Effects Of Different Substrates On Seedling Quality,yield And Quality Of Tobacco Leaves Under Air Rooting Principle

In order to further enrich the existing flue-cured tobacco seedling methods and cultivate high-quality flue-cured tobacco seedling,this study used the existing floating seedling as the control,and applied the multi-layer cycle mechanical seedling facilities.From December2019 to July 2020,the effects of different seedling substrate formulations based on the principle of air root preparation on the quality of flue-cured tobacco seedlings and the yield and quality of flue-cured tobacco leaves after planting were discussed.The main research results are as follows:1.Influence on tobacco seedling quality.Compared with the existing floating tobacco seedlings,the stem circumference,seedling height,maximum leaf area,dry matter accumulation,leaf chlorophyll relative content(SPAD value),root activity and leaf nitrate reductase activity of tobacco seedlings treated with different seedling substrates were better than those of the control.The seedling emergence rate and strong seedling rate of treatment 2(80% existing peat seedling substrate + 20% sterilized fine loess)were the highest,which were significantly(p<0.05)higher than those of control 12.4% and 10.3%,respectively.2.Effects of transplanting tobacco seedlings on main agronomic traits in field.After transplanting tobacco seedlings with different treatments,the main agronomic traits of tobacco plants in the field were measured 7 days after topping.The results showed that compared with the control,the plant height,internode length,stem circumference and leaf area of the maximum leaf of tobacco plants treated with different seedling substrates were higher than those of the control.The plant height,pitch,stem circumference and maximum leaf area of tobacco plants in treatment 2(80% existing peat seedling substrate + 20%sterilized fine loess)were the highest,and the plant height and pitch were higher than those of the control 9.9% and 7.0%,respectively.The stem circumference and maximum leaf area were significantly higher than those of the control 18.8% and 23.0%(p<0.05).3.Effects on yield and quality of transplanted tobacco seedlings.Compared with the control,the proportion,1)yield and output value of the superior tobacco leaves in the main economic status indexes of different treatments were higher than those of the control,and the proportion,yield and output value of the superior tobacco leaves in treatment 2(80% of the existing peat seedling matrix + 20% of the sterilized fine loess)were the highest,among which the yield of tobacco leaves was higher than 4.7% of the control,and the proportion and output value of the superior tobacco leaves were significantly higher than 17.1% and12.7% of the control(p<0.05).2)The physical characters of B2 F and C3 F grade tobacco leaves were better than the control;3)The availability index(CCUI)of main chemical components of B2 F and C3 F grade tobacco leaves was higher than that of the control,and the treatment 2 was the largest;4)The total scores of appearance and sensory quality indexes of B2 F and C3 F tobacco leaves were higher than those of the control,and the treatment 2was the largest.The total scores of appearance quality indexes of B2 F and C3 F tobacco leaves were higher than 4.6% and 4.6% of the control,respectively.The total scores of sensory quality indexes of B2 F and C3 F tobacco leaves were higher than 4.5% and 2.9% of the control.In summary,the results showed that the quality of tobacco seedlings at adult stage was better than that of the seedlings cultivated by the existing floating seedling technology by using the multi-layer circulating mechanical seedling facility based on the principle of air whole root and adopting the appropriate seedling substrate,which was beneficial to the growth and development of tobacco plants after transplanting to the field,and had good effect on improving the yield and quality of tobacco leaves.The results of this study provide a theoretical basis and a new way of tobacco seedling cultivation technology for the application of multi-layer circular mechanical seedling facilities based on the principle of air rooting in flue-cured tobacco seedling.