Evaluation of Two Temperature Stress Indices to Estimate Grain Sorghum Yield and Evapotranspiration
2004
Ajayi, Ayodele Ebenezer | Olufayo, Ayorinde A.
This study was performed to examine the relationship between canopy temperature (T c)–based stress indices and grain yield and evapotranspiration (ET) of sorghum [Sorghum bicolor (L.) Moench]. The crop was subjected to 14 differentially irrigated treatments of which two were controls maintained at well-watered and dry conditions during three consecutive years. Soil water content and T c were measured, and relationships between T c–based stress indices [stress degree day (SDD), temperature stress day (TSD), and crop water stressed index (CWSI)] and yield as well as ET were examined. The T c–air temperature (T ₐ) difference varied from −2 to +8°C in the stressed treatments and maintained a negative value for most of the time in the well-watered treatment. The relationship between T c − T ₐ and vapor pressure deficit, commonly referred to as baseline in the determination of CWSI, was examined on function of wind speed and global solar radiation. Although observations showed that T c can be influenced by climatic condition, this study confirmed that it can serve as a useful indicator of water stress in the case of sorghum. High correlation found between T c–based stress indices TSD, SDD, and CWSI and ET as well as grain yield suggest the possibility of using these relationships for predictive purposes.
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