Assessment of canola crop lodging under elevated temperatures for adaptation to climate change

Global food security and agricultural production is directly affected by global warming. Crops are known to be sensitive to global warming since temperature influences the rate of plant metabolic processes that ultimately determine the biomass accumulation, and grain formation. Therefore, extensive researches have been conducted to project the potential impacts of global warming on agricultural productivity through in situ experimentation, and crop and global climate models. Canola (Brassica napus L.) is one of the world's most important oilseed crops and the most profitable commodity for Canadian farmers. Lodging, the permanent displacement of aboveground portions of the crop from the upright position, which is caused by the external forces induced by wind, storm, rain, or hail, is a common phenomenon in canola production and is the main constraint for increasing canola yields under favorable weather condition. A better understanding of the mechanisms of stem and root lodging in response to high temperature will be helpful to mitigate the most likely form of lodging under increasing temperature stress with global warming. The objectives of this study were to (1) assess the impact of high temperature on stem and root lodging resistance in four different varieties under the controlled growth facility conditions, and (2) determine which kind of lodging (stem or root lodging) is more prevalent under high temperature condition. This knowledge could be useful to plant breeders, farmers, and/or agronomists for canola improvement, and/or selection of cultivars of canola that is more resistant to lodging under increased temperature with global warming.

This study showed that cultivars had significant difference in their overall ability for lodging resistance. The mechanical characteristics and root morphological traits of all four varieties tested were mostly negatively affected by high temperature in a parallel way. High temperature increased the stem lodging resistance in canola plants because it (1) decreased the self-weight moment; and (2) increased the anchorage strength through enhancing stem diameter and dry weight per internode length of basal stem. High temperature decreased the root lodging resistance because it significantly suppressed the lateral root growth, instead of taproot. Root lodging was more prevalent than stem lodging under high temperature conditions. This study implied that enhancing root lodging was advocated as a priority over enhancing stem lodging to increase lodging resistance through breeding selection for a high rigidity root system.