滤减UV-B辐射对烟叶腺毛发育和密度动态变化的影响

Effects of reduced UV-B radiation on tobacco leaf glandular trichome development and density

以烟草品种"K326"为材料,盆栽种植于自然环境条件下(CK)和覆盖不同厚度透明薄膜,分别滤减25%(T1)、50%(T2)和65%(T3)UV-B辐射的大棚中,在"K326"开花期至工艺成熟后期的4个生育期,通过扫描电镜观察了各处理烟叶腺毛形态和密度动态变化特征,并首次报道了"K326"中存在分枝腺毛。结果表明:上表皮腺毛在开花期、生理成熟期和工艺成熟前期对UV-B辐射敏感,下表皮则在开花期和工艺成熟后期对UV-B辐射敏感;T3处理腺毛密度低且延缓腺毛的发育,T1和T2处理腺毛密度较高,在工艺成熟期出现二次发育现象;各处理烟叶腺毛以长柄腺毛为主,CK、T1、T2下表皮腺毛总密度大于上表皮,而T3上、下表皮差异不大;滤减UV-B辐射有利于烟叶下表皮长柄腺毛发育,而引起腺毛二次发育的腺毛类型依处理和时期而异;适当较高强度的UV-B辐射对烟叶腺毛发育有促进作用,在研究地减弱25%～50%的UV-B辐射强度对烟叶腺毛发育较为合适。

Taking tobacco cultivar K326 as test object,a pot experiment was conducted to study the effects of reduced UV-B radiation on the dynamic changes of the morphology and density of tobacco leaf glandular trichome from flowering to post-technological maturity stage.Four treatments were installed,i.e.,natural UV-B radiation（CK）,and reduced 25%（T1）,50%（T2）,and 65%（T3）of natural UV-B radiation via canopy-covering with different thickness transparent plastic film,and scanning electron microscope was used to observe the dynamic changes.It was first reported that K326 leaf had branched glandular trichome.The glandular trichome on adaxial epidermis was sensitive to UV-B radiation at the stages of flowering,physiological maturity,and pre-technological maturity,while that on abaxial epidermis was sensitive to UV-B radiation at the stages of flowering and post-technological maturity.Treatment T3 caused the lower density of glandular trichome and delayed its development,while treatments T1 and T2 induced the higher density of glandular trichome and its secondary development at technological maturity stage.In all treatments,long stalk glandular trichome was the dominant,and its density on abaxial epidermis was higher than that on adaxial epidermis except in treatment T3,in which,the glandular trichome density on the two epidermises was almost the same.Reduced UV-B radiation was conducive to the development of long stalk glandular trichome on abaxial epidermis.Trichome type,which induced the secondary development,varied with treatments and growth stages.Our results indicated that a certain higher intensity of UV-B radiation played an important role in promoting the development of glandular trichome on tobacco leaf,and in the experimental field,reduced 25%-50% of UV-B radiation was suitable for the development of the glandular trichome.