Abstract:
Sugarcane is a sun-loving grass having C4 photosynthetic path way with efficient water use. Pew studies have analysed productivity in relation to water use efficiency (WUE) of sugarcane. The efficiency of biomass production under water stress is determined by the transpiration efficiency (Tr;) which is the main and appropriate measure of WUE of a crop. WUE is defined as the amount of biomass produced per unit of water used. TE is defined as the amount of biomass produced per unit of water transpired. Therefore, particularly under water limited conditions, both T,, and WUE quantify the efficiency of water use during the biomass production process in the plant. Moreover, considerable variation in these responses to water stress occurs among sugarcane varieties. The T, varies with genotype, management conditions, CO2 concentration and vapour pressure deficit of the growing environment. WUE can be increased by management practices such as higher planting densities and mulching which reduce soil evaporation. WUE of sugarcane ranges from 4.8 to 20.94 g cane kg 1 of water and it should not be constant due to the variation in vapour pressure deficit and stalk dry matter content. High values of WUE are obtained under well watered conditions (Robertson and Muchow, 1994; Inman-Bamber et al., 1999a and Inman-Bamber et al., I 999b). The objective of this study was to evaluate the WUE of commercial sugarcane varieties and thereby to identify sugarcane varieties which are efficient in utilizing soil moisture to grow under different sugarcane growing environment in Sri Lanka.
Materials and:Methodology
A field experiment was conducted at the Sugarcane Research
