| Flue-cured tobacco zones of Chongqing mainly include four districts (Qianjiang District, Wanzhou District, Fuling District and Nanchuan) and eight counties (Wulong, Shizhu, Pengshui, Youyang, Fengdu, Wushan, Wuxi and Fengjie).The region has a unique and natural climate, The tobacco with montanic characteristics in the region was preferred for many cigarette companies. In recent years, with the improvement of production management and production technology, the quality of flue-cured tobacco in Chongqing has been significantly improved. However, there were severe production problems of extremely slow growth of tobacco plants and lower accumulation of dry matter in earlier growth stage, resulting in a low yield and poor quality of flued-cured tobacco in Chongqing. Therefore, in Wushan, which was one of major flue-cured tobacco zones in Chongqing, the methods of field trials and laboratory analysis were adopted in this paper, and the regulation of key control techniques on early growth of flue-cured tobacco were studied in the field. During early growth stage of flue-cured tobacco, transplanting date, methods of pasties film mulching and transplanting, fertilizer types and fertilization methods of field experiments were arranged in Wushan from2011to2013. We have explored the effects of a number of key technologies on physiological regulation of tobacco growth, nutrient uptake, yield and quality. It provided a scientific basis for rapid growth of flue-cured tobacco during early growth stage in Chongqing. Major experimental results were as follows:(1) In Chongqing, timely transplanting (Duping in Wushan, May20th) exhibited obviously motivating effects on a maximum leaf length, maximum leaf width, plant height, stem girth, effective number of leaves, the pitch, dry weights of various organs and the whole plant, leaf chemical composition coordination and microbial activity of soil. And timely transplanting (Wushan, May20th) also significantly increased the economic benefits of flue-cured tobacco. The yield, the value and middle and upper grade proportion of timely transplanting (May20th) was respectively increased by666kg/hm2,11950.50yuan/hm2,15.44%, compared with those delayed20days. Therefore, under experimental conditions, the treatment (May20th) is conducive to rapid growth during early stage and the formation of economic traits of flue-cured tobacco in Wushan.(2) In Chongqing, suitable methods of plastic film mulching and transplanting (the treatment of transplanting strong tobacco seedlings into double ridges with plastic film mulching, was named DRFS) significantly increased nitrogen and phosphorus contents of flue-cured tobacco leaves and whole plants when plants were transplanted during30days to40days, and also increased potassium uptake of flue-cured tobacco leaves and whole plants when plants were transplanted during20days to30days. For yield and value and upper grade proportion, DRFS increased by49.3%,41.2%,7.4%, as compared with NFS(the treatment of transplanting strong tobacco seedlings with no plastic film mulching). The different values on yield and value and upper grade proportion of DRFS compared with NFS was respectively17,922.00yuan/hm2,679.5kg/hm2,5.8%. In addition, DRFS significantly increased air rates of topsoil and reduced soil bulk density of topsoil when plants were transplanted for40days. Finally, the treatment of DRFS exhibited obviously promoting effects on the ability of resistance to adversity and the fomation of root morphogenesis and microbial activity during early growth stage in flued-cured tobacco. DRFS also significantly increased ground temperature, compared with other treatments. The range of variation of the ground temperature (25cm below) for DRFS was0.48-1.70℃, and soil temperature of10-25cm for DRFS increased by about1.5℃.(3) In Chongqing, the treatments (one treatment was named L0.4, which accounted for40%of total tobacco specialty fertilizer with fertilizer application in the form of liquid. the other treatment was named S0.4, which accounted for40%of total tobacco specialty fertilizer with fertilizer application in the form of solid) had particularly evident differences on plant height, maximum leaf length, maximum leaf width, the absorption of nitrogen and phosphorus and potassium when plants were transplanted for40days. The treatment (L0.4) significantly increased the value and yield, which were1.12times,1.12times of those of the treatment (the treatment was named S0.2, which accounted for20%of total tobacco specialty fertilizer with fertilizer application in the form of solid), and they were increased by7118.10yuan/hm2,303.00kg/hm2. The treatment (L0.4) and the treatment (S0.4) significantly improved the ratio of potassium to chlorine in three positons of tobacco leaves, the ratio of total nitrogen to nicotine in the upper leaves of flue-cured tobacco. And the ratio of total sugar to nicotine of treatment (L0.4) and treatment (S0.4) were more coordinated in middle and upper leaves of flue-cured tobacco. The two treatments also significantly increased root activity, root morphology, soluble sugar content, peroxidase activity and reduced membrane permeability of flue-cured tobacco when plants were transplanted for30days and40days. Furthermore, the two treatments increased the contents of microbial carbon and nitrogen and the number of microbial communities during early growth stage in flue-cured tobacco.(4) In Chongqing, plant height, maximum leaf length and maximum leaf width of the treatment (it meaned that the ratio of NPK was equal to10:30:20, was named10:30:20) were significantly increased when plants were transplanted for30days and40days. The treatment of10:30:20had obviously promoting effects on the absorption of nitrogen and phosphorus and potassium of root and stem when plants were transplanted during30days to40days. And the treatment of10:30:20had also obviously promoting effects on the absorption of nitrogen and phosphorus and potassium of tobacco leaves and whole plant when plants were transplanted during20days to40days. Comared with other treatments, the treatment of10:30:20had most obviously promoting effects on the absorption of nitrogen and phosphorus and potassium of different organs and whole plant during early growth stage of flue-cured tobacco. Compared with CK, the value and yield of the treatment of10:30:20respectively increased by16312.50yuan/hm-and285.75kg/hm-. In addition, the treatment of10:30:20could significantly improve the ratio of potassium to chlorine and the ratio of total sugar to nicotine in the middle of tobacco leaves. Finally, the treatment of10:30:20significantly increased root activity, soluble sugar content and catalase activity, and promoted the fomation of root morphology when plants were transplanted for40days.(5) In Chongqing, the treatment of Mg10), the treatment of Mg5, the treatment of Mg5B2and the treatment of B2had more obviously on promoting effects on plant height and maximum leaf length when plants were transplanted for30days and40days, and also distinctly increased the uptake of nitrogen and phosphorus and potassium of flue-cured tobacco, especially in stems, leaves and whole plants during early growth stage. The treatment of Mg10and the treatment of Mg5B2significantly increased the ability of resistance to adversity and promoted the fomation of root morphogenesis. Compared with other treatments, yield and value of the treatment of Mg5B2is highest. Compared with CK, value and yield of the treatment of Mg5B2increased by4703.57yuan/hm2,174.42kg/hm2And the treatment of Mg5B2could significantly improve the ratio of potassium to chlorine and the ratio of total sugar to nicotine in middle of tobacco leaves. In short, the treatment of Mg5B2(MgNO310kg/667m2and Borax2kg/667m2)was more conducive to rapid growth in early stage and the formation of value and yield of flue-cured tobacco.In summary, above key technologies such as timely transplanting, strong tobacco seedlings into double ridges with plastic film mulching transplanting and rational fertilization methods promoted rapid growth during early stage and the formation of value and yield and the harmony of chemical components of flue-cured tobacco in varying degrees. The specific key technologies points were timely transplanting (with the condition of the experiment, May20th is more appropriate in Wushan), strong tobacco seedlings into double ridges with plastic film mulching transplanting, fertilizer application (which accounted for40%of total tobacco specialty fertilizer with fertilizer application in the form of liquid), a fertilizer of high phosphorus and potassium contents (It meaned that the ratio of NPK was equal to10:30:20), and increasing boron and magnesium fertilizer under the local soil conditions. Through these key technologies, we can coordinate early growth and increase dry matter accumulation of flue-cured tobacco, improve physiological resistance, increase yield and quality of flue-cured tobacco. And it provided operational and technical support for rapid growth during early stage flue-cured tobacco in Chongqing. |
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