Comparison of in-situ root biomass quantification techniques

Climate stressors greatly impact canola production. Studying tolerance of root systems can provide insight about crop response to climate stressors as well as crop resilience to stress events. Conventional methods of quantifying root biomass are destructive, time and labour intensive and are inadequate in capturing the fine roots of canola. The objective of this study is to determine whether root capacitance and root derived carbon methods can be used for the estimation of root biomass of field-grown canola crop. Experimental work took place at the Emile A. Lods Agronomy Research Station in Sainte Anne-de-Bellevue, Quebec. Root biomass measurements were compared using three different methods: 1) manual root washing and weighing, 2) root capacitance (based on a correlation between root biomass and the electrical capacitance of the root system), and 3) root derived carbon method (based on the distribution of 13C in roots of 13CO2 enriched plants). Four nitrogen treatments were used to induce differences in root growth: 50, 100, 150 and 200 kg N ha-1. Root samples were collected at the following critical stages of canola crop development: early flowering, late flowering and pod formation. Relationships between root biomass and above ground biomass are evaluated using robust statistical and crop growth models and detailed analysis will be presented. Evaluation of these methods will provide greater accuracy in quantifying root biomass dynamics in relation to abiotic stressors. This will be important for plant breeders and agronomists in selecting varieties with desirable root systems that tolerate climate stressors, since these considerations are needed to adapt and sustain canola production in Québec to a changing climate.