ABSTRACT
Competition is the best known form of direct interference of weeds on agricultural crops. However, there is relatively little information on the competition of the weed sudangrass on soybean, which has been common in agricultural areas in the southern of Rio Grande do Sul. The objective of this study was to evaluate the competition between sudangrass and soybeans using replacement series experiments. The experiment was carried out in a greenhouse in a completely randomized design with four replications. The treatments consisted of soybean and sudangrass associations. The experimental units were 8-L plastic pots, in the proportions 0: 8, 2: 6, 4: 4, 6: 2, 8: 0, corresponding to 0, 25, 50, 75 and 100% of the crop and weed respectively. Shoot, root and total dry matter and plant height were analyzed through diagrams applied to replacement series and competitive indices. Soybean showed competitive superiority in coexistence with sudangrass in relation to shoot, root and total dry matter. The intraspecific competition was more significant for the crop and inter-specific competition was more important for the weed.
Keywords:
Sorghum sudanense (Piper) Stapf; Glycine max (L.) Merr; competition; weed
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) RY of competitor and (
) TRY. Dashed lines represent the hypothetical relative yields when there is no interference of one species over another. Relative Yield (RY) and total relative yield (TRY) for shoot dry matter (a) and root dry matter (b) of soybean and Sorghum sudanense, as a function of the plant proportion.
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) TRY. Dashed lines represent the hypothetical relative yields when there is no interference of one species over another. Relative Yield (YR) and Total Relative Yield (TRY) for total dry matter (root + shoot) (a) and height (b) of soybean and Sorghum sudanense, as a function of the plant proportion.
