Abstract:In order to understand the effect of paclobutrazol on growth and physiology characters of sorghum (Sorghum bicolor), the variety ‘Nongdahong 1’ was sprayed different concentration paclobutrazol solution at jointing stage, the growth and physiological indexes were studied. The results showed that compared with the control, the plant height and basal internode length of sorghum decreased after sprayed paclobutrazol, and the stem diameter and ear grain weight increased. Therefore, paclobutrazol treatments could improve the lodging resistance of sorghum. Meanwhile, the chlorophyll content and net photosynthetic rate of leaves increased as well as the antioxidant enzyme activities, and the MDA content reduced. Therefore, spraying paclobutrazol could improve lodging resistance, delay leaf senescence and increase yield of sorghum. In the field production, spraying 450-600 mg/L at jointing stage was more effective.