Enhancing transpiration efficiency (TE), defined as biomass accumulation per unit water transpired, may be an effective approach to increasing sorghum yield in arid and semi-arid regions under drought conditions. Water use efficiency was compared among 12 sorghum cultivars collected from the ICRISAT Genebank and representing diverse origins. Plants were cultivated in a split plot experimental design using pots with two factors in 5 replications. An irrigation system with two levels: the "well water”, and “water stress” were applied. Plastic bags were used to wrap the pots after the phase of water saturation. Transpiration Efficiency (TE) was used to evaluate the performance of a genotype in water deficit conditions. The parameters such as leaf weight, stem weight and root weight were measured and the data were analyzed using the statistical software tool GenStat version 19. Leaf weight, stem weight and root weight varied significantly between genotypes under well water conditions while under water stress conditions only the stem weight measured was significantly different among the genotypes. Significant differences between genotypes for leaf canopy conductance were found. The leaf canopy conductance was weakly correlated to the stem weight and root weight in both well-watered and water stress conditions.

Roots play a fundamental role in plant growth by supplying water and mineral to the stem and leaves. These underground organs are much less known than the aerial organs mainly due to the difficult access to the root systems in soil. In spite of this, only a few studies were conducted on roots. Given the importance of roots for plant growth, a better understanding of their functioning may help solve some issues such as water stress that can affect the performance of the crops. A total of 100 sorghum cultivars collected in the Sahelian zone of Mali an area receiving an annual rainfall of 200 to 600 mm, were used in a root characterization study. The plant materials were composed of 4 races and 5 intermediates sorghum races. Seeds of the entries were planted directly in PVC tubes of 1m containing soil and arranged in completely randomized design with three replications; in one planting date. Each tube was planted in a dugout ground to 50 cm deep.