Comparison of Density and Morphology of Leaf Glandular Trichome at Different Growth Stages of Nicotiana tabacum L

The morphology and density of leaf glandular trichome of six cultivars of Nicotiana tabacum L.at different growth stages and different leaf positions were compared.The results indicated that the glandular trichome observed belonged to 3 types including long stalk,short stalk and headless glandular trichomes,the long stalk glandular trichome was in the majority throughout all growth stages.Starting from budding stage,the head of some long stalk glandular trichomes faded and dropped and turned into headless glandular trichomes.Starting from transplanting stage,in some of the tested cultivars,the density of glandular trichome increased gradually,reached the highest level at budding stage,and then decreased obviously at mature stage.The density of glandular trichome on top surface of tobacco leaf was higher than that on the bottom surface, however there was no obvious density difference between leaf tip,leaf blade,and leaf base.