Phytosociology of weeds associated with rice crops in the department of Tolima, Colombia

Phytosociological studies allow for the characterization and descriptive analysis of weed communities in crops. This study aimed to characterize the weed communities associated with weed crops in the "Centro, Meseta, and Norte" zones of the Tolima Department. The study was conducted in 96 commercial lots, in which a 1 ha area was marked off for the sampling. The development stage, density and cover of the weeds were evaluated. The importance value index, the alpha diversity indices of Shannon-Wiener, Simpson and uniformity as well as the similarity indices of Jaccard, Sorensen and Steinhaus were calculated. For the entire department, 42 weed species were identified, with Echinochloa colona being the principal one in all of the zones. In the Centro zone, 27 species were identified; in the Meseta zone, 31 species were identified; and, in the Norte zone, 38 species were identified. The alpha indices demonstrated that the Meseta zone was the most diverse. The Jaccard and Sorensen indices showed dissimilarity in the weed community for all of the comparisons of the zones. The Steinhaus coefficient registered the highest similarity intensity between the Centro and Norte zones