高寒区农茬口对当归田杂草群落特征的影响

农田杂草危害是高寒区当归生产的主要限制因子。采用田间调查和统计鉴定相结合的方法,研究了甘南藏族自治州卓尼县培育的马铃薯和油菜茬口当归栽培田杂草群落动态,以当归重茬为对照,旨在揭示茬口特性对当归田杂草消长动态的影响,为筛选适宜栽培当归的农茬口和田间杂草防控提供科学依据。结果表明,在试验茬口当归田共发生杂草15种,隶属9科15属,主要优势种群为锦葵、欧洲千里光、苦苣、繁缕、刺儿菜和甘露子。当归田杂草种类、密度、多样性和生物量因茬口和季节的不同而异,季相消长跃变程度更大,随季节延后杂草多样性下降,优势种杂草利用资源的相似性更高,锦葵和欧洲千里光随当归返青而滋生,随当归生长发育而迅速蔓延,成为占优势的恶性杂草,对当归的危害性最大,导致杂草群落稳定性降低,在当归重茬和马铃薯茬田单生优势度更为突出,优势杂草潜在恶化危害性增大,但在油菜茬田杂草生长量最小,与当归生长竞争势较弱,使当归始终占据优势生态位,说明油菜茬口较利于当归栽培,但根据恶性杂草物候特征及早防除更为关键。

Effects of crop stubble on weed community characteristics in Angelica sinensis fields in an alpine cold region

Weed competition is the main factor limiting Angelica sinensis production in cold alpine areas.Combining field investigation with statistical modelling,the weed community dynamics in cultivated fields of the medicinal plant A.sinensis were studied,and compared with those of potato and rape crops.The work was conducted in Zhuoni county of Gannan Prefecture.The aim was to investigate the effect of crop residue characteristics on weed invasion and population change,to provide a scientific basis for defining agricultural residue management practices suitable for cultivation of medical plants,and for development of weed control protocols.The results showed that 15 weed species from 9 families and 15 genera were important.The dominant weed species were Malva sinensis,Senecio vulgaris,Sonchus oleraceus,Stellaria media,Cirsium setosum and Stachys sieboldi.The species,density,diversity and biomass of the weeds all varied with the residue properties and season.Of the two,the seasonal fluctuation was stronger.The diversity of the weed population diminished with time from planting,resulting in stronger competitive impact of the weeds on the crop through a highly similar usage of resources.The weed species M.sinensis and S.vulgaris were especially competitive and established with spring re-greening and spread during development of the Angelica.This pattern was especially prominent in both second-year Angelica crops and potato residues.However,the total weed biomass was the least in rape crop residue,resulting in weak competitive effect against the medicinal.To summarise,the rape residue is the most suitable for Angelica cultivation but it is also pivotal to control the more competitive weeds.