Abstract: Abiotic stresses such as drought and salinity are the major environmental factors hindering plant growth and development. The discharge of municipal sewage sludge has been increased in recent years. The sewage sludge can be treated using alkaline thermal hydrolysis technology. The product alkaline thermal hydrolysate (ATH) contains abundant calcium and organic nitrogen nutrients. To investigate the effects of ATH on the resistance of vegetables against environmental stresses and accomplish the recycling of sewage sludge, Brassica chinensis was subjected to three stress treatments (no stress, drought stress, and salt stress) and three fertilization treatments (no fertilizer, ATH, and urea) in a pot experiment. The results showed that the application of ATH enhanced the yield of B. chinensis by 43.3% compared with urea application without abiotic stress. ATH application reduced nitrate content and increased the contents of soluble sugar, soluble protein and Vc in B. chinensis. Under drought stress and salinity stress, ATH application increased the contents of water-soluble calcium and exchange calcium in the soil and increased the calcium uptake of B. chinensis. ATH promoted the accumulation of proline and decreased the content of malondialdehyde. Furthermore, ATH significantly increased the activity of catalase by 8.6% under drought stress and the activity of peroxidase by 70.4% under salt stress, and thus alleviated the stress caused by adverse environments. The application of ATH to vegetable production can reduce fertilizer input, improve yield, quality and stress resistance of crops, and consequently is a new way for effective, harmless and resource utilization of municipal sewage sludge.

Key words: alkaline thermal hydrolysate of sludge, calcium form, environmental stress, antioxidative enzyme activity, sewage sludge recycling