P对小麦Cd和As吸收与转运的影响

Effects of P on the Uptake and Transport of Cd and As in Wheat Seedlings

为了探究磷(P)对小麦幼苗镉(Cd)和砷(As)吸收转运生理机制的影响,通过水培试验,以百农207为供试材料,研究了Cd和As胁迫条件下,外源供P和缺P处理对小麦幼苗生长、根系形态、光合参数、抗氧化系统、离子含量和根茎转移系数的影响.结果表明,与缺P处理相比,外源P供应显著增加As胁迫下小麦幼苗叶绿素的含量,促进根系的生长发育,提高了生物量,而对Cd胁迫下小麦幼苗的生长影响不显著.外源P供应时显著增加了Cd胁迫条件下根系的P和Cd含量,降低了地上部的P和Cd含量;同时显著提高了As胁迫条件下地上部的P和As含量以及As向地上部的转移系数.因此,供P与否对小麦幼苗Cd和As毒害的影响表现出明显的差异性;As胁迫时,外源供P提高了As向地上部的转运能力以及根系的CAT活性,降低了As对小麦的毒害,从而促进了小麦幼苗生物量的累积;而在Cd胁迫条件下,P与Cd之间表现出一定的协同效应,外源供P在一定程度上加重了Cd对小麦的毒害效应.

The aim of this study was to explore the effect of P on the physiological mechanism of Cd and As uptake and transport of wheat seedlings.Taking Bainong 207 as the test material,we investigated the effects of exogenous P supply and P deficiency treatment on the growth,root morphology,photosynthetic parameters,antioxidant system,ion content,and rhizome transfer coefficient of wheat seedlings under Cd and As stress using hydroponic experiments.The results showed that compared with that in the P deficiency treatment,the supply of exogenous P significantly increased the chlorophyll content of wheat seedlings under As stress,promoted the growth and development of roots,and increased biomass,whereas there were no significant effects on the growth of wheat seedlings under Cd stress.The contents of P and Cd in the root system under the condition of Cd stress were significantly increased by the supply of exogenous P,and the contents of P and Cd in the aboveground part were reduced.At the same time,the P and As content in the shoot and the transfer coefficient of As from the root to the shoot under As stress were significantly improved.Therefore,the effects of P on the poisoning of wheat Cd and As in this study showed obvious differences.Under As stress,exogenous P supply mainly promoted the growth of wheat seedlings by improving the transport of As from the root to the shoot and the CAT activity in the root system,reducing the poisoning of As in wheat.Under Cd stress,P and Cd showed a certain synergistic effect,and the toxic effect of Cd on wheat was aggravated to a certain extent after the supply of P.