The influence of interspecific interference on the seed production of Stellaria media and Hordeum vulgare (volunteer barley) |
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| Authors: | R C VAN ACKER P J W LUTMAN R J FROUD-WlLLlAMS |
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| Institution: | IACR-Rothamsted, Harpenden, Hens AL5 2JQ. UK.;Department of Agricultural Botany. University of Reading. Earley Gate, Reading, Berks RG6 6AU, UK |
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| Abstract: | The effects of the density and proportion of both volunteer barley ( Hordeum vulgare L.) and Stellaria media (L.) Vill. (common chickweed) on the seed yield of both species was investigated in linseed ( Linum usitatissimum L.) and autumn-sown field bean ( Vicia faba L.). A model was created to estimate these effects. It was a combination of two models. The first was a simple linear model relating weed seed number m2 to weed dry weight m2. The second was an inverse linear model relating weed dry weight per plant to weed density. A very good relationship existed between barley dry weight and number of seeds m2 and between S. media dry weight and number of seed capsules m2. This relationship was relatively consistent between experiments. The inverse linear model provided a good estimation of the relationship between weed density and weed dry weight per plant for both barley and S. media . Model variables, however, differed between experiments. Using the combined model it was estimated that, in the absence of other weed species and at a density of 800 plants m2, S. media would produce between 4000 and 48 000 seeds m2, whereas volunteer barley, at a density of 400 plants m2, would produce between 2000 and 8000 seeds m2. The presence of barley always reduced S. media seed yield and a barley population of 100 plants m2 could reduce S. media seed yield by up to 79%. The presence of S. media reduced barley seed yield in only one of three experiments, in which a S. media density of 800 plants m2 reduced barley seed yield by up to 68%. It was concluded that interspecific weed competition should not be ignored as a factor in models of weed population dynamics |
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