Effect Of Light Exposure And Manganese-boron On Growth And Physiological-biochemical Characteristics Of Tobacco Seedling

Light, manganese and boron all have regulatory role on plant growth, morphogenesis, carbon and nitrogen metabolism, enzyme activity so on. Through experiments of light quality with intensity and amount of manganese with boron, effect on diffent light, amount of manganese and boron to characteristics of tobacco growth and development, carbon and nitrogen metabolism were studied. The reseach results provide theoretical and experiment basis for culturing strong flue-cured tobacco seedlings. The main study results are as follows:1. Light quality and light intensity greatly effect the growth of tobacco seedlings. The growth of tobacco seedlings were best when light intensity reaches above7200Lux and the proportion of red/blue3:1. The proportion of red/blue3:1can promote chlorophyll synthesis and growth of tobacco seedling, but the proportion of red/blue1:3can promote the growth of root and increase roots activity. Tobacco seedling above ground was unfavorable growth in low light intensity and the high proportion of blue light, while at the low light intensity and the high proportion of red light, tobacco seedling can grow normally above ground. Under night light intensity, total soluble sugar content and enzyme activity of tobacco seedling leaves can be significantly increased by proportion of red/blue3:1, and protein content and nitrate reductase activity of tobacco seeding leaves by proportion red/blue1:3significantly increased. Light quality and light intensity existed highly sensitive regulation on chlorothyll synthesis and carbon and nitrogen metabolism of tobacco seedling.2. From the flue-cured tobacco seed germination to four true leaf growth period, the growth rate of seedling leaves was mainly influenced by temperature and light intensity, while influence of boron and manganese element was small. However, when the tobacco seedlings reach5-leaf-one-heart stage, adding a moderate amount of boron and manganese element obviously promoted growth of tobacco seedlings. Biological indicators among the different boron and manganese processing displayed significant differences in the stem girth, plant height and the root-shoot ratio of tobacco seedlings (P<0.01), especially boron concentration should be controlled within100mg/kg, and manganese concentration200mg/kg. Among the different boron and manganese processing, the chlorophyll, protein, and root activity of tobacco seedlings displayed very significant difference (P<0.01). In the100mg/kg and200mg/kg of Boron and manganese concentration, chlorophyll, protein, and root vigor of tobacco seedlings significantly increased.3. The plastid pigment in tobacco seedlings was mainly affected by the Boron element. Without considering the interaction effect, supplementing of Boron (2-45mg/kg) and manganese (93-120mg/kg), plastid pigment content can be reached highest separately; Considering the interaction effect, combined supplementing of Boron (2mg/kg) and manganese (93mg/kg or120mg/kg) could produce the greatest impact on the synthesis of plastid pigment of tobacco seedlings. Thus, supplying boron and manganese element have obvious role in promoting synthesis of palstid pigment in tobacco seedings leaves.