Activated carbon utilization to reduce allelopathy that obstructs the continuous cropping of asparagus (Asparagus officinalis L.)

The growth-inhibitory activities of allelopathy in asparagus (Asparagus officinalis L.) was studied using the 'Plant Box Method' of bioassay. By this method we confirmed that asparagus produced allelochemical substances. Then we developed a modified plant box method to examine the relationship between the growth-inhibitory activity and the adsorption of allelochemical substances from asparagus by materials. As a result, a type of activated carbon has the ability to absorb the allelochemical substances and prevent the growth inhibition of lettuce, an assay plant. Furthermore, in a field replanted with asparagus, treatment with activated carbon increased the fresh weights of rhizomes and storage roots, as well as the number of storage roots, the growth amount, and the growth index (GI'), when compared to those of asparagus grown on non-treated plots.