Phytosociology of weeds in cultivation of two varieties of cassava.
This study has aimed to carry out a phytosociological survey of weeds in different collection periods, in cassava crops of two varieties grown in two consecutive years. The varieties were Pão, of the sweet class, and Racha-terra, of the bitter class. The weeds surveys were performed at 28, 56, 84, 112, 140, 168, 196, 224, 252, 280 and 308 days after planting in the experimental units of each variety. For weeds sampling, a sampler with an area of 0.25 m2 released twice at random in the floor area of the treatments was used. The phytosociological survey quantified 5,708 individuals distributed in 17 families, represented by 32 species, of which 25 were dicotyledonous and seven were monocotyledonous. The most representative families in number of species were Euphorbiaceae and Poaceae, followed by Cyperaceae and Fabaceae. The most important species in the two growing seasons were Axonopus affinis, Mimosa pudica, Spermacoce verticillata and Paspalum multicaule. Other important species of the Poaceae family were Axonopus affinis, Axonopus fissifolius and Homolepis aturensis.