Regulatory effects of sulfur on oilseed rape (Brassica napus L.) response to selenite

Selenite is a form of selenium (Se) commonly found in Se-excessive soils. To regulate the Se content in plants in high-Se areas, a potted soil experiment was performed on oilseed rape (Brassica napus L.) to evaluate the effects of varied amounts of sulfur (S) on the biomass, accumulation and distribution of Se in B. napus under the conditions of different amounts of Se in the soil. The results showed that the seedlings of B. napus were more sensitive to Se than the mature plants were. The addition of S significantly alleviated the growth inhibition in seedlings and facilitated the growth of mature plants under higher Se (15mgkg(-1)) conditions. S treatment significantly decreased soil pH within the range of 0.22-0.60. An appropriate moderate amount (150mgkg(-1)) of S exerted the strongest inhibition on Se concentration and accumulation in B. napus at the seedling stage, but a higher amount (300mgkg(-1)) of S led to a more significant decrease in the mature plants under higher Se conditions, with the maximum reduction in various parts of B. napus reaching 51.3-60.9% and 42.5-53.4%, respectively. The application of S only affected the uptake of Se, and not the translocation of Se; the accumulation of Se in B. napus follows the sequence of pod approximate to stem > rapeseed > root, and the distribution ratio is approximately 1.00:0.97:0.69:0.49. Overall, the application of S alleviated the inhibitory effect on growth caused by excessive Se by reducing the Se concentration in B. napus and facilitating its growth, suggesting that S treatment is a suitable and highly cost-effective method to regulate the content of Se in B. napus.