Effect Of Top Pruning And Growth Regulators On Growth And Potassium Nutrition Of Tobacco

This paper studied the effect of top pruning and plant growth regulators at squaring stage on the growth and development, and the absorption, and accumulation of potassium of tobacco( Nicotiana tabacum L) by methods of water culture and pot trial. The results showed that:1. Top pruning can improve the root system activity of tobacco, the activity of Nitrate reductase and content of chlorphyll in leaf. At the same time, the activity of Nitrate reductase and content of chlorphyll in leaf can also be raised when plenteous potassium was supplied after top pruning.2.Potassium in tobacco has the trend of transferring from leaf to stem and root when tobacco developed to anaphase. The measure of top pruning can promote potassium transfer from root to stem and leaf, increase the potassium content in tobacco leaf. While the treatment of no top pruning, potassium transferred from leaf to stem and root, reduced the potassium content in leaf.3.Nipping different plant growth regulators after top pruning has promotion on plant height, stem circumference, the largest leaf area, node distance, root volume, root fresh weight, and area of the second leaf from top, and different plant growth regulators has different promotions, among them BR has the most prominent effect followed by GA3 and NAA, 2,4-D has the least effect. Plant growth regulators have no effect on tobacco's leaf number significantly. Applying potassium in higher level have no prominent effects on plant height, stem circumference, the largest leaf area, nodes distance, root volume and area of the second leaf from top, but can increase the root fresh weight significantly.4. Nipping different plant growth regulators after top pruning can increase the potassium accumulation of different part in tobacco, promoted potassium transfer from root and stem to leaf, increased the potassium content of middle and top part of leaf in tobacco, improved the quality of tobacco. 5. Nipping different plant growth regulators after top pruning can increase the accumulation of N, P in tobacco, have no prominent effects on the accumulation of Ca, Mg, Mn and Zn. Potassium can increase the accumulation of N, P, Mn and Zn but restrained the accumulation of Ca and Mg.