Calcium Peroxide Alleviates the Waterlogging Stress of Rapeseed by Improving the Rhizosphere Oxygen Environment in a Rice-rape Rotation Field

Abstract Purpose Waterlogging stress has a negative influence on agricultural production, particularly for rapeseed yield in a rice-rape rotation field. Calcium peroxide reacts with water to release oxygen, which can serve as an excellent supply. Methods In this field experiment, the conventional rape (Brassica napus L.) variety fengyou958 (FY958) and the early maturing rape variety xiangyou420 (XY420) were used to evaluate the effects of calcium peroxide on waterlogging resistance in a rice-rape rotation field. Waterlogging was imposed from the seedling to flowering stages, and three concentrations of calcium peroxide (0, C1 for the 0.594 kg plot− 1 and C2 for the 0.864 kg plot− 1) were added as basal fertilizer. Results Waterlogging decreased the yield of XY420 and FY958 rapeseed by 74.8% and 87.4%, respectively, while the leaf SPAD values decreased significantly by 17.2% and 21.5%. Treatment with calcium peroxide resulted in an increase of 151%-293% in the yield of rapeseed compared with the waterlogged plants. Moreover, calcium peroxide alleviated the peroxidation of leaves and decreased the activities of catalase and superoxide dismutase by 14.2%-44.4% and 10.9%-19.5%. Compared with the waterlogged plants, the contents of abscisic acid and ethylene in the C2 leaves decreased by 37.3% and 33.4%, while the content of gibberellin increased significantly by 44.9%. The belowground parts of the plants were also significantly affected. The treatments with calcium peroxide reduced the activities of fermentation enzymes in the roots, which significantly reduced the accumulation of fermentation products by 25.0%-57.1% and 16.5%-29.4% for lactate and ethanol, respectively. This reduction was owing to the improved levels of oxygen in the root environment that were released by calcium peroxide. Conclusions The application of a suitable concentration of calcium peroxide enhanced the resistance of rapeseed to waterlogging stress, and this study provides a valid method to prevent damage from flooding in rice-rape rotation fields.