Abstract:Coastal areas in eastern China have a large amount of reclaimed land and slight saline water resources. In order to exploit the reasonable and sustainable utilization of them, a pot experiment was carried out to investigate the characteristics of soil salinity, photosynthesis parameters, oxidation parameters, antioxidant enzymes activities, growth, yield and water use efficiency of summer maize (Zea mays L.) subjected to three alternate sequences (i.e., BFF: in which maize was irrigated with saline water at the seedling stage and fresh water at other stages;FBF: in which saline water was irrigated at the jointing stage and fresh water at other stages;FFB: in which plants were watered with saline water at the reproductive stage and fresh water at other stages) with three levels (i.e., 1 was 1g/L NaCl;3 was 3g/L NaCl;5 was 5g/L NaCl). The result showed that under the same salinity of saline water irrigation, the descending order of soil salt content distribution in upper layer was FBF,F(xiàn)FB and BFF. Net photosynthetic rate (Pn) and stomatal conductance (Gs) of summer maize leaves under slight saline water irrigation were decreased compared with that under fresh water irrigation throughout the whole growth period (CK). Under the same salinity irrigation, the descending order of Pn and Gs was FFB, BFF and FBF. Intercellular carbon dioxide concentration (Ci) was decreased due to stomatal limitation, but with the increase of irrigation water salinity, non-stomatal limitation caused Ci to increase in 5g/L treatment. FBF5 had a maximum increase of 19.44% at 81d and FFB5 had a minimum increase of 1.38% at 108d. Hydrogen peroxide and malondialdehyde (MDA) in maize leaves under saline irrigation was higher than those under freshwater irrigation. At the same time, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were also increased. However, limitation of the activities of POD and CAT was observed in FBF5 treatment, but it was still higher than those of CK by 37.67% and 13.71%. Compared with CK, alternate irrigation with fresh and slight saline water inhibited the growth and production of maize, resulting in the reduction of plant height, leaf area, growth, yield and water use efficiency. In addition, these adverse effects were more evident in BFF and FBF, because the salt resistance of summer maize was not fully developed and it was more sensitive to salt stress caused by brackish water irrigation. Maize suffered from the most deleterious impact due to saline irrigation during the jointing stage, leading to the most loss of growth and yield. It was confirmed that although maize became more tolerance as crops developing, enhanced crop evapotranspiration also caused more intense salt stress at the jointing stage. Its increasing salt resistance was still insufficient to overcome the corresponding salt stress. In all alternate sequences,the order of water use efficiency (WUE) of summer maize from high to low was FBF,BFF and FFB. As the degree of salinity was increased, the WUE of FBF5 was the lowest, which was decreased by 38.04% compared with that of CK. Based on the analysis of the experimental results, 1g/L and 3g/L salinity water irrigation can be applied at the seedling stage with negligent negative impacts on maize production, and higher salinity irrigation can be used at the reproductive stage, while freshwater irrigation was more appropriate during the jointing stage.