Effects Of Bacillus Subtilis On Growth Of Tobacco Rhizosphere Soils And Tobacco Plants And Quality Of Tobacco Leaves

By studying the effects of Bacillus subtilis at different use levels on the tobacco planting rhizosphere soil,the growth of tobacco plants and the quality of tobacco leaves,this study aims to explore the positive and negative effects of Bacillus subtilis on soil quality in order to regulate soil nutrients improve soil enzyme activity,ensure the normal growth and development of tobacco leaves,improve the quality and industrial availability of tobacco,and provide theoretical basis for the practical application of Bacillus subtilis to flue-cured tobacco production.The main findings are as follows:1.The application of Bacillus subtilis in tobacco plant growth period can effectively increase the total bacterial amount in tobacco planting soil,and has the best effect in the vigorous growth period;at the same time,it promoting the proliferation of actinomycetes in the earlier and middle period,and then it had inhibiting effect;in addition,Bacillus subtilis can inhibit the proliferation of fungi.2.Bacillus subtilis could significantly increased soil catalase and urease activity in in the later stage of flue-cured tobacco,and significantly increased soil the activity of sucrase during the growth period of flue-cured tobacco,The activity of soil acid phosphatase increased with the increase of the dosage of Bacillus subtilis,such activity increased first and then decreased with time.3.Bacillus subtilis had a relatively minor effect on total nitrogen,and had an effect on slowing down the loss of total phosphorus and total potassium content.The content of alkali-hydrolyzed nitrogen in the soil after final harvest improved with increase in dosage of Bacillus subtilis,and the content was obviously higher than that of the control group.After application of Bacillus subtilis,the content of available phosphorus was significantly increased during the vigorous growth period of tobacco plant.Moreover,Bacillus subtilis a relatively minor effect on available potassium in soil.Transplanting after 45 days and 75days,the content of soil organic was significantly higher than that of the control group.4.Different dosage of Bacillus subtilis had different effects on the growth and development of flue-cured tobacco.The application level of 45 kg/hm~2 was beneficial to increase the plant height,maximum leaf length and maximum leaf area in the later stage of flue-cured tobacco.Different dosage of Bacillus subtilis all increased the tobacco in the final yield,ratio of middle and upper-class tobacco,output value,average price and ECI,among which 45kg/hm~2 treatment had the best effect.After flued-cured,the physical characteristic index of middle tobacco leaves,including leaf length,leaf width,leaf weight and stem percentage,etc.was best influenced by 45kg/hm~2 treatment,then 30 kg/hm~2 treatment;the main chemical composition coordination and main chemical component utility index(CCUI)of the middle and upper tobacco leaves after flued were best effected by 45kg/hm~2 treatment,then 30kg/hm~2 treatment.The results concluded from above showed that the more appropriate application amount of Bacillus subtilis was 30-45kg/hm~2.