[Impact of priming on seed germination and seedling growth of Oldenlandia diffusa under drought stress].

Current study was carried out to optimize the priming condition of Oldenlandia diffusa seeds, and improve germination rate and seed vigor of 0. diffusa seeds under drought conditions. Uniform design was used to optimize the concentration and priming time of three priming materials (PEG, KNO3, GA3). Different concentrations of polyethylene glycol (PEG) was used to simulate drought stress. The seedling was cultured in 1/4 Hoagland medium for 30 d. The results showed that seed priming treatment with 366 mg x kg(-1) GA3 for 1h resulted in significant increase in germination rate, germination index, vigor, root length, plant height and biomass of O. diffusa seeds under drought stress (15% PEG), while seed priming with 3.0% KNO3 for 1 h showed little effect on germination and growth of O. diffusa seeds under drought stress. Seed priming treatment with appropriate GA3 concentration and priming time could enhance seed germination and drought resistance of O. diffusa in seedling stage.

[Effects of acidic soil improvement on active-state Cd content in soil and Cd content in Ligusticum chuanxiong].

OBJECTIVE: To explore the method to reduce the Cd content in Ligusticum chuanxiong, and to offer the reference for planting Ligusticum chuanxiong with low Cd content. METHODS: A field experiment was carried out to improve the acidic Cd-contaminated soils by different quicklime application, and the effect of quicklime on the percentage of active-state Cd in soil and Cd content in Ligusticum chuanxiong was examined. RESULTS: Quicklime could reduce the percentage of active-state Cd in soil by increase the acid soil pH value,and as a result, significantly reduce Cd content in Ligusticum chuanxiong. A highly significant negative correlation was found be- tween the Cd content in Ligusticum chuanxiong and quicklime application rate(P =0. 008). Compared with the blank group, Cd content in Ligusticum chuanxiong was reduced by 27. 66%, 24. 87% and 46. 20%, with 750, 1 125 and 1 500 kg/hm2 quicklime application, respectively; while with 1 500 kg/hm2 quicklime application, the soil pH value increased significantly and kept steadily, and the percentage of active-state Cd in soil showed a regular trend which was decreased firstly and increased subsequently. CONCLUSION: Cd content in Ligusticum chuanxiong can be reduced significantly by quicklime application,and the effect of high application of quicklime on Cd content in Ligusticum chuanxiong, soil pH values and percentage of active-state Cd in soil is more effective and steady.