Abstract: 【Objective】This study was conducted to evaluate the regulating effects of root in different distances to plant center on leaf photosynthetic characteristics and yield, aimed to provide theoretical supports for screening ideal root system architecture to obtain further yield increase. 【Method】Two summer maize cultivars with different root types, Denghai 661 (DH661, deep root type) and Zhengdan 958 (ZD958, shallow root type) were chosen as experimental materials. At the V12 stage, roots were cut vertically at different horizontal distance of 10 cm (T-10), 20 cm (T-20) from maize plant center at 60 cm soil depth, while no roots cutting as control (CK), to investigate the role of root in different soil profiles in regulating yield and leaf photosynthetic characteristics. 【Result】Results shows that, roots of these maize varieties were mainly located within a horizontal area 0-10 cm from the plant center and in this area, 83.13% of total root biomass, 69.55% of total root length, 68.74% of root surface area and 66.44% of root volume were located for DH661, but for the ZD958, percentage of these index were 75.19%, 51.17%, 53.85%, 56.49%, respectively. Compared to ZD958, the root distribution in horizontal of DH 661 was more compact and less impact caused by cutting root in both sides of plant in the distance of 10 cm or 20 cm to plant center. Roots excision made a prominent impact on the photosynthetic characteristics of the two maize varieties leaves, being followed by inhibiting the growth of leaves before anthesis and accelerating senescence after bloom. Root pruning reduced chlorophyll content of two maize varieties and net photosynthetic rate in two years, at tasseling stage (VT), the chlorophyll content of T-20 treatment of DH661 decreased by 4.29% and 6.32%, respectively, the net photosynthetic rate decreased by 5.16% and 4.66%, the reduced rate of T-10 were 6.37% and 6.86%, 6.47% and 8.66%. The reduced photosynthetic rate of T-20 treatment of ZD958 were 6.52% and 9.91%, 6.48% and 9.15%, in T-10 treatments were 15.40% and 15.01%, 11.89% and 15.49%. At the same time, resulted in significant root shoot biomass and grain yield decreased, the index decline was T-10 > T-20, and the deep root type of DH661 was significantly less than the shallow one ZD958. 【Conclusion】Cutting the roots vertically decreased the ability of net photosynthetic of ear leaf, shoot biomass and final yield of the two maize varieties with different root architecture significantly. The range of reduce increases when the cutting position is close to the main stem. The impact of T-20 on DH661 is obviously weaker than that on ZD958. Compare the root architecture, distribution and the root ability of two maize reserved after cutting vertically, the root performance of deep type is more adaptable to greater planting density.

Key words: summer maize, root, root excision, leaf photosynthetic characteristic, yield