Influence of Alternanthera philoxeroides on the Growth of Garlic and Its Economic Threshold

Alternanthera philoxeroides(Mart.) Griseb.is a noxious exotic weed species.The occurrence and infestation of Alternanthera philoxeroides in garlic fields constitutes a major threat in garlic production.To determine the influence of Alternanthera philoxeroides on the growth of garlic and its economic infestation level,additive series experiment and curve fit were adopted to study the changes of yield characters of garlic under different density of Alternanthera philoxeroides.The results showed that with the interference of Alternanthera philoxeroides,the plant height,bulb number,root number,light penetration rate,yield of garlic bolts and cloves decreased gradually as the weed density increased.The logarithmic regression model was relatively better in describing the relationship between Alternanthera philoxeroides density and yield loss of garlic cloves(y=6.039lnx+0.977,P0.001).When manual weeding was adopted in the control of Alternanthera philoxeroides in garlic fields,the economic infestation level for Alternanthera philoxeroides was 5.21% and the economic threshold was about 4.02 plant per m2.