Scholarly Journal of Agricultural Science Vol. 11(3), pp. 42- 45 October, 2021 Available online at http:// www.scholarly-journals.com/SJAS ISSN 2276-7118 © 2021 Scholarly-Journals Full Length Research Paper The Influence of Interactions among Different Weed species in Sokoto, Sudan Savanna Ecological zone, Nigeria Waziri, A.F.* 1 and Usman, M. A. 2 1,2 Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria. Received: 6 October, 2021, Accepted: 21 October, 2021, Published: 28 October, 2021 The study was conducted at the Biological Sciences Garden of Usmanu Danfodiyo University, Sokoto, Sokoto State. Sokoto State is located to the extreme northwest of Nigeria, between latitudes 11°30' N and 13°58' N and longitudes 4°8' E and 6°54' E. It was carried out to assess the competitive ability among four different weed species; Boerhavia diffusa, Cassia tora, Gynandropsis pentaphylla and Tribulus terrestris in various combinations. A total of thirty (30) seeds each of the weed species were planted in the germination containers for the study. B. diffusa was planted in combination with C. tora, G. pentaphylla and T. terrestris. C. tora was planted in combination with T. terrestris and G. pentaphylla; G. pentaphylla was planted in combination with T. terrestris all in three replicates each. The results indicated that B. diffusa had better vegetative growth in all the six combinations. It was able to suppress the growth of the other competitors ( C. tora, G. pentaphylla and T. terrestris). G. pentaphyllahad better growth than C. tora and T. terrestris while C. tora was more competitive than T. terrestris. T. terrestris dried up completely in all the combinations indicating that it has the lowest competitive ability. Therefore, B. diffusa competed better than all the other weed species. Key words: Sudan Savanna; Boerhavia diffusa; Cassia tora; Gynandropsis pentaphylla; Tribulus terrestris; Nigeria. INTRODUCTION Weeds have been defined as plants growing where they are not wanted or as undesirables. In most instances, weeds are plants that take advantage of disturbed sites, having characteristics that allow them to efficiently capture available resources and grow prolifically. Weeds have been described by different authors as colonizers or pioneer species in a disturbed field (Bridges, 1995), as ruderals, which are plants growing in waste places, along roadsides, or in rubbish, or as plants found in highly disturbed but potentially productive environments. Weeds are usually herbs with a characteristic short life span and high seed production. Such plants occupy the earliest stages of succession. Navas (1991) defined a weed as “a plant that forms populations that are able to enter habitats cultivated, markedly disturbed or occupied by *Corresponding author’s e-mail: altine.waziri@gmail.com. man, and potentially depress or displace the resident plant populations which are deliberately cultivated or are of ecological and/or aesthetic interest”. Bridges (1995) suggests that Navas’s definition provides a useful description of a weed that recognizes the ecology and biology of the plant as well as the impact on humans. Therefore, weeds are plants that are equally well adapted to environmental disturbances as our crops. Weeds can thrive under the conditions generated by the agriculture field practices of tillage, irrigation, fertilization, and row spacing that minimize normal growth-limiting stresses of drought, low fertility, limited light, and high pest levels. Competition between weeds and crops generally implies an inhibition of crop growth by weeds. However, more technically, competition is one of several types of interference among species or populations. Interference refers to all types of positive and negative interaction between species. Such interference can involve physical factors such as space, light, moisture, nutrients, and