Effects Of Different Types Of Soil And Regulations On Growth And Distribution Of Tobacco Roots

By field experiment, effects of different types of soil and regulators and agronomy technologies on growth and distribution of tobacco roots were studied systematically from 2000 to 2001, and the results were showed as follow:FirstIy:With tobacco growth and deveopment, tobacco root was deeper and deeper in vertiacl distribution, and wider and wider in horizental distribution. The tendency of vertical distribution of root dry weight(RDW), root length(RL), root surface arae (RSA) and root activity absorption area(RAA) was same in different types of soil . With the deeping of ploughing layer, each index decreased. The horiziontal distribution had the same tendency. The characteristics of root distribution in different types of soil were that RDW on Shajiang black soil was shallow and intensive, and on Cinnamon soil was deep and extensive, and on Alluvial soil was in mediate degree. The characteristics of roots length vertical distribution were that root length of Shajiang black soil distributed shallow and intensive, and that of Cinnamon soil deeply and extensively, and Alluvial soil in the mediate degree. As to the characteristics of roots total surface area and active absorption area vertical distribution, Alluvial soil distributed shallow and intensively, Cinnamon soil deeply and extensively, and the Shajiang black soil in mediate degree; furthermore, the roots surface area and active absorption area of different types of soil were: Shajiang black soil > Alluvial soil> Cinnamon soil. The roots weight and length of Shajiang black soil distributed most narrowly, and of Cinnamon soil most widely, and Alluvial soil in mediate degree. The characteristics of horiziontal distribution of RDW, RL, RSA and RAA were that shajiang black soil was narrow and intensive, Cinnamon soilwre broad and extensive, and Alluvial soil in mediate degree. In harvest stage, the content of nicotine was Cinnamon soil> Shajiang black soil >Alluvial soil; the content of soluable sugar showed : Alluvial soil >Shajiang black soil>Cinnamon soil; the content of K was Cinnamon soil> Shajiang black soil >Alluvial soil; the content of total N was Alluvial soil >Shajiang black soil>Cinnamon soil.The values of sugar/nicotine and N/nictorne of flue tobacco leaf of Cinnamon soil was nearly upto quanliry standard;, but Shajiang black soil had great gap with quality flue tobacco leaf.Activity of SOD and POD was largest on topping period, and MDA content was deepest.54On mature period, the SOD and POD activity of tobacco roots in cinnamon and alluvial soil was higher than that of Shajiang black soil. And that of Shajiang black soil was highest on topping stage.Secondly: Between two regulators, Regulator I used on cinnamon and regulator II used on Shajiang black soil were best. Regulator I can promoted K content , nicotine composition and solution sugar accumulation. Regulator I can activate on cinnamon soil and bacterium on Shajiang black soil and restrain fungi on cinnamon soil, regulator II can activate fungi activity.Thirdly : Different rations element of N took different effect on the development and physiolo gical activity of tobacco roots. N-NO3 had greater effect on root weight, length, total surface area and active absorption area than N-NO3+N-NH4 and N-NH4. In harvest stage, SOD activity showed : N-NO3+N-NH4 > N-NH4>N-NO3. POD activity showed: N-NH4 >N-NO3 + N - NH4 > N-NO3. And the content of MDA showed N-NO3> N-NO3+N-NH4 > N-NH,. The nicotine , K and total N content showed N-NO3> N-NO3+N-NH4 > N-NH4.The characteristics of tobacco root development and distribution of different cultivar were that during growing fast stage, root weight, length, total surface and activity absorption area were showed: multi -leaves cultivar>oligal-leaves cultivar > mid -leaves cultivar. On the 10 days after toping and harvest stage, multi -leaves cultivar >mid-leaves cultivar> oligal -leaves cultivar. In harvest stage, root SOD activity was showed: oligal-leaves cultivar > mid -leaves cultivar >multi -leaves cultivar: POD activity was showe...