Abstract

This work aimed to determine the competitive ability of two varieties of cassava against six weed species at initial growth stages, in relation to the allocation of dry mass in plants. The trial was conducted as a factorial experiment, with two cassava genotypes (IAC - 12 and Periquita) under competition with six weed species (Euphorbia heterophylla, Bidens pilosa, Cenchrus echinatus, Amaranthus spinosus, Commelina benghalensisand Brachiaria plantaginea), plus eight treatments corresponding to cassava varieties and weed species free from competition. The period of competition between cassava varieties and weeds was 75 days after crop emergence, when shoot and root mass were collected for evaluation of leaf area as well as, dry mass accumulation and distribution along plant organs (roots, leaves and stem). Cassava varieties presented smaller dry mass accumulation when under competition with weed species. Roots were the most affected organ by the competition. On the other hand, partition of dry mass in weeds was barely affected. In general terms, cassava variety Periquita was the most tolerant genotype to the competition and B. plantaginea was the weed species with higher competitive ability.

Key words: Weed species, cassava genotypes, competition, dry matter accumulation.