| The jointing stage of summer maize in Northwest China coincides with the prone period of high temperature and drought, and maize is vulnerable to the dual stresses of high temperature and drought. Therefore, it is of great significance to study the response of summer maize growth to double stresses of drought and high temperature at jointing stage for high and stable yield of maize. In this study, a pot experiment combined with artificial simulation of high temperature stress was conducted. Two temperature gradients were set: normal temperature group (T0) and high temperature group (T1), and three water gradients were set at each temperature: suitable water (W0), mild drought (W1) and severe drought (W2). A total of 6 treatments were used to determine the changes of photosynthetic parameters, chlorophyll content, plant height and dry matter quality of maize. The results showed that after jointing stage stress, the net photosynthetic rates of T1W0, T1W1 and T1W2 treatments decreased by 39.78%, 40.13%, 57.13%, and SPAD values decreased by 34.99%, 37.47%, and 43.19%, compared with the control treatment T0W0. At filling stage, compared with T0W0 treatment, the plant height of T1W0, T1W1 and T1W2 treatments decreased by 20.40%, 21.51% and 35.22%. The combined stress of high temperature and drought caused serious and even irreversible effects at later growth stage of maize. At the end of maturity, compared with T0W0 treatment, aboveground biomass of T1W2 treatment decreased by 59.60%, and 100-grain weight decreased by 10.09%. The combined stress of high temperature and drought at jointing stage led to the decrease of photosynthetic rate, plant height, dry matter accumulation and yield. However, compared with T1W2 under combined stress of high temperature and drought, the net photosynthetic rate and SPAD value of T1W0 under suitable water treatment increased significantly. Keeping suitable water (70%~80% FC) to prevent the superposition of high temperature and drought helps to alleviate the damage of high temperature stress on maize. |