咪唑乙烟酸土壤处理对紫花苜蓿及其根瘤生长的影响

采用田间试验的方法，研究了5.0%咪唑乙烟酸水剂的土壤处理对紫花苜蓿(Medicago sativa)及其根瘤生长的影响。结果表明,5.0%咪唑乙烟酸水剂4个施用剂量（0.067 5、0.082 5、0.097 5和0.112 5 kg/hm2）的土壤处理对紫花苜蓿出苗率及生长状况的抑制作用明显。其中剂量0.112 5 kg/hm2咪唑乙烟酸的抑制作用最强，剂量0.082 5和0.097 5 kg/hm2的抑制作用次之，剂量0.067 5 kg/hm2的抑制作用最小。通过施药后3次取样表明，不同剂量咪唑乙烟酸土壤处理后苜蓿根瘤数目、干质量积累增长的抑制效应不同，高剂量条件下苜蓿受到较长时间的抑制作用；中间剂量和低剂量作用下随时间的推移可以解除对根瘤干物质积累的抑制作用，苜蓿根瘤等级状况可以得到恢复或改善。施药后10周，不同剂量咪唑乙烟酸可导致紫花苜蓿植株干质量在0.05水平上差异显著，但植株全氮量差异不显著，范围在2.2~2.6 mg/g。因此，咪唑乙烟酸土壤处理对紫花苜蓿根瘤菌生长的安全用量不应高于0.067 5 kg/hm2。

Influence of imazethapyr soil treatment on growth of alfalfa seedlings and root nodules

A field experiment was conducted to investigate effects of four different applied doses of 5.0% imazethapyr on growth of alfalfa(Medicago sativa) seedlings and root nodules in Heilongjiang.The results indicated that application of imazethapyr at different levels(0.067 5、0.082 5、0.097 5、0.112 5 kg/ha) leaded to the different negative effect on alfalfa emerging and seedling growth.The dosage at 0.112 5 kg/ha had stronger inhibitory effect than those of others,while the effect of 0.067 5 kg/ha was the least.The study also showed that the negative effect on increase of nodule number and their dry weight accumulation with high dosage of imazethapyr lasted longer,while medium and low dosages had shorter inhibiting time and easy resuming from inhibition.There were significant differences(P<0.05) of dry weight of alfalfa seedlings at the different dosages applied after 10 weeks,but the difference of total nitrogen contents was not significant.Therefore,the dose of imazethapyr at 0.067 5 kg/ha might be a safety level on growth of alfalfa seedlings.