Study On The Variation And Distribution Of Cl～-in Soil And Tobacco Leaves And KCl Amount Applied For South Anhui Tobacco Area

For the understanding of the kinetic variation and distribution of Cl in tobacco area soil of upland yellow-red earth in South Anhui ,soil samples were collected in 4 times of tobacco growth :early winter of 2002,before transplanting in next year, beginning midway, and leaf collecting .Soil sample of each layer (0 ~ 20, 20 ~ 40 40 ~ 60and 60 ~ 80cm depth) was a 5-spot mixture. Result showed that, in 0 ~ 20cm layer, Cl amount was 6.83 ~ 6.79mg/kg at the end of leaf collecting ,very close among treatments, and obviously lower than that of the original value 9.85 mg/kg, which seams to mean that there is no relation between the residual and applied amount of Cl;in 20 ~ 40cm layer, Cl amount tended to increase from the treatment of CK to the treatment of 6.0C1 kg/mu as was observed in the 3 leaf collecting times. The recover of Cl content in all treatment at the end of leaf collecting illustrated that the Cl amount of accumulation in 20 ~ 40cm layer increased with the increase of Cl application level ;in 40 ~ 6 0cm and 60 ~ 80cm layers, Cl amount in all treatments of 3 leaf collecting times showed a general decrease as compared to the original values, even though there was a slight improvement in the minday time of leaf collecting. At the end of leaf collecting, the Cl content in 60 ~ 80cm layer showed not much difference among treatments. It was illustrated that, in upland yellow-red earth of South Anhui, without fertilization would cause a deficit of 0.474kg/mu of Cl,and a run off 0.7327kg/mu brought about an average of 0.7327kg/mu loss each year. Though the run off increased with the increase of Cl application , the deficit of soil Cl reduced.The amount of dry matter accumulation apparently increased along with growth ,the amount was highest in leaves ,lowest in root. No significant variation of the amount was found among treatments . while the accumulation of Clamount was highest in stems, lowest in roots.however ,Clamount in the 3 organs kept decreasing from 0 to 75th day after transplanting ,then turned to rise thereafter presenting a linear correlation between leaf Clcontent and days ,and between stem Cl content and days s well in the ease of 60 and 75days after transplanting .it was also observed that Cl content showed a tendency of stem Cl>leaf Cl>root Cl and tendency of leaf leaf Cl>stem Cl >root Clbefore and after 81.4th day,respectively.Plot and pot experiment indicated that, KCl level basically showed no influence on biomass accumulation but had a second order correlation with leaf Cl content .And in the same treatment in plot experiment leaf blade Cl content was upper>middle>lower, The Cl accumulation rate was different with both leaf position and treatment. Content of Cl of upper leaves was about 5 times that of the lower of in lowest Cl level (1.5kgClkg/mu),but the trend tended to be the opposite in high Cl level ,explaining that the high Cl application seemed mainly to enrich the Cl content in middle and lower leaves .Yet ,the fact was variable in pot experiment. The stem Cl content increased with KCl level and higher than that in the other 2 organs, though not as significant.In accordance with the curve from the relation between leaf Cl and KCl level ,the safe and acceptable rate of KCl instead of K2SO4 application to upland yellow-red earth of tobacco area in South Anhui would be suggested as 3.874-5.5lOKg per mu per year ,but the use of KCl should be very careful in the area ,and ,the recommendation would be 3.874 kg of KCl yearly for each mu, especioully when the year rainfall is lower than usual.