Pytosociological studies on the weed flora of cotton crop in visakhapatnam district, Andhra Pradesh, India

Cotton is one of the most important commercial crops cultivated throughout India. A survey on the weeds growing in cotton crop fields in the 43 mandals, of Visakhapatnam district was carried out to identify the weed flora, species composition, density, frequency and importance value index (IVI). A total of 55 different plant species belonging to 45 genera and 21 families have been recorded in cotton fields in the study area. Among 21 families Asteraceae was the largest weed family representing 10 weed species, while Euphorbiaceae with 7 species reported as the second largest weed family followed by Poaceae (5) and Cyperaceae (4). The results of phytosociological studies revealed that Phyllanthus debilis (3.10) was found to be the most abundant species followed by Chromoleana odorata (3.0) Celosia argentea (2.6) Phyllanthus amarus (2.6) and Cyperus iria (2.58). The Important Value Indiex (IVI) of individual weed species encountered in the cotton crop fields revealed that Chenopodium album (9.44) was the most important species followed by Euphorbia hirta (8.94), Phyllanthus maderaspatensis (8.62) Cleome viscosa (8.03) and Tridax procumbens (8.03) in that order.