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针对青海省麦田施用化学除草剂引起优势杂草与次要杂草种群变化现象,采用定点试验和典型调查方法,对杂草种群变化的主导因子、变化趋势等进行研究。初步结果表明:施用选择性除草荆控制杂草群落中占优势地位的靶子杂草后,对整个杂草群落的变化产生重大影响。非靶子杂草和次要杂草迅速上升,成为新的优势种群,其危害程度不亚于原优势种。(1)当除去田间优势种野燕麦后,当年阔叶杂草株数增加28.1％,鲜重增加80％以上。(2)控制占优势的多种阔叶杂草后,原轻度危害的野燕麦上升迅猛,当年穗数增加98.3％,次年可造成严重危害,发生量较原来增加7.1倍。进而说明野燕麦的竞争力优于阔叶杂草。(3)长期使用2.4—D丁酯除草剂,导致抗、耐药杂草如猪殃殃、鼬瓣花、节裂角茴香、刺儿菜、苣荬菜等的兴起。鉴于上述情况,作者对防治对策进行了探讨。认为应积极采取除草剂混配、轮用、交替施用等措施,以减轻杂草群落长期受到单一的定向选择性压力。
Aiming at the phenomenon of population change of dominant weeds and secondary weeds caused by chemical herbicides application in wheat fields in Qinghai Province, the dominant factors and changing trends of weed population changes were studied by means of fixed-point experiments and typical survey methods. Preliminary results showed that the application of selective herbicides to control weeds in dominant species of target weeds, the entire weed community changes have a significant impact. Non-target weeds and secondary weeds rapidly increased, becoming the new dominant populations, the extent of harm as much as the original dominant species. (1) When the dominant species of wild oats were removed, the number of broad-leaved weeds increased by 28.1% and the fresh weight increased by more than 80%. (2) After the dominant broad-leaved weeds were controlled, wild oatmembers, which had been slightly harmed, increased rapidly in that year. The number of spikes increased by 98.3% in that year, causing serious harm in the following year, with a 7.1-fold increase in occurrence. And then the wild oat’s competitiveness is better than the broad-leaved weeds. (3) The long-term use of 2.4-D butyl herbicide led to the rise of resistant and resistant weeds such as Galium aparine, Mustela flower, Acanthopanax senticosus, Brachiaria spp. In view of the above situation, the author discusses the prevention and control measures. It is suggested that measures such as compounding of herbicides, rotation and alternate application should be taken actively in order to relieve the weed community from being subjected to a single directional selective pressure for a long time.