不同轮作制度对定西地区农田杂草群落的影响
Effects of different rotation on farmland weed community in Dingxi

为探讨不同轮作制度对定西地区农田杂草群落的影响，采用倒置“W”九点取样法，调查了定西地区7种不同轮作制度下田间杂草的种类、数量、地上生物量等。在试验田发现11个科共15种杂草；从杂草发生密度、地上生物量上看，苦苣菜、藜是农田优势杂草，防除的目的杂草；不同轮作田的杂草群落由优势杂草组成；从不同轮作田杂草群落的物种多样性来看，马铃薯胡麻轮作>马铃薯小麦轮作>胡麻小麦轮作>胡麻连作>小麦胡麻轮作>小麦马铃薯轮作>胡麻马铃薯轮作；对不同轮作田杂草群落进行聚类，可分为四类。通过对不同轮作田中杂草的密度、地上生物量和综合优势度比的综合分析，可以看出胡麻连作、小麦胡麻轮作、马铃薯胡麻轮作、小麦马铃薯轮作中杂草的危害性较大。马铃薯小麦轮作、胡麻小麦轮作和胡麻马铃薯轮作对杂草有一定的控制作用。
To explore effects of different rotation on farmland weed community in Dingxi, a survey was conducted by the method of inverted W-sampling to determine species, quantity and aboveground biomass of weeds in different rotation fields.There were 15 weed species of 11 families in different rotation fields. According to the weed density and aboveground biomass, the predominant species were Sonchusoleraceus L. and Chenopodium album. The species diversity index rank in different rotation fields was potato-flax rotation, potato-wheat rotation, flax-wheat rotation, continuous flax, wheat-flax rotation, wheat-potato rotation, flax-potato rotationin sequence. The different weed community clustered four groups. Based on the density, aboveground biomass and summed dominance ratio of weed in different rotation field, the damage of weeds was greater in continuous flax field, wheat-flax rotation field, potato-flax rotation field, wheat-potato rotation field. The potato-wheat rotation, flax-wheat rotation and flax-potato rotation showed certain control ability in the type and quantity of weeds.