水稻对镉和砷的吸收转运规律研究

Studies on the Uptake and Transport Dynamics of Cadmium and Arsenic in Rice

通过盆栽模拟试验,测定水稻关键生育期各器官镉(Cd)、砷(As)含量,探明水稻对Cd、As的吸收转运特征及变化规律。结果表明,Cd在水稻各器官中的含量分布规律为:根>茎>籽粒>叶;As在水稻各器官中的含量分布规律为:根>茎>叶>籽粒。水稻各器官对Cd、As的吸收转运规律差异明显,水稻根、茎和叶Cd含量皆随水稻的生长而逐渐升高,而根、茎和叶As含量皆随水稻生长而逐渐降低。水稻根、茎、叶中Cd、As积累量及积累总量均随着生育时期的推移呈先升后降趋势,但Cd、As积累总量的最大积累峰值不同,Cd在乳熟期,As在分蘖盛期。水稻根系向茎转运Cd的能力高于As,而茎向叶转运Cd的能力小于As。对于镉砷复合污染,采取有效措施控制分蘖盛期之前水稻根系对As的吸收、孕穗期至成熟期水稻根系对Cd的吸收以及分蘖盛期至成熟期水稻各器官间Cd、As的转运分配可同步实现水稻Cd、As含量的有效控制。

The contents of cadmium(Cd) and arsenic(As) in various organs were determined in the critical growing stages of rice to understand the characteristics of uptake and transport and dynamic changes of Cd and As in rice by a simulated pot-cultivation experiment. The results showed that the concentration distribution of Cd was root > stem > grain> leaf and that of As was root > stem > leaf > grain in rice. There existed a significant difference between Cd and As in the uptake and transport rules in various organs of rice. The Cd contents in root, stem and leaf of rice increased gradually with the growth and development of rice while the As contents in root, stem and leaf decreased gradually with the growth and development of rice. In the accumulation in root, stem and leaf and the total accumulation of rice plant, although both Cd and As had the same tendency of first increase and then decrease with the growth and development of rice, they were different in the peak stage. For the total accumulation of rice plant, Cd reached a peak at the milky ripening stage, while As reached a peak at the full tillering stage. The transport ability from root to stem of rice of Cd was higher than that of As, while the transport ability from stem to leaf of Cd was lower than that of As. With respect to the compound pollution of Cd and As, effective measures should be taken to control the uptake of As by rice roots before the full tillering stage, the uptake of Cd by rice roots from the booting to ripening stage, and the transfer and distribution of Cd and As among various organs of rice from the full tillering to ripening stage, so that the contents of Cd and As in rice can be simultaneously controlled.