| Genetic yield improvement in maize during the past 7 decades has been associated with increased stress tolerance that has resulted in enhanced yield stability and in the capacity of plants to sustain high leaf photosynthetic rates during the grain-filling period. The objective of this study was to examine possible relationships between the response of leaf carbon exchange rate (CER) during the grain-filling period to low-night temperature and grain-yield stability by identifying quantitative trait loci (QTLs) in a mapping population. During 2004 and 2005, studies on the effect low night temperature on leaf CER were carried out in a field hydroponic system at the Arlkell Research station and yield trials were established at three locations in Ontario. First, three QTLs relating to leaf photosynthesis and five QTLs for grain yield were detected, however, QTLs for tolerance of leaf CER during the grain-filling period to low night temperature were not associated with grain-yield QTLs. Second, significant genotype x environment interactions were apparent for both leaf CER during the grain-filling period and grain yield in the mapping population. |
