Differences Of Drought Tolerance Evaluated By Physiological Indices At Different Developmental Stages Under Water Stress In Sorghum (Sorghum Bicolor(L)Moench)

With the increasing scarce water resources, drought has become another limiting factor to agricultural production. Sorghum (Sorghum bicolor(L)Moench), a cereal crop with high photosynthetic efficiency, wide adaptability, drought and saline-alkali tolerance, is a good model for drought resistance of crops and plant genomics study due to its wide adaptation to harsh environment and relatively small genome size.In order to build up an easy and reliable testing and selecting system for drought resistance, sorghum varieties654, LTR108and a recombinant inbred line population consisting of230lines derived from654/LTR108were used for evaluations of different physiological indices under water stress. The main results are as follows:1. Five physiological indices were investigated from the leaf samples collected from the seedlings, pre-anthesis and anthesis of RIL-1, RIL-2,654and LTR108under drought stress, respectively. The level of proline content was increased significantly with the development of water stress and a significant negative correlation was observed between proline content and drought resistance. The chlorophyll content of654and RIL-1showed up-down while RIL-2and LTR108exhibited down-up-down changing pattern in seedlings. In pre-anthesis, the chlorophyll content of Ril-2and654was relatively stable, while Ril-1and LTR108showed down-up changing pattern. The level of chlorophyll content of Ril-1and654was relatively stable, while Ril-2and LTR108exhibited down-up changing pattern under water stress during anthesis. The level of T-AOC activity, T-SOD activity and POD activity exhibited different performance for different genotypes, stress level and the occurrence of drought stress. 2. There were significant differences of seedling root length between the normal inbred line,654, and LTR108. Differences among recombinant inbred lines were quite notable and transgressive segregation was observed.QTL mapping results of the seedling root length in230lines showed that one peak was detected each in LG-1, LG-3, LG-5, and LG-7, respectively, but only the one located on the LG-5had a LOD score greater than2.5.