镉胁迫对‘丽春’桃幼苗镉积累及其根系生长的影响

Effects on the Growth of Root and Cadmium Accumulation in 'Lichun' Peach under Cadmium Stress

以水培‘丽春’桃(Prunuspersica L.Batsch.)幼苗为试材,研究不同浓度镉(1、2、4、8、16和64mg·L-1)和pH5.6的条件下,根的生长长度,生长速率以及树体器官、茎组织、根、叶亚细胞结构中镉积累的变化。结果表明,处理2d后,营养液中镉浓度小于4mg·L-1时根生长速率较对照显著增加(P<0.05),表现为促进生长,随处理天数的增加,刺激生长效果减弱。当营养液中镉浓度超过4mg·L-1,处理时间超过6d时,根生长速率随镉浓度增加而减少,表现为抑制生长。营养液中镉浓度为64mg·L-1时,根系停长。镉在桃树体中的积累量:器官中,根>茎>叶;茎组织中,木质部>韧皮部;根和叶亚细胞中,细胞壁>可溶性部分、细胞核>线粒体;根细胞壁中镉含量显著高于其它亚细胞结构(P<0.05),说明细胞壁在抵御桃树受镉胁迫时起到了关键性作用。

The seedlings of ＇Lichun＇ peach（Prunus persica L.Batsch.）grown in MS nutrient solution under different levels（1,2,4,8,16,64 mg·L^-1）of cadmium at pH 5.6 for 12 d were adopted in the observation.Changes on the growth of roots associating with Cd accumulation in organ,stem tissue and subcellular parts were investigated respectively.The results demonstrated that the rate of root growth increased significantly（P〈0.05）after 2 d of exposure to 4 mg·L^-1 Cd,in addition it diminished along with increasing days under Cd stress.After 6 d of suffering from Cd concentration over 4 mg·L^-1,the growth of root was restrained obviously and the change of vegetal rate was decreased.When the seedlings were disposed subjecting 64 mg·L^-1 Cd,the ability of root growth was completely inhibited.The accumulation of Cd in organ of the seedlings was higher than root,followed by stem and leaf.Furthermore,the content of Cd in xylem was more than that in phloem,the subcellular distribution of Cd was not equilibrated,and the accumulation of Cd in the cell wall of root and leaf was more than that in the soluble materials.The accumulation of Cd in the cell nucleolus of root and leaf was more than that in mitochondria.The content of Cd in the cell wall of root was significantly（P〈0.05）higher than that in other subcellular tissue.It suggested that the cell wall of root plays an important role in alleviating Cd damage due to high Cd concentration.