Abstract:

To investigate the effects of different forms of nitrogen nutrition on the growth of rice seedlings under tetracycline antibiotic stress, a nutrient solution culture method was employed. Under different nitrogen forms ( {\mathrm{NH}}_4^{+}-N and {\mathrm{NO}}_3^{-}-N), various levels of tetracycline stress were applied to study the changes in dry matter accumulation, root-shoot ratio, leaf area, chlorophyll content, and antioxidant enzyme activities in rice. The results showed that different forms of nitrogen nutrition could regulate the impact of tetracycline stress on rice growth. Under low-dose tetracycline stress, {\mathrm{NH}}_4^{+}-N was beneficial for promoting rice growth and increasing dry weight in both aboveground and underground parts. In contrast, under {\mathrm{NO}}_3^{-}-N treatment, the dry weight in both aboveground and underground parts was not significantly affected by tetracycline content. As the tetracycline content increased, the content of chlorophyll a and b decreased under {\mathrm{NO}}_3^{-}-N treatment, while the total nitrogen content in both aboveground and underground parts increased. Under {\mathrm{NH}}_4^{+}-N treatment, the content of chlorophyll a and b and plant nitrogen accumulation did not show significant differences, with the highest total nitrogen content in both aboveground and underground parts observed under low-content tetracycline. As the tetracycline content increased, the POD activity in rice increased under different forms of nitrogen nutrition, while SOD activity showed no significant change under {\mathrm{NH}}_4^{+}-N treatment and even decreased under {\mathrm{NO}}_3^{-}-N treatment. These findings suggest that the stress effects of tetracycline on rice plants can be regulated through different forms of nitrogen nutrition.

Key words: rice, nitrogen forms, tetracycline, dry matter accumulation, chlorophyll