5种土壤处理用除草剂对紫花苜蓿-根瘤菌共生固氮的影响

温室内测定了5种土壤处理除草剂:咪唑乙烟酸,异恶草酮,乙草胺,仲丁灵和氟乐灵对紫花苜蓿鲜重、干重、结瘤和总含氮量的抑制作用。其中以咪唑乙烟酸和异恶草酮的抑制作用为最强,乙草胺和仲丁灵的抑制作用次之,氟乐灵抑制作用最小。咪唑乙烟酸在用量为33．8a．i．g/hm~2时对紫花苜蓿的鲜重抑制率和干重抑制率分别为67．2%和65．3%,氟乐灵在用量为450a．i．g/hm~2时对紫花苜蓿的鲜重抑制率和干重抑制率分别为33．0%和33．3%;与对照植株的结瘤率和总含氮量分别为90．1%和4．2%相比,咪唑乙烟酸用量为33．8 a．i．g/hm~2处理时,紫花苜蓿结瘤率和含氮量分别为为33．1%和2．3%,氟乐灵为450 a．i．g/hm~2处理时,紫花苜蓿结瘤率和含氮量分别为76．0%和3．1%。

INFLUENCE OF FIVE HERBICIDES ON RHIZOBIUM -ALFALFA SYMBIOTIC NITROGEN - FIXATION

The inhibitory effects of 5 herbicides:imazethapyr,clomazone,acetochlor,butralin and trifluralin on rhizobium-alfalfa symbiotic nitrogen-fixation were studied in greenhouse.The results revealed that:ima- zethapyr and clomazone had the strongest inhibitory effects,trifluralin had the lest inhibitory effects.At the dosage of 33.8 a.i.g/hm~2,imazethapyr reduced respectively fresh weight and dry weight by 67.2% and 65. 3%,trifluralin,at the dosage of 450 a.i.g/hm~2,reduced respectively fresh weight and dry weight by 33.0% and 33.3%;nodulation rate and total nitrogen content of alfalfa without herbicides were respectively 90.1% and 4.2%,at the dosage of 33.8 a.i.g/hm~2,imazethapyr reduced respectively nodulation rate and total nitro- gen content by 33.1% and 2.3%,while trifluralin,at the dosage of 450 a.i.g/hm~2,reduced respectively nodulation rate and total nitrogen content by 76.0% and 3.1%.