Grain yield, root growth habit and lodging of eight oilseed rape genotypes in response to a short period of heat stress during flowering

Abstract Increasing temperature due to global climate change is detrimental to both the growth and development of canola (Brassica napus L.) that ultimately leads to a disastrous reduction in productivity. Understanding how these increasing temperatures will impact canola growth in terms of root traits, seed yield and lodging resistance is urgently required to maximize production in the coming decades. A set of eight B. napus genotypes was evaluated under controlled environments with two temperature treatments: 23/17 °C as the optimum (control) and 27.0/24.3 °C mean day/night temperatures as the heat stress. Root traits were assessed using both destructive and non–destructive methods, such as electrical capacitance (EC) and electrical impedance (EI). Simulated root and stem lodging tests were conducted to determine the risk of root lodging and stem lodging, respectively. High temperature stress significantly suppressed root morphological traits, and reduced pod fertility by an average of 28% and seed yield by 34%, along with a reduction in EC (10%) and an increased EI (17%). A significant relationship of EC with root traits (R2=0.53–0.59⁎⁎) and seed yield (R2=0.29*) was also observed. The high temperature treatment reduced the stem bending strength by 7% and stem safety factor by 11%, while did not show a consistent impact on root anchorage strength and root safety factor. The present study suggests that the risk of both yield reductions due to lower fertilization success ratio and crop lodging especially stem lodging increases under short periods of high temperature stress. Furthermore, EC could be applied as a non–destructive technique for evaluating root morphology and genotypic differences in tolerance of canola plants to heat stress.