The resulting decrease in leaf area is one of the mechanisms of moderating water loss from the canopy and excessive drought induced injury to the plant. This however may result in decreases in total dry matter production because of reduction in photo synthetically active leaf area [23] Length and Diameter of Root: Result in Fig. 4. Show that root length and diameter were decreased when cassava plants subjected to severe water stress. There were significant differences among the irrigation treatments. In cassava growth, the importance of root systems in acquiring water has long been recognized. A prolific root system can confer the advantage to support accelerated plant growth during the early crop growth stage and extract water from shallow soil layers that is otherwise easily lost by evaporation [34].