硅促进水稻种子萌发及缓解幼苗砷毒性的效应研究

通过As~(Ⅲ)胁迫下水稻种子的发芽试验和幼苗毒性试验,研究了外源硅对水稻种子发芽率、幼苗生长的影响及其缓解幼苗砷毒性的效应。外源硅的2种处理方式为种子萌发时添加外源硅(Si1)和采用硅处理液浸种(Si2)。结果表明,发芽时介质中As浓度达到10 mg·L~(-1)时显著抑制水稻种子萌发(P0.05),发芽率仅为80%,但是Si1和Si2处理下发芽率则提高到97%和100%,这说明外源硅可促进砷胁迫下水稻种子萌发;砷浓度≥5 mg·L~(-1)时,Si1和Si2处理均可提高水稻的相对幼苗高度和根耐性指数,提高幅度分别为6.00%~16.8%和57.9%~77.0%、7.10%~23.5%和54.2%~61.2%,并且降低了水稻幼苗砷含量,降低幅度分别为17.8%~21.4%和31.0%~49.1%。这说明外源硅处理可促进砷胁迫下水稻幼苗的生长;不同砷浓度处理与水稻芽长、根长及幼苗干重之间存在"S"型的剂量-效应关系,且外源硅显著提高了相应的EC50,缓解了砷对水稻幼苗生长的毒性。综上所述,砷胁迫下水稻种子萌发时添加外源硅或采用硅处理液浸种均可促进水稻种子萌发和幼苗生长,并降低了幼苗砷累积和缓解砷对水稻幼苗的毒性。

Silicon Treatments Accelerated Rice Seed Germination and Mitigated Arsenic Toxicity to Seedlings

Rice seed germination assay and toxicity test of rice seedlings were conducted to investigate the effects of silicon treatments on seed germination,seedling growth and toxicity of seedling under arsenic stress.There were two silicon treatments in the experiments that silicon was added in the solution with arsenic and rice seeds during germination (Sil) or rice seeds were pretreated with silicon solution for 6 h (Si2).The results showed that germination rate of rice seeds were significantly inhibited at the As concentration of 10 mg·L-1 and only 80％ for the control,while Sil and Si2 treatments increased the germination rate to 97％ and 100％ on the same concentration of arsenic.It is indicated that silicon addition could improve the germination of rice seeds under arsenic stress.When arsenic concentrations were equal to or higher than 5 mg· L-1,Sil and Si2 treatments had higher relative shoot height and root tolerance index of rice than that of control,increasing by 6.00％ ～ 16.8％ and 57.9％ ～ 77.0％,7.10％～23.5％ and 54.2％～61.2％.Moreover,Si addition also reduced arsenic concentrations in rice seedlings,by 17.8％ ～21.4％ and 31.0％ ～49.1％.This suggested that Si could enhance the rice seedlings growth under the arsenic stress.The relationship of dose-effect followed the "s" type between arsenic concentrations and root length,shoot height and dry mass of seedlings.Sil and Si2 treatments increased the ECs0 of rice seedlings,which meant silicon addition during germination or before germination could reduce the toxicity of arsenic when rice seedlings were growing.In conclusion,silicon treatments could increase the germination rate,seedling growth and reduce arsenic concentrations in rice and arsenic toxicity to rice seedlings.