3. The K c -FAO can lead to significant errors in irrigation scheduling of sugarcane in tropical conditions. The Kc values derived from field soil water balance varied over growing season being 0.18 in the initial growth stage, 1.06 in the mid-season and 0.76 at late stage of sugarcane growth in a tropical region;
4. Both WUE and productivity increased according to increases in water level, and sugarcane ET ranged from 2.7 to 4.2 mm day − 1
.
The yield for irrigated sugarcane ranges from 67.8 to 136.1 t/ha, which is significantly larger than that of rain-fed, 62.6 t/ha.
5. The greatest positive result in yield and WUE was seen in 100% ETo treatment. On the other hand, 25% ET o treatment did not affect yields significantly compared with other treatments,but did result in a significantly increased yield when compared to rain-fed conditions.