Distribution and relationship of phosphorus content in flue-cured tobacco leaf and phosphorus content in soil in Hunan tobacco-growing areas.

The phosphorus contents for 308 flue-cured tobacco leaf samples and 1342 soil samples were determined in Hunan tobacco-growing areas,and their distribution and relationship were analyzed.The results indicated that:(i) The phosphorus content in flue-cured tobacco leaf was suitable in total in Hunan tobacco-growing areas,which ranged from 0.11% to 0.53% with the mean of(0.24±0.07)%;The phosphorus content in 93.83% tobacco samples was located in the range of 0.15% to 0.60%,and the phosphorus content in 41.88% tobacco samples met with the standard(0.20% to 0.28%) of Brazil;the order of the phosphorus content in flue-cured tobacco leaf among different grades was B2FC3FX2F.(ii) Total phosphorus content in soil was low in Hunan tobacco-growing areas,which ranged from 0.18 g·kg-1 to 3.83 g·kg-1,with the mean of(0.78±0.31) g·kg-1.Total phosphorus content for 78.32% soil samples was less than 1.00 g·kg-1.Available phosphorus content in soil was medium,which ranged from 1.00 mg·kg-1 to 92.10 mg·kg-1 with the mean of(19.67±13.63) mg·kg-1.29.66% soil samples were short of available phosphorus(≤10.00 mg·kg-1).The order of available phosphorus content in soil for different soil types was duck feces mud yellow mud field blue mud field sand mud field red yellow mud yellow soil yellow ash soil.(iii) The phosphorus content in flue-cured tobacco leaf had high positive correlation at the 0.01 level with available phosphorus content in soil,and also had high positive correlation at the 0.01 level with soil organic matter,total N,hydrolytic N,available Cu,available Fe,available S and water soluble Cl in soil,but had negative correlation at the 0.05 level with total K,available Mn,available Mo and exchange Mg in soil.Based on the correlation analysis,multiple stepwise regression equations were built between soil nutrients and the phosphorus content in flue-cured tobacco leaf.(iv) When the available phosphorus content in soil was low,the phosphorus content in flue-cured tobacco leaf increased with the increase of soil available phosphorus content.