Multi-omics analysis of the effects of soil amendment on rapeseed (Brassica napus L.) photosynthesis under drip irrigation with brackish water

Abstract Drip irrigation with brackish water increases the risk of soil salinization while alleviating water shortage in arid areas. In order to alleviate soil salinity stress on crops, polymer soil amendments are increasingly used. But the regulation mechanism of polymer soil amendment composed of polyacrylamide polyvinyl alcohol, and manganese sulfate (PPM) on rapeseed photosynthesis under drip irrigation with different types of brackish water is still unclear. In this field study, PPM was applied to study the responses of rapeseed ( Brassica napus L.) phenotype, photosynthetic physiology, transcriptomics, and metabolomics at the peak flowering stage under drip irrigation with water containing 6 g · L − 1 NaCl (S) and Na 2 CO 3 (A). The results showed that the inhibitory effect of A treatment on rapeseed photosynthesis was greater than that of S treatment, which was reflected in higher Na + content (73.30%) and lower photosynthetic-fluorescence parameters (6.30-61.54%) and antioxidant enzyme activity (53.13–77.10%) of A-treat plants. The application of PPM increased the biomass (63.03–75.91%), photosynthetic parameters (10.55%-34.06%), chlorophyll fluorescence parameters (33.83–62.52%), leaf pigment content (10.30-187.73%), and antioxidant enzyme activity (28.37-198.57%) under S and A treatments. However, the difference is that under S treatment, PPM regulated sulfur metabolism, carbon fixation and carbon metabolism pathways in rapeseed leaves. And it regulated the photosynthesis-, oxidative phosphorylation-, and TCA cycle-related metabolic pathways in rapeseed leaves under A treatment. This study will provide new insights for the application of polymer materials to tackle the salinity stress on crops caused by drip irrigation with brackish water, and solve the difficulty in brackish water utilization.