| Flue-cured tobacco is an important cash crop.The upper leaves of flue-cured tobacco play an important role in the supply of tobacco materials.In many tobacco-growing areas,the quality and utilization rate of flue-cured tobacco leaves have been greatly reduced due to the long-term continuous cropping of flue-cured tobacco and the extensive use of chemical fertilizers.Therefore,the cultivation techniques to improve the upper leaf quality of the flue-cured tobacco are of great significance to improve the availability of the upper leaf of the flue-cured tobacco and improve the utilization rate of raw materials.In this study,Yunyan 87 was used as the material to study the effects of organic fertilizer,melatonin and gibberellin on the growth and quality of upper leaves of flue-cured tobacco.The main research results are as follows:1.Compared with A2 treatment(1125 kg/hm~2organic fertilizer),A1 treatment(1500kg/hm~2organic fertilizer)increased the average plant height and maximum leaf area of flue-cured tobacco.40～80μmol/L melatonin can increase plant height,stem circumference and maximum leaf area of flue-cured tobacco.The interaction of organic fertilizer and melatonin could improve the agronomic traits of tobacco plants.The plant height of 1500 kg/hm~2organic fertilizer+120μmol/L melatonin treatment was the highest,and the stem circumference of 1125 kg/hm~2organic fertilizer+80μmol/L melatonin treatment was the highest.The leaf area of 1500 kg/hm~2organic fertilizer+40μmol/L melatonin treatment was the largest in the topping stage.2.The net photosynthetic rate of the upper leaves of flue-cured tobacco under A1treatment was higher in the early growth stage of the upper leaves and the nitrogen metabolism was vigorous,which promoted the growth of the upper leaf area.Under A2treatment,the activities of amylase and invertase in upper leaves were higher,carbon metabolism was stronger,and dry matter accumulation was increased.Both melatonin and gibberellin treatments could reduce the net photosynthetic rate,transpiration rate and SPAD value of upper leaves at maturity stage.Treatment with 80μmol/L melatonin and75 mg/L gibberellin could promote the accumulation of dry matter in the upper leaves of flue-cured tobacco.The interaction of organic fertilizer with melatonin and gibberellin affected the net photosynthetic rate of upper leaves by adjusting stomatal opening,and accumulated a large amount of photosynthates in the immature stage to improve leaf area and dry matter mass.The interaction of organic fertilizer with 1125 kg/hm~2+120μmol/L melatonin and 50 mg/L gibberellin had the best effect on the development of upper leaves.3.A2 treatment can improve the yield of tobacco leaves,but A1 treatment has a higher average price of tobacco leaves and a higher proportion of high-quality tobacco leaves,which is 3.17 percentage points higher than A2 treatment.In the melatonin treatment,the yield,output value and average tobacco price of 80μmol/L melatonin were the highest.The treatment with the highest proportion of high-grade tobacco was 120μmol/L melatonin,which was 4.06 percentage points higher than the control.In gibberellin treatment,50 mg/L gibberellin treatment had the highest yield,output value and average tobacco price,and 25 mg/L gibberellin treatment had the highest proportion of fine tobacco,which was 4.29 percentage points higher than the control.In the interaction treatment of organic fertilizer with melatonin and gibberellin,the treatment with the best yield,output value and average price gain was 1125 kg/hm~2organic fertilizer+80μmol/L melatonin+0 mg/L gibberellin,and the treatment with the highest proportion of fine tobacco was 1125 kg/hm~2organic fertilizer+40μmol/L melatonin+25 mg/L gibberellin.It was 75.58 percent.4.A2 treatment leaves are thicker but the tissue structure is loose;A1 treated leaves were thinner,with higher leaf maturity,more coordinated chemical composition and higher availability index.1500 kg/hm~2organic fertilizer can improve the sugar-alkali ratio of tobacco leaves,reduce the nicotine content of upper leaves,and make the chemical composition more harmonious.In the interaction between organic fertilizer and melatonin and gibberellin,the best treatment for maturity was 1500 kg/hm~2organic fertilizer+0μmol/L melatonin+50 mg/L gibberellin,and the highest treatment for oil content was 1500 kg/hm~2organic fertilizer+120μmol/L melatonin+50 mg/L gibberellin.The highest sensory quality scores of upper and middle leaves were 1500 kg/hm~2organic fertilizer+120μmol/L melatonin+0 mg/L gibberellin treatment,which had good aroma,sufficient aroma,appropriate nicotine content,relatively high total sugar and sugar base,and insufficient potassium content.In conclusion,organic fertilizer of 1125 kg/hm~2can promote carbon metabolism and substance accumulation in upper leaves of flue-cured tobacco.Both melatonin and gibberellin can promote photosynthesis,substance accumulation and maturation of upper leaves,and the interaction of the three can significantly promote the growth and development of upper leaves.Increasing the amount of organic fertilizer is helpful to improve the proportion of high-grade tobacco,sensory quality,chemical composition coordination and industrial availability of tobacco leaves.Spraying 120μmol/L melatonin could improve the yield and output value of flue-cured tobacco,and spraying50 mg/L gibberellin could improve the agronomic and economic characters of tobacco.The sensory quality score of upper leaves was the highest when treated with 1500 kg/hm~2organic fertilizer and 120μmol/L melatonin,and the availability of chemical components of tobacco leaves treated with 1500kg/hm~2organic fertilizer and 120μmol/L melatonin and 50 mg/L gibberellin was the best.The best treatment for promoting the development of upper leaves and improving the tissue structure of tobacco leaves was 1125 kg/hm~2organic fertilizer+120μmol/L melatonin+50 mg/L gibberellin.The best treatment to improve the quality of upper leaves was 1500 kg/hm~2organic fertilizer+120μmol/L melatonin+25 mg/L gibberellin. |
PDF Full Text Request