Abstract: The effects of occurrence and development of consecutive drought with different intensities on leaf water content and photosynthetic characteristics of summer maize were studied based on the summer maize drought manipulation experiment from 7leaf stage. The results indicated that the leaf water content decreased linearly during growing season and it was significantly correlated with relative soil moisture (P<0.005), implying that the leaf water content may be used as an index of crop drought. The photosynthetic rate, transpiration rate and stomatal conductance of maize leaf during growing season decreased significantly with the decrease of relative soil moisture. The difference of all these parameters among different water treatments declined with the development of consecutive drought. The water use efficiency showed a rising trend and its difference among different water treatments was small at earlier stage, but enlarged at later stage with the aggravation of consecutive drought. There was a conversion from stomatal limitation to nonstomatal limitation for photosynthesis during growing season, respectively occurring 46, 38, 30, and 35 days after water controlling for W1 to W4 water treatments. The conversion occurrence time was negatively related with drought intensity and consecutive time.

Key words: grain yield, semi-arid region of Loess Plateau, within-row-intercropping, planting density, leaf area index