Abstract: To investigate the physiological properties of maize seedlings in enhancing the chilling resistance under exogenous trehalose, a pot experiment was carried out with ‘Xianyu 335’. The effects of 12 mmol·L^-1 exogenous trehalose on root biomass, antioxidant enzyme activities and osmotic adjustment substances of maize seedlings at different chilling temperatures (0, 2, 4, 6 and 8 d) were examined. The results showed that chilling stress significantly inhibited root growth and dry matter accumulation of maize seedlings, increased antioxidant enzyme activity, and destroyed the level of osmotic regulation. In response to trehalose application, root surface area, root length and fresh dry weight of maize seedling significantly increased, activities of SOD, POD and CAT in roots first increased and then decreased, MDA content and relative conductivity in roots significantly reduced. The contents of proline, soluble protein and soluble sugar in the roots were also increased first and then decreased. Compared with the CK+L treatment at the 6th day of chilling treatment, the root surface area, root length and dry weight under the treatment of T+L increased by 18.25%, 4.73%, 2.48% and 21.43%, respectively. The activities of SOD, POD and CAT significantly increased by 17.26%, 23.79% and 30.78%, respectively. The MDA content and relative conductivity significantly decreased by 45.13% and 63.25%, respectively. The contents of proline, soluble protein and soluble sugar in T+L treatment were the highest at the 6th day after chilling stress, being 2.93, 0.51 and 2.58 times higher than that under CK+L treatment, respectively. It is concluded that trehalose can regulate the physiological level of roots of maize seedlings under chilling stress, improve the ability of stress resistance of maize seedlings, and accelerate root growth. Trehalose has a synergistic effect on the physiological regulation of crop growth under low temperature stress. At chilling environment, trehalose can significantly enhance the expression of enzymes in the antioxidant system and the accumulation of osmotic substances.

Key words: net primary productivity, climate change, LPJ-GUESS model, net ecosystem productivity., forest ecosystem