光强对烟草幼苗形态和生理指标的影响

通过白纱布遮荫模拟不同光生境条件(透光率分别为100%、68.2%、35.4%和16.7%),研究了光强因子对烟草幼苗形态和生理指标的影响.结果表明:随相对光强的减弱,幼苗高度增加,茎粗、干鲜比、叶片厚度和单位叶面积质量均呈降低趋势,幼苗干物质积累减少,但其对叶数的影响不大.弱光条件下,叶片自由水、叶绿素、总氮和蛋白质含量增加,束缚水含量降低,叶绿素a/b值减小,转化酶活性降低;烟草幼苗根系相对不发达,根冠比和根生物量减小,根系活力降低.表明弱光条件不利于培育烟草壮苗,生产中应尽可能改善苗床的光照条件.

Effects of light intensity on morphological and physiological characteristics of tobacco seedlings

Through shading with white gauze to simulate different light habitats(100%,68.2%,35.4% and 16.7% of full sunlight),this paper studied the effects of light intensity on the morphological and physiological characteristics of tobacco seedlings.The results showed that with the decrease of relative light intensity,seedling height increased,while stem circumference,dry weight/fresh weight ratio,leaf thickness,specific leaf weight,and matter accumulation decreased.Less effect of light intensity was observed on the number of seedling leaves.Under weak light condition,the contents of free water,chlorophyll,total nitrogen,and protein in leaves increased,while bound water content,chlorophyll a/b ratio,and invertase activity decreased.The root/shoot ratio,root biomass,and root vitality a/so decreased.All of these suggested that weak light was unfavorable to the cultivation of strong tobacco seedlings,and the light conditions of seedbed should be improved in tobacco production.