Composition and Distribution of Aquatic Weeds in some Minor Canals, Gezira Scheme, Sudan (2018)

Abstract

Excessive growth of aquatic weeds in irrigation systems is a worldwide problem. In Sudan, many irrigation schemes have been greatly affected by aquatic weeds such as Gezira scheme. The objective of the study was to evaluate the community composition and distribution of aquatic weeds in some minor canals in the Gezira scheme in 2018. The study area covered six minor canals at Centre Group at Gezira Scheme. Each minor canal was divided into three sections; head, middle and tail (18 sampling sites). The sites were surveyed once in every month for a period of three months during summer and winter seasons. The community composition of aquatic weeds was detected by visual observation, whereas the distribution of aquatic weeds was determined by calculation of percentage of relative frequency. Data were subjected to descriptive analysis and to analysis of variance. The results indicated that the community composition in the six minor canals consists of four groups of aquatic weeds as follows; floating, emergent, submergent and bank aquatic weeds and consisted of 12 species belonging to nine families. Results showed considerable differences in distribution throughout the year. The most dominant species within the groups were; Vossia cuspidata (33% - 41%) within the group of floating weeds, Cyperus alopecuroides (87% - 55%) within the group of emergent weeds and Cynodon dactylon (75% - 83%) within the group of bank aquatic weeds during both summer and winter seasons. Submergent weeds present only in winter season in one species Najas pectinata. Also, results of relative frequency within all aquatic species showed that Vossia cuspidata and Cynodon dactylon were the most dominant species. These finding gives many insights about the problems of aquatic weeds in minor canals and would be useful in the management and control of aquatic weeds.