Evaluation of the safety of imazapic for alfalfa crops

This research aims to determine the safety, quality, and weed control effects of imazapic on alfalfa (Medicago sativa). Alfalfa crops that had been planted for 4 years and 10 months were used for the study. The safety level, quality index, and weed control effects of these alfalfa crops were surveyed by spraying different doses of imazapic 10 days after mowing them. Results showed that 7 and 14 days after treatment, treatment with imazapic at the doses of 100.8 and 129.6 g·ha⁻¹ significantly reduced the plant height and fresh weight of the alfalfa (P < 0.05). Inhibitory effects on alfalfa plant height and fresh weight were significantly reduced 28 days after application of 100.8 g·ha⁻¹ of imazapic (P < 0.05). Treatment with imazapic at the doses of 129.6 g·ha⁻¹ still had a significant effect on the plant height, fresh weight, and number of nodules present on the alfalfa plants (P < 0.05). The number of nodules on old alfalfa plants was less than those present on young alfalfa plants. After 28 days, the plant control effect and fresh weight control effect of imazapic at the doses of 86.4, 100.8, and 129.6 g·ha⁻¹ were both higher than 80%. Treatment with imazapic at the doses of 129.6 g·ha⁻¹ significantly affected the yield. The crude protein content was found to have decreased significantly (P < 0.05). The experimental results showed that imazapic had a good control effect on weeds in the dose range of 86.4～100.8 g·ha⁻¹. Use of this dosage had no adverse effect on the growth and quality of alfalfa and significantly increased the yield. It therefore has good promotion value in the context of agricultural production.