A comparison of root and stem lodging risks among winter wheat cultivars

Plant characters that determine stem and root lodging were measured on 15 winter wheat cultivars at three UK sites between 2000 and 2002. A model of lodging was used to estimate stem failure wind speeds (resistance to stem lodging) and anchorage failure wind speeds (resistance to root lodging). The degree and type of natural lodging was also recorded in the plots and this correlated well with the stem and anchorage failure wind speeds. Only a weak correlation (R-2=0-33) was observed between the stem and anchorage failure wind speeds for the 15 cultivars. This can be explained by the absence of genetic correlation between the plant characters that determine the stem and anchorage strength. There was a significant interaction between type of lodging (stem or root) and cultivar for failure wind speed (P<0.001). This showed that the difference between the resistances for root and stem lodging was not the same for all cultivars. Separate classifications for the stem and root lodging resistance of cultivars are developed that would allow the most appropriate crop management to reduce the risk of both types of lodging. Significant differences were found between cultivars for all lodging-related plant characters (P<0.05). These resulted in the cultivar range of the anchorage failure moment to be 110% of the overall mean. Stem failure moment, shoot and plant base bending moments had ranges of 37-49% of their overall means. Breeders should select for wide, deep root plates and wide stems with a high stem wall failure yield stress for the greatest improvement in lodging resistance.