Under limited water conditions, the knowledge of crop response to a variable supply of water and crop water use in the different phenological stages are very important parameters to establish strategic irrigation and minimize yield losses. Partitioning of evapotranspiration (ET) in transpiration (T) and soil evaporation is also a key factor for a more efficient use of water in irrigation.
The main goal of the present paper was to determine the duration and crop water use in ET and T in the different phenological stages of sorghum plants under a variable supply of irrigation water. Relations between sorghum yield and water use in both processes were studied. Two simultaneous irrigation experiments with sorghum plants cultivated in pots in a greenhouse were performed. In one experiment ET was obtained by weighing the individual pots. In the other, T was obtained by weighing the pots covered with aluminum foil to avoid soil evaporation.
Water stress affected sorghum water use in both processes during all the phenological phases. Maximum values were obtained in the booth stage. Dry matter production and grain yield were linearly correlated with seasonal ET and T, with higher correlations in the case of T. Water stress also produced a significant reduction in water use efficiency but did not affect transpiration efficiency.