Cd胁迫下黄菖蒲幼苗根系生长与Cd积累的研究

采用水培法研究了Cd胁迫对黄菖蒲（Iris pseudacorus L．）幼苗根系生长和Cd含量的影响，用透射电镜观察了Cd胁迫对根尖细胞亚显微结构的影响并确定了Cd沉积部位。结果表明，10mg·L^-1 Cd处理对黄菖蒲幼苗根系的生长有一定促进作用，根毛数量及不定根上侧根的数量、密度和长度均高于对照；Cd浓度高于25mg·L^-1时，根系的生长发育受到抑制，上述指标均显著低于对照。用10～40mg·L^-1 Cd处理后，黄菖蒲幼苗不定根上侧根中的Cd含量均显著高于未长侧根的不定根和去掉侧根的不定根（P〈0．05），说明不定根上的侧根对Cd沉积有重要作用。100mg·L^-1 Cd处理能导致根尖细胞质浓缩、质壁分离和液泡变大，且大量Cd颗粒沉积在细胞壁上和细胞间隙中，表明细胞壁和细胞间隙对Cd的沉积作用可能是黄菖蒲幼苗耐Cd胁迫的重要机理之一。

Study on growth and Cd accumulation of root system of Iris pseudacorus seedling under Cd stress

The growth situation and Cd content of root system of Iris pseudacorus L. seedling under Cd stress were studied by water culture method. And the effect of Cd stress on cell ultrastructure of root tip was observed and the depositing position of Cd particles was determined using TEM. The results show that the 10 mg~ L-~ Cd stress has a certain promotion function to development and growth of root system of I. pseudacorus seedling, and the growth indexes including the number of root hair and the number, density and length of lateral root on adventitious root are all higher than those of the control. If the Cd concentration is above 25 mg · L^-1, the growth and development of root system are inhibited, and the above-mentioned growth indexes are all lower than those of the control. The Cd content in lateral root on adventitious root is obviously higher than that in adventitious root without lateral root or cut off lateral root （P 〈0.05） with 10 -40 mg · L^-1 Cd stress, which indicates the lateral root may play an important role in Cd depositing. After treated by 100 mg · L^-1 Cd, the concentrating cytoplasm, plasmolysis and largen vacuole are observed in root tip cell and a lot of Cd particles deposit on cell wall and in intercellular space. It is concluded that the deposition of cell wall and intercellular space to Cd in root system may be an important factor of I. pseudacorus seedling＇ s tolerance to Cd.