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

Abstract

<p>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 <em>Echinochloa colona</em> 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. </p>

Soil Microbiota of Dystric Cambisol in the High Tatra Mountains (Slovakia) after Windthrow

“…In ecology, the similarity index is often used. The similarity of soil micromycocoenoses based on identified fungi was determined according to Sőrensen S S = 2a/(2a + b + c) and Jaccard S J = a/(a + b + c), where a is the number of species in sample a, b is the number of species in sample b, and c is the number of species common in both (a and b) samples [47].…”

Evaluation of chemical and non-chemical weed control practices on weed communities and maize yield in two agroecological zones of Swaziland

“…The nomenclature of plant species followed that of botanical keys supported by regional field identification guides (Lightfoot, 1970;Vernon, 1983). Rank-abundance was used to display species relative abundance data to provide a complete description of the community diversity and simultaneously show both components of species diversity, species number, and evenness under each weed control treatment (Ramírez, 2015). The relative abundance of a species indicates its degree of dominance or subordination in the weed community (that is, the lower the number, the greater the relative abundance of a species in the weed community and the higher its dominance).…”

Confirmation of Multiple Resistant Chloris radiata Population, Harvested in Colombian Rice Fields

“…The most common weeds in rice crops around the world in the last 30 years are species of the Echinochloa genus (E. crus-galli and E. colona mainly) and weedy rice [2]. However, the most common weeds in rice crops in Colombia are Echinochloa colona (barnyardgrass), Oryza sativa (weedy rice), Cyperus iria, Ischaemum rugosum, Eleusine indica and Digitaria bicornis [10][11][12].…”