烤烟品种K326和云烟87对镉胁迫的生理响应及抗性差异

Physiological Response and Resistance of K326 and Yunyan87 to Cadmium

水培条件下,研究镉(Cd)胁迫后2个常用烤烟品种(K326和云烟87)对Cd的吸收及Cd在细胞中的分布,比较Cd处理前后烟株的生物质积累、叶绿素含量、根系活力、叶表及根尖微结构的变化。结果表明,外源Cd处理使K326的生物量比对照降低37.7%,云烟87生物量降低76.2%;K326的总叶绿素含量比对照降低64%,云烟87的降低53%;K326根的活跃吸收面积比对照降低33.3%,云烟87的降低13.9%。不加Cd时,2种烟草气孔大小均一,密度相近,Cd处理后,两者的气孔均减小,密度增大。在Cd的影响下,K326品种的细胞直径下降了35%,云烟87的下降不显著。Cd处理使完整饱满的根尖变得皱缩平秃。Cd处理使K326叶表腺毛腺头变小、腺毛变细,尤其腺基部变细更明显;Cd处理使云烟87叶表腺毛发育相对延迟。Cd主要存在于K326和云烟87的根部,分别占总量的82%和89.4%,在叶细胞的5个组分中,以可溶性组分中最高,且K326中Cd的含量高于云烟87。从生物质积累量来看,Cd处理对K326的影响小于对云烟87的影响,两个烟草品种耐受Cd的能力差异较大。

The uptake of cadmium by flue-cured tobacoo K326 and Yunyan87 and its distribution in plant cells were studied by hydroponic culture, with the comparison of biomass accumulation, chlorophyll content, root activity and microstructure changes in various treatments. The results showed that K326 decreased less than Yunyan87 in biomass, while in root activity and chlorophyll content, K326 declined more rapidly than Yunyan87. Without Cd, the size of stomas in K326 and Yunyan87 was homogeneous and the density of stomas appeared similar, whereas under Cd stress, reduced size of stomas and increased density of stomas occurred in both of the two tobacco varieties. Under Cd stress, Root diameter of K326 reduced by 35%, while no evident change was observed in Yunyan87. Cd stress migh result in abnormal root tip, and weak trichome of K326, and retarded development of trichome for Yunyan87. Cd was mainly detected in roots of the two varieties, with greatest distribution in soluble fraction of tobacco leaves. K326 exhibited more total level of Cd than in Yunyan87. Regarding biomass accumulation, Cd stress had less effect on K326 than Yunyan87. In summary, great differences of Cd tolerance exist between the two flue-cured tobacco varieties.