MORPHO-PHYSIOLOGICAL RESPONSES OF AN ALUMINUM-STRESSED RICE VARIETY `LIANGYOUPEI 9'

This study explored the influence of aluminum (Al) stress on the growth of 'Liangyoupei 9 (LYP9)' rice variety. Seedlings were cultured under treatment with different concentrations of Al (0, 100, 500, and 1000 mu mol; pH4.5) for 7 days and analyzed for their root Al accumulation, dehydrogenase activity, root H2O2 accumulation, antioxidant enzyme activity, and other relevant morphological indices. Results showed no significant differences between the rice seedlings treated with different concentrations of Al and those treated with the control, but the root length and relative root growth of the former decreased. Treatment with 100 mon Al significantly led to the increase of fresh/dry weight and chlorophyll content of the rice seedlings. The increase in fresh weight and dry weight positively correlated with the increase in chlorophyll content. By contrast, treatment with 500 and 1000 mon Al exerted inhibitory effects at different degrees. Hematoxylin staining showed that Al mainly accumulated at the apical meristematic and maturation zones, and its accumulation increased with increasing Al concentration. Treatment with 100 mon Al stress significantly increased the root dehydrogenase activity of the rice seedlings, whereas treatment with 500 and 1000 mon Al significantly decreased this parameter. Diaminobenzidine staining showed that Al stress induced root H2O2 accumulation in the rice seedlings and that the output of H2O2 demonstrated a dose-effect relationship with Al concentration. The activities of root superoxide dismutase(SOD), peroxidase (POD), and catalase (CAT) initially increased and subsequently decreased. However, the activities of these enzymes significantly decreased under 1000 mon Al stress. Treatment with 100 mon Al did not significantly influence the malondialdehyde (MDA) content in the roots, whereas treatment with 500 and 1000 nmol/L Al significantly increased this parameter. These findings show that the LYP9 rice variety has certain resistance to Al stress. However, this resistance is inhibited at Al3+ concentrations exceeding 500 mon, and the inhibitory effect increases along with the concentration.