of salt-tolerant rice seedlings and the activities of acetyl cholinesterase and carboxyl esterase of Spodoptera litura larvae fed on treated rice plants were measured under different concentrations and different time of cadmium treatment. The results indicate that the growth of salt-tolerant rice, including plant height and root length, is influenced by both cadmium concentration and time under cadmium stress. The inhibitory effect of a low concentration (1.5, 3 mg/kg) cadmium solution on rice growth was observed intermittently during the treatment period, whereas the inhibitory effect of a high concentration (6, 15 mg/kg) cadmium solution persisted. The chlorophyll content of salt-tolerant rice and the acetyl cholinesterase activity of Spodoptera litura larvae decreased with increasing cadmium concentration, while the carboxyesterase activity of Spodoptera litura larvae increased. The growth of salt-tolerant rice seedlings was impeded by cadmium solution, and the inhibitory effects were intensified with increasing concentrations of cadmium solution. Phytophagous pests exhibited varying trends in detoxification enzyme activities when fed on salt-tolerant rice seedlings treated with cadmium. The results could provide supportive data for optimizing the cultivation conditions of salt-tolerant rice and provide a theoretical basis for further research on the reaction mechanism of heavy metal enrichment in salt-tolerant rice-insect interaction.

Key words: cadmium stress, salt-tolerant rice, growth condition, Spodoptera litura, enzyme activity