Presently, little is know of the response of sweet potato to different water irrigation amounts. Thus, the purpose of this study was to investigate the effects of different water irrigation amounts on growth and yields of sweet potato. A split plot in randomized complete block design with three replications was used. Six sweet potato cultivars such as Thorpheug, Kai, China, Japan, Pichit 101 and Pichit 1665 were as main plot and sub plot were 4 irrigation regimes based on the ratios of irrigation amount (IW) to cumulative evaporation (E) (i.e., 0.3, 0.5, 0.7 and 1.0). The results disclosed that China cultivar gave the highest growth, total dry weight and root dry weight yield followed by Japan, Kai, Pichit 101, Pichit 1665 and Thorpheug, respectively. Total dry weight and yield significantly increased with increasing the amounts of irrigation from IW/E 0.3 to IW/E 1.0. The lower water regimes increased leaf temperature whereas transpiration rate and total conductance were reduced. However, we were not found the interaction between sweet potato cultivars and water irrigations.
