Genetic and environmental effects on the occurrence of speltoids in winter wheat cultivars

The occurrence of speltoid off‐types during seed multiplication is one of the major causes for rejection of a wheat cultivar candidate due to phenotypic inhomogeneity. These aberrant plants express an atypical spear‐shaped spike with tenacious glumes. To analyse the frequency of speltoids under field conditions, field trials were conducted at three locations and two sowing times over 2 years based on speltoid off‐type spikes derived from 14 different wheat genotypes. One hundred single ear progeny were developed from the normal and speltoid progeny plants in 2007. A mean frequency of 21.1% and 36.6% speltoid off‐types in plots from normal and speltoid lines was observed, respectively. Plots sown late in the season displayed on average 5.3% less speltoid off‐types, in particular when both sowing times were far apart. Field trials from 2010 revealed 7.9% more aberrant plants compared with 2011. The percentage of speltoids within the field plots ranged from 0.2% to 83.7%, which indicates a large effect of the respective genotype. Finally, strategies to reduce the number of speltoid off‐types are discussed.