中文摘要：

用土培盆栽试验研究了硫酸盐、硒酸盐单一及交互作用对小白菜生长及其硒生物有效性的影响.结果表明,单施硒时,适量硒（≤1.0 mg·kg（-1））能促进小白菜地上部的生长,表现为小白菜株高和地上部干重分别较不施硒对照处理增加了8.4%和22.1%（p〈0.05）,但高剂量硒（≥2.5 mg·kg（-1））却抑制其生长,小白菜株高和地上部干重分别较对照减少了0.4%、14.2%（2.5 mg·kg（-1）Se）和15.8%、50.3%（5.0 mg·kg（-1）Se）.小白菜的根系对硒酸盐的胁迫更为敏感,单施硒处理小白菜根长和地下部干重均低于对照处理,且抑制作用随外源硒添加量的增加而增大,外源硒添加量为1.0、2.5、5.0 mg·kg（-1）处理的小白菜的根长和地下部干重分别较对照下降了20.5%、28.3%、49.4%和29.2%、24.2%、58.5%.施硫能减缓硒对小白菜的胁迫,表现为相同硒剂量下,小白菜根长、地上和地下部干重均随外源硫剂量的增大而增加.另外,施硫处理小白菜叶绿素含量均显著高于相同硒剂量下的无硫处理,过氧化物酶活性却相反.相同硫剂量下,小白菜硒含量随外源硒添加量的增大而显著增大（p〈0.05）,且地上部对硒的吸收和富集能力均显著大于地下部（p〈0.05）.与此不同,施硫显著抑制小白菜对硒的吸收与富集（p〈0.05）,小白菜地上、地下部硒含量和富集系数（BCFSe-shoot、BCFSe-root）均随外源硫剂量的增大而减小.小白菜生物量与其体内硒含量、硒富集系数呈显著负相关.由此可见,硫酸盐是通过抑制硒吸收和富集及调控小白菜自身的生理代谢来减缓硒酸盐对小白菜生长的胁迫.硫酸盐与硒酸盐的相互作用受硫剂量、硒剂量及植株部位的影响.

英文摘要：

Single and combined effects of sulfate and selenate on the growth of pak choi and the selenium bioavailability were investigated with pot experiments. Results showed that applying low amount of Se in soil（ ≤1. 0 mg·kg（-1）） increased shoot height and shoot dry weight by 8. 4% and 22.1%,respectively,compared with the control treatment（ p 0. 05）. In contrast,applying high amount of Se（ ≥2. 5 mg·kg（-1）） decreased shoot height and shoot dry weight by 0. 4% and 14. 2% at 2. 5 mg·kg（-1）Se and 15. 8% and 50. 3% at 5. 0 mg·kg（-1）Se,respectively. Roots of pak choi were more sensitive to Se than shoots,as root growths were inhibited at low Se amount（ 1. 0 mg·kg（-1）） and the inhibitions were more severe with higher Se application rate. Compared with the control treatment,pak choi root length decreased by 20. 5%,28. 3% and 49. 4% and dry weight by 29. 2%,24.2% and 58. 5% when Se application rates were 1. 0,2. 5 and 5. 0 mg·kg（-1）,respectively. Applying sulfate reduced the Se toxic stress of pak choi by increasing root length,shoot height and shoot dry weight,compared with no-sulphate treatments. In addition,sulphate increased chlorophyll content but decreasd peroxidase（ POD） activity of pak choi leaves at the same Se concentration. At the same sulfate concentraction,Se concentraction in pak choiroots and shoots increased with the Se application rate（ p 0. 05）. However,at the same Se concentration,sulfate significantly decreased pak choi Se content with the increasing sulfate application rate（ p 0. 05）,thus reduced Se accumulation in both shoots and roots（ BCFSe-shootand BCFSe-root）. All translocation factors（ TF） were larger than 1. Significant negative correlations were found between biomasses and corresponding Se concentrations or accumulations amount. Therefore,applying sulfate could regulate self-metabolism,inhibit Se uptake,and reduce Se concentration in pak choi,resulting in Se toxicity reduction. In conclusion,sulfate could reduce the Se toxic str