Application Technology Research About Effects Of Paclobutrazol On Tobacco Seedlings

In order to nurture tobacco seedlings strongly, different concentrations of paelobutrazol were sprayed on leaves of tobacco seeding at different stages. The major agronomical characteristics were investigated, and some physiological and biochemical characteristics in the leaves of tobacco seedings were determined at different stages.The main results were as follows:1. Spraying the tobacco seedling with different concentrations of paclobutrazol can suppress up growth and elongation of tobacco seedling effectively, that is to say it can reduce height of tobacco plant and leaf area, reduce stem obviously, but can increase stems diameter. Meanwhile, the growth of main root of the seedling and the number of the roots is improved notably. It improve the root cap of seedling obviously and srtong sprout index. The effect becomes more remarkable with the increase of paclobutrazol concentration. The lowest height of stem was found in the treatment sprayed with112mg/L paclobutrazol, which reduced by43.4%as compared with the control.2. The treatments with suitable concentration of paclobutrazol sprayed on leaves of tobacco optimized some physiological and biochemical characteristics in the leaves. It was showed that the paclobutrazol treatments increased obviously the contents of chlorophyll in the leaves, and improved the rates of photosynthesis of the leaves, and increased the activity of the roots and the NR activity. Paclobutrazol treatments increased obviously the contents of chlorophyll by29.6%as compared with the control. Paclobutrazol treatments improved the rates of photosynthesis of the leaves by37.5%as compared with the control. Paclobutrazol treatments increased the activity of the roots by36.5%as compared with the control. Paclobutrazol treatments improved the NR activity by51.4%as compared with the control.3.The treatments with suitable concentration of paclobutrazol sprayed on leaves of tobacco improved SOD activity and POD activity, but decreased the content of MAD in the leaves.Therefore, it could improve drought resistance of the tobacco seedlings. Paclobutrazol treatments increased SOD activity by16.1%as compared with the control. The POD activity of paclobutrazol treatments was1.67times of the control. Paclobutrazol treatments reduced MDA content by60%as compared with the control. 4. The fresh weight of leaf, dry weight of leaf, chlorophyll in the leaves, activity of the root, photosynthesis of the leaves and NR activity were higher in the paclobutrazol treatments than that in the control. The highest fresh weight of leaf was found in the treatment sprayed with56mg/L paclobutrazol, which increased by13.5%as compared with the control. The highest dry weight of leaf was found in the treatment sprayed with56mg/L paclobutrazol, which increased by5.35%as compared with the control. The highest chlorophyll a, chlorophyll b and chlorophyll c were found in the treatment sprayed with56mg/L paclobutrazol, which respectively increased by33.4%,30.9%,32.2%as compared with the control. The highest root activity was found in the treatment sprayed with56mg/L paclobutrazol, which increased by53.11%as compared with the control. The highest rate of net photosynthesis was found in the treatment sprayed with56mg/L paclobutrazol, which increased by28%as compared with the control. The highest NR activity was found in the treatment sprayed with56mg/L paclobutrazol, which increased by75%as compared with the control. The suitable contration of paclobutrazol is56mg/L,5. The fresh weight of leaf, dry weight of leaf, dry weight of leaf, dry weight of root, chlorophyll in the leaves, activity of the root, photosynthesis of the leaves and NR activity were increased maximum in the paclobutrazol treatments on fortieth day than that in the control. They were respectively increased by37.3%,45.5%,18.5%,36.1%,53.4%,30.3%,14.8%and59.4%as compared with the control. The suitable spraying stage is on the fortieth day.6. The fresh weight of leaf, dry weight of leaf, chlorophyll in the leaves, photosynthesis of the leaves and NR activity were increased maximum when we spray the paclobutrazol twice than that in the control. They were respectively increased by24.7%,32.7%,94.9%,51.3%,44.1%, as compared with the control. The suitable spraying times is twice.