Abstract: A stay-green line (RIL-1) and an early-senescence line (RIL-2) were selected from a recombinant inbred line population of 654/LTR108. Five physiological indices were investigated from the leaf samples collected from the seedlings of RIL-1, RIL-2, 654 and LTR108 under drought stress, respectively. The level of proline content increased significantly with the prolonging of drought stress. RIL-2 had the highest level of proline content, followed by LTR108, 654 and RIL-1. The chlorophyll content of 654 and RIL-1 firstly increased and then decreased while RIL-2 and LTR108 exhibited a down-up-down changing pattern. The level of T-AOC activity followed an up-down pattern for all the lines investigated. RIL-2 and LTR108 had the highest level of T-AOC activities at the 3rd day, while RIL-1 and 654 reached the highest level at the 4th day. T-SOD activity had a similar pattern as T-AOC activity. The significant change was observed for RIL-1. Different patterns were observed for the level of the POD activity among 654, RIL-1, RIL-2 and LTR108, up-down pattern for 654, RIL-1 and RIL-2 but down-up-down pattern for LTR108, respectively. The significant change was occurred for the line of 654．

Key words: Sorghum bicolor L. Meonch, seedling, drought resistance, physiological characteristic