Effects of Different Film Uncovering Time on the Fresh Weight of Flue-cured Tobacco Root in Rainy Tobacco Growing Regions

Purpose In order to better grasp the growth regularity of flue-cured tobacco and provide theoretical basis for cultivating tobacco in rainy regions, the effects of different filming styles and film uncovering time on the dynamic parameters of flue-cured tobacco roots was studied.Method Five treatments, including plastic film covered in whole growing period (T1), plastic film covered for 30 days after transplanting (T2) plastic film covered for 40 days after transplanting (T3), plastic film covered for 50 days after transplanting (T4), no plastic film covered (T5), were applied to test the effects of treatments on the refresh weight of tobacco roots in Ninger Town. Based on logistic equation the effects of different removing film time on the whole growth period of flue-cured tobacco root total fresh weight and all levels of root fresh weight the influence of dynamic change were studied as well.Results (1) The correlation coefficients of a logistic equation y=a/(1+be-cx) which was used to simulate the dynamic changes of total tobacco fresh root weight and levels of fresh root weight accumulation were more than 0.98. (2) Fresh root weight accumulation was divided into three characteristic stages:0-50 day, 50-80 day and 80 day to harvest. Root growth dynamic was effected by different film uncovering through changing the ultimate amount, the maximum accumulation time and the average growth rate. (3) The root fresh weight was obviously different at different time between different treatments. The root total fresh weight and root volume fresh weight at all levels were the biggest at the initial flower period, and were the lowest of no covering film treatment at the later growth stage. (4) Covering film over growth stage and the uncovering film at the early stage were in favour of root growth.Conclusion By comparing the root accumulation of five treatments and the growth of root system at all levels, it suggested that the flue-cured tobacco production should be covered film in the whole growth period or uncovered film at the early stage in the rainy tobacco regions.