The Effects Of Well Pit Depth And Inside Of Covering Methods On The Environment The Pit,as Well As The Growth And Quality Flue-Cured Tobacco

Well cellar transplanting technology has a strong promotion advantage in flue-cured tobacco production,but the determination of suitable well cellar depth needs to be adapted to local conditions.In addition,cup cover shows great potential in preventing and controlling soil residual film pollution.Therefore,in2021,this study designed two well cellar depths（15 cm,20 cm）and three mulching methods（film mulching M,perforated cup cover B1,non-perforated cup cover B2）in the plain tobacco area of Xiangyang City.The interaction test systematically studied the effects of different transplanting methods on the temperature,humidity,gas and heat environment in the well cellar,the growth and development of flue-cured tobacco,and the yield and quality,so as to determine the best transplanting combination,and provide technical support for preventing and controlling the residual film pollution of cultivated land and helping farmers increase their income.The main results are as follows :1.Different well cellar depth and coverage have great influence on the growth and development of flue-cured tobacco.The survival rate of tobacco seedlings treated with pit depth of 15 cm was about 11.43% higher than that of pit depth of 20 cm,and the plant height,maximum leaf length and leaf width were increased at maturity stage.Under the condition of the same well cellar depth,the root elongation stage,vigorous growth stage and field growth period of flue-cured tobacco transplanted by cup-cover transplanting（B1,B2,the same below）were extended by 8d,5d and 11 d,respectively,compared with the film mulching transplanting（M）.The total root volume,total fresh weight and main root length were increased at the rosette stage,which was beneficial to the formation of tobacco leaf yield and quality,and the effective leaf number,stem circumference and maximum leaf width were increased at the mature stage.The SPAD value of flue-cured tobacco leaves covered with cup cover after uncovering the cup was smaller than that of film mulching treatment.It took 4⁵ days to adapt to the external environment and increase the chlorophyll content.2.Different well cellar depths and coverage methods have obvious regulatory effects on the temperature,humidity,gas and thermal environment in the cellar.With the increase of the external environment temperature,the temperature in the cellar of different treatments showed an upward trend,and the temperature in the cellar with a depth of 15 cm was faster than that in the cellar with a depth of 20 cm,and the average temperature was slightly higher than 0.36℃.Under the same depth of the well cellar,before 12:00,the temperature in the cellar treated with cup-cover transplanting increased slower than that treated with film-covered transplanting.At16:00,the effect of heat preservation and moisture retention was better.The average concentration of CO₂ and O₂ in the well cellar was significantly affected by the mulching method.Under the same well cellar depth,the CO₂ concentration in the well cellar of the cup cover transplanting treatment was higher than that of the film mulching treatment,and the O₂ concentration was slightly lower,which provided sufficient raw materials for the photosynthesis of tobacco seedlings.The CO₂ concentration in the well cellar of different treatments was higher than that in the external environment,and the O₂ concentration was slightly lower than that in the external environment,but they were all within the suitable gas concentration range for the growth of tobacco seedlings.The thermal imaging temperature of cup treatment was significantly reduced by about 4℃ compared with that of film mulching treatment,which could alleviate the influence of external high temperature on the leaf surface of tobacco seedlings.There was no significant difference in the influence of the cup cover on the environment in the cellar.3.The effects of different well cellar depth and mulching methods on the quality of flue-cured tobacco were significantly different.In terms of physical properties,the leaf thickness of the well cellar depth of 15 cm was slightly lower than that of the well cellar depth of 20 cm,and the stem content was slightly higher.In terms of chemical composition and aroma,the chlorine content of the well cellar depth 15 cm treatment was 10.20% lower than that of the well cellar depth 20 cm treatment.The potassium content,potassium chloride ratio,phenylalanine,carotenoid degradation products,chlorophyll degradation products and total aroma were increased by 4.41%,16.58%,8.03%,7.19%,13.47% and 11.39%,respectively.The chemical composition is more coordinated and the content is more abundant.In general,the quality of flue-cured tobacco treated with pit depth of 15 cm is better.Under the same depth of well cellar,the maturity and leaf structure of flue-cured tobacco transplanted by cup-cover transplanting were better than those of film-covered transplanting,the total plant alkali and total nitrogen content were lower,and the sugar alkali ratio and nitrogen alkali ratio were slightly higher.The interaction between well cellar depth and mulching method had a significant effect on reducing sugar,potassium,chlorine,starch and total aroma,and had a significant effect on total sugar and disaccharide ratio.The total amount of aroma substances in 15-B2 treatment was the most,and the chemical composition was the most coordinated,followed by 15-B1 treatment with good appearance quality and sufficient aroma.4.The input cost and economic benefit of different transplanting treatments were compared.Under the same well cellar depth,the cost of film mulching was 1364.29 yuan more than that of cup cover transplanting.The overall treatment combination of15-B1 and 15-B2 had the least input cost in transplanting.Under different transplanting treatment conditions,the yield and output value of 15 cm pit depth treatment were significantly higher than those of 20 cm pit depth treatment,which increased by 9.38% and 10.54% respectively.The interaction between well cellar depth and mulching mode had a significant effect on the output value.The overall economic benefit of 15-B1 treatment was the highest.The proportion of middle and upper tobacco,yield,output value and average price were 86.31%,2260.35 kg/hm2,48104.02 Yuan/hm2 and 21.28 Yuan/kg,respectively.In summary,under the conditions of this experiment,the well cellar depth of 15 cm and the cup cover with porous holes provide a more suitable temperature,humidity,gas and heat environment for the growth of tobacco seedlings,promote the growth of the underground and aboveground parts of flue-cured tobacco,prolong the growth period of flue-cured tobacco in the field,improve the quality of flue-cured tobacco,and increase the economic benefits of flue-cured tobacco.It is a well cellar transplanting technology suitable for local tobacco production.