Effects of Transplanting and Topping Periods on Growth and Development of Upper Leaves of Flue-Cured Tobacco

Zhu Lun; Qian Xuesong; Huang Renjie; Xiong Jing; Gao Huanye

doi:10.14083/j.issn.1001-4942.2025.03.011

Abstract：In order to explore the spatial and temporal effects of the formation of high-quality upper leav-es of flue-cured tobacco in Weining tobacco area of Guizhou Province,a two-factor randomized block experi-ment was conducted to study the effects of transplanting and topping periods on agronomic traits of upper leaves and economic traits of cured leaves of Yunyan 87.The correlations of the indexes related to ripening and senes-cence with carbon and nitrogen metabolites in the field period,and endogenous hormones in leaves with chem-ical compositions of cured tobacco leaves were also analyzed.The results showed that under T5 treatment(transplanted on April 20 and topping at initial flowering time),the upper leaves reached mature state in ma-ture period,and the cured tobacco yield,production value and top-grade tobacco rate reached the maximum values.Catalase(CAT)activity in the field period was significantly correlated with total sugar,nicotine and total nitrogen contents of cured tobacco,indicating it was one of the key enzymes affecting the coordination of chemical composition of tobacco leaves;auxin(IAA)and abscisic acid(ABA)contents significantly affected the content of reducing sugar and total sugar of cured tobacco.Under the same transplanting period,the leaf IAA,ABA and gibberellin(GA3)contents were lower on the whole when topping at initial flowering time,while zeatin-riboside(ZR)content was higher,indicating that the endogenous hormones were more coordina-ted when topping at initial flowering time,which was also the prerequisite for producing high-quality cigarettes.Comprehensive analysis showed that in Weining tobacco area,transplanting on April 20 and topping at initial flowering time could made the upper leaves grow well and obtain the best maturity in field,which was condu-cive to the formation of high-quality upper leaves,and so the economic traits of cured tobacco performed the best.