Canola Lodging Assessment Under Elevated Temperatures for Adaptation to Climate Change.

Lodging is a main cause of yield loss and quality reductions in canola/oilseed rape and other crops. However, there has been little research to date on the mechanisms of crop lodging resistance, especially how this might be affected by higher temperature stress. The objectives of this study were to examine the structural features of canola genotypes in response to high temperature stress, to determine what kind of lodging (stem or root lodging) was more prevalent, and identify corresponding mechanistic traits associated with lodging. The experiment was carried out in controlled growth facilities, with the genotypes tested under normal (23/17°C, CK) and high temperature (27.01/24.3°C) regimes. At maturity, canola stems underwent a three point bending test, while the roots underwent a root lodging test, and the morphological traits were analyzed. The results showed that genotypes differed significantly in their overall ability for lodging resistance, which implied that a wide intraspecific variability existed for genotype selection. High temperature reduced root lodging resistance significantly, as indicated by a dramatic reduction in both anchorage strength and safety factor. These were due to the suppression on lateral root growth, and thereby reduction in root bending resistance, root–soil cone dimension, and its shear strength. In contrast, high temperature showed inconsistent effect on stem lodging resistance, which was evidenced by engineering mechanics theory and anatomical observations. The results indicated that the current canola genotypes are more prone to anchorage failure than stem buckling, and root lodging would become further susceptible under rising temperature with global warming. Present study implies that root lodging should be targeted as the priority to increase lodging resistance through breeding selection for a root system with high rigidity, especially when the crop plants are expected to encounter inevitable high temperature stress.