ABSTRACT

Seasonal distribution of weeds in Hevea brasiliensis (rubber) plantation at Agbarha-Otor, Ughelli North Local Government Area of Delth State, Nigeria, was carried out during the rainy and dry seasons of 2020 using quadrats measuring 10 m x 10 m that were laid at random. Ecological statistics were generated on the diversity indices. Qantification of the weeds revealed the presence of 68 species comprising 63 genera distributed in 29 families. During the dry season the taxa ranged from 12 - 27, individual abundance (179 – 1484), Dominance_D (0.07361 – 0.1890), Simpson index (0.4660 – 0.9264), Shannon Wiener idex (1.099 – 2.832), Evenness index (0.2162 - 0.7383), Brillouin (1.071 – 2.730), Menhinick index (0.3375 – 1.943), Margalef index (1.635 – 4.819), Equitability (0.4423 – 0.9032), Fisher_alpha (1.961– 8.362), Berger-Parker (0.1656 – 0.7177) and Chao-1 was (12.0 – 27.33). In terms of most abundant species, density, relative density and importance index value in dry season in decreasing order were Poaceae > Selaginellaceae > Arecaceae > Melastomataceae > Bromeliaceae > Asteraceae. Diverse families in decreasing order were Poaceae > Asteraceae > Fabaceae = Rubiaceae = Malvaceae > Amaranthaceae = Connaraceae > Acanthaceae =Cyperaceae = Euphorbiaceae = Polypodiaceae = Tiliaceae = Gentianaceae with 7, 6, 5, 5, 5, 3, 3, 2, 2, 2, 2, 2 and 2 species respectively. While in the rainy season taxa ranged from 8 - 29, individuals (175 – 1256), Dominance, Simpson, Shannon Weiner, Evenness, Brillouin, Menhinick, Margalef and Equitability indices were (0.072023 – 0.3566; 0.5096 – 0.9298; 0.8274 – 2.8280; 0.2859 – 0.7201; 0.8071 – 2.739;1.057 – 4.490; 0.3979 – 0.8953; 1.249 – 7.172) respectively. Equitability (0.4182 – 0.866), Fisher_alpha (5.373 – 17.31), Berger-Parker (0.1197 – 0.6944) and Chao-1 were (32 – 62.08) respectively. In terms of most abundant species, density, relative density and abstract importance value index in rainy season, six weed families namely Poaceae, Asteraceae, Fabaceae, Malvaceae, Rubiaceae and Connaraceae were predominant. Similarly, the most diverse families in decreasing order were Poaceae > Asteraceae = Fabaceae > Rubiaceae, = Malvaceae > Connaraceae = Amaranthaceae > Acanthaceae = Cyperaceae = Euphorbiaceae = Gentianaceae = Polypodiaceae = Tiliaceae with 7, 6, 6, 5, 5, 3, 3, 2, 2, 2, 2, 2 and 2 species respectively. The knowledge of weed flora will enable us to know the appropriate method to eliminate them from our agricultural farms to reduce competition with our valuable crops. This study of weed species’ inventory is useful and helpful for rubber producers of this agro-ecological zone while dealing with weed pressure and especially while choosing appropriate weed control methods.