Allelopathic effect of stressing sorghum on weed growth

Abstract

Abstract The effect of stressing sorghum by leaf stripping on the emergence and growth of Amaranthus hybridus was investigated in 2018 at Henderson Research Station in Mazowe, Zimbabwe. The experiment was set up as a randomised complete block design with three treatments replicated 6 times. A control with A. hybridus only, and another with A. hybridus sprayed with atrazine were maintained for comparison. Stripping 2 leaves significantly (P < 0.001) inhibited A. hybridus height, leaf area, and dry weight compared to no stripping. Increasing leaf stripping intensity from 2 to 4 leaves caused an increase in A. hybridus height, leaf area, and dry weight, possibly because intense leaf stripping reduced the number of sorghum leaves available to capture photosynthetically active radiation required for photosynthesis, subsequently reducing the volume of photoassimilates channelled to sorghum roots for allelochemical production. Leaf excision may have created an additional sink that modified assimilate allocation at the expense of roots.