砷胁迫下水磷耦合对不同磷效率水稻根表铁膜及其各部位砷含量的影响

为探索缓解水稻砷毒害的农艺措施,以耐低磷水稻99011和低磷敏感水稻99012为材料,通过土培试验,研究水分、磷用量及其交互作用对不同砷浓度酸性土壤中水稻根表铁膜以及植物体内砷分配的影响。结果表明,节水灌溉(干湿交替)明显减少水稻根表铁膜量,降低铁膜、根系、秸秆、颖壳和精米中的砷含量。与30mg·kg-1P2O5相比,180mg·kg-1P2O5能明显减少两个品种水稻的根表铁膜量以及根系和秸秆中的砷含量;对耐低磷品种铁膜砷含量影响不大,但显著降低磷敏感品种铁膜砷含量;在50mg·kg-1砷处理中增加磷用量对水稻颖壳砷含量影响不大,在100mg·kg-1砷处理时能显著降低颖壳砷含量;增加磷用量可明显增加耐低磷品种的精米砷含量,降低磷敏感品种的精米砷含量。水、磷交互效应主要受水分效应的影响。加砷处理后,相同处理下耐低磷品种的根表铁膜量和铁膜中的砷含量显著高于磷敏感品种,而根系、秸秆、颖壳和精米中的砷含量则相反。研究表明,可以通过节水灌溉,并根据砷污染程度和植物磷营养特性确定适当的磷肥用量,从而减少砷在水稻体内的累积,提高食品安全。

Couple Effect of Water and Phosphorus on Iron Plaque and As Concentration in Different Organs of Different P Efficiency Rices under As-Stress Condition

To explore the agronomic measures for relieving As toxicity to rice, soil culture experiments were conducted to investigate the effect of three potential practical methods, water management regime, phosphorous (P) fertilization and their interaction on iron plaque and As distribution in P-efficient rice cultivar 99011 and P-inefficient rice cultivar 99012 in various As-stress acid soil. Results showed that both rice cultivars had less iron plaque and lower As concentration in iron plaque and all organs of rice (root, shoot, husk and polished grain) under water-saving irrigation conditions than that in submergence treatments regardless of As levels. Compared with 30 mg·kg-1 of P2O5 addition, 180 mg·kg-1 of P2O5 addition significantly reduced the amount of iron plaque on the root surface and the As concentration in the roots and shoots of two rice cultivars. Sufficient P amendments had little effect on the As concentration in the iron plaque of P-efficient rice cultivar 99011 compared with insufficient P supply, while it can reduce the As concentration in the iron plaque of P-inefficient rice cultivar 99012 obviously. Sufficient P addition had little effect on the As concentration in the husk of two rice cultivars at 50 mg·kg-1 of As level, but clearly reduced the As concentration in the husk at 100 mg·kg-1 of As level. As concentration in the polished rice of P-efficient rice cultivar 99011 increased with increasing P level, but P-inefficient rice cultivar 99012 reduced. The interaction of water management and P supply was mainly determined by the effect of water management. In the same As treatment, the P-efficient rice cultivar 99011 had more iron plaque on the root surface, higher As concentration in the iron plaque and lower As concentration in the root, shoot, husk and white rice than that of the P-inefficient rice cultivar 99012. The study demonstrated that water management regime, selection of P-efficient rice cultivars and proper P fertilization according to P efficiency of rice cultivar are effective measures that can be used to reduce As accumulation in rice and improve the food safety.