Water productivity of selected sorghum varieties.
The majority of people living in rural communities rely on rain-fed farming for their agricultural production. Under these conditions, water stress through drought or uneven rainfall distribution is a major limitation to crop production. Sorghum is drought tolerant and has the ability to produce reasonable yields under water limited conditions. The aim of this study was to evaluate crop growth and development under varying water regimes and determine water use of three sorghum varieties (PAN8816, Macia and Ujiba landrace). Two pot trial studies were conducted under controlled environment conditions. The first study evaluated the responses of three varieties (PAN8816, Macia and Ujiba) to water stress imposed at different growth stages [no stress (NS), vegetative stress (VS), reproductive stress (RS) and yield formation stress (YS)]. Thereafter, harvested seeds were subjected to seed quality tests. The second study determined the water productivity of three sorghum varieties (PAN8816, Macia and Ujiba). Results showed that the reproductive and yield formation stages were the most sensitive to stress. Sorghum demonstrated a degree of phenological plasticity in response to water stress imposed at different growth stages. Ujiba performed similar to the hybrid and open–pollinated varieties under all water regimes and better under water limited conditions. Under optimum conditions, PAN 8816 used water more productively compared to Ujiba and Macia. The high water productivity was associated with the high leaf area. Progeny from the NS and VS water regimes showed high germination capacity with the exception of progeny from plants subjected to water stress (RS and YS). It can be concluded that the Ujiba landrace may be recommended for cultivation by farmers in water limited areas because of its ability to produce reasonable yields under water stress. Water stress during reproductive and yield formation stages results in yield losses and poor seed quality in subsequent seed.