Large scale phenotyping on the effect of heat and cold stress on Brassica napus during floral development

As a result of climate change temperature extremes are being frequently experienced, which are endangering agricultural production. Oilseed rape (Brassica napus L.; OSR) is an important cool-season oil crop grown worldwide; however, extremes of cold and heat are major threats to production that cause considerable yield losses especially at the flowering developmental stage. The aim of this study was to evaluate the physiological performance of diverse oilseed rape genotypes during reproduction under cold and heat stress. 94 diverse genotypes with variable characteristics and temperature tolerances were treated for 3 days under cold (6/4 °C) and heat (35/23 °C) stress, and yield traits were analysed. Phenotypic analysis of these rapeseed genotypes revealed the impact of cold/heat stress on flowering periods, with cold stress having a minimal, non-significant negative effect on final yield. Heat stress reduced seed yield by 1.3 fold (P = 0.0009), with a significant effect on numerous parameters collected from the main raceme including, seed weight, number, and seed pod fertility. We have identified 28 genotypes that appear tolerant to heat stress, with 5 maintaining high yield that could be used for breeding of heat-tolerant lines for future climate changes.