Effects Of Different Substrate Treatments On The Growth And Development Of Tobacco Seedlings In Shallow Water

Seedling raising is the primary link in tobacco production.The quality of tobacco seedlings is the key to obtaining high-quality tobacco leaves.It directly affects the growth and development of flue-cured tobacco fields,the yield and quality of tobacco leaves,and the industrial availability of tobacco leaves.Peat and other non-renewable natural resources,reducing its use in intensive seedling raising is of great significance to saving resources.In this study,the method of shallow water seedling cultivation was adopted,and the existing floating seedling peat substrate was used as the control(CK,peat content≥45%),and five different volume ratios were set with dry cow dung organic fertilizer,yellow soil,peat,and puffed perlite as the volume ratio.Matrix formula treatment,T1:10%dry cow dung organic fertilizer+35%yellow soil+40%peat+15%puffed perlite,T2:15%dry cow dung organic fertilizer+35%yellow soil+35%peat+15%Puffed perlite,T3:20%dry cow dung organic fertilizer+35%yellow soil+30%peat+15%puffed perlite,T4:25%dry cow dung organic fertilizer+30%yellow soil+30%peat+15%Puffed perlite,T5:30%dry cow dung organic fertilizer+25%loess soil+30%peat+15%puffed perlite,and discussed the effect of different substrate treatments on the emergence,seedling rate and seedling stage of Yunyan 87 under shallow water seedling cultivation Tobacco seedling quality,and its effects on physiological and biochemical characteristics of tobacco seedlings.The main results are as follows:1)The physical and chemical properties and main nutrient contents of the substrates in each treatment:the physical and chemical properties of the five treatment substrates are all within the suitable growth range for tobacco seedlings,the bulk density of the substrates is between 0.454 and 0.661 g/cm~3,and the total porosity is between 67.7 and 76.1%.The p H value was between 6.69 and 6.98,and the electrical conductivity was between 0.784 and2.149 m S/cm.The gas-water ratio of T1 and T2 was higher than that of the control,but the ratio of T3 to T5 was lower than that of the control.The contents of total phosphorus,total potassium,available phosphorus and available potassium were significantly higher than those of the control.2)Effects of different substrate treatments on the emergence and seedling rate of tobacco seedlings,and the quality of tobacco seedlings at the seedling stage:14 days after sowing,there was no significant difference in the emergence rate of each treatment,all reaching more than 96%;45 days after sowing,T1～The seedling formation rate of T5 was lower than that of the control;the quality indicators at the seedling stage:plant height,stem circumference and leaf area of T1～T3 were higher than those of the control;the dry weight of the whole tobacco seedlings of T1 and T2 were increased by 10.8%and 10.8%compared with the control,respectively.9.9%;the fresh-to-dry ratio of the whole plant T2-T5 was higher than that of the control,and the dry matter-to-shoot ratio of the tobacco seedlings T1-T2 was higher than that of the control.3)Effects of different substrate treatments on the physiological and biochemical characteristics of tobacco seedlings at the seedling stage:in the seedling stage,the total chlorophyll content of each treatment was higher than that of the control;the root vigor of T1～T3 increased by 44.3～48.5%compared with the control,the nitrate reductase activity of T1～T3 increased by 29.4～35.5%compared with the control;the superoxide dismutase,catalase,peroxidase activities and malondialdehyde content of T1 and T2 were lower than those of the control;T1 Compared with the control,the soluble protein content of T2 and T3increased by 40.2-71.3%,and the soluble sugar content of T1-T5 increased by38.0%-131.3%compared with the control.4)Correlation,principal component analysis and comprehensive evaluation:The main physical and chemical properties of the substrate have varying degrees of correlation with the emergence and growth of tobacco seedlings,dry matter accumulation,and physiological and biochemical indicators;The principal component analysis of 13 individual indicators such as protein and soluble sugar content was used to determine the weight of each related indicator of tobacco seedlings,and a comprehensive evaluation model was constructed to calculate the comprehensive score.T5.To sum up,the results show that under the method of shallow water seedling raising,the flue-cured tobacco seedling matrices composed of organic fertilizer,yellow soil,puffed perlite and peat have different effects on the growth and development of tobacco seedlings.Dry cow dung organic fertilizer+35%yellow soil+40%peat+15%puffed perlite),T2(15%dry cow dung organic fertilizer+35%yellow soil+35%peat+15%puffed perlite)and T3(20%dry cow dung organic fertilizer+35%yellow soil+30%peat+15%puffed perlite)is better,and T2 is the best.Compared with the conventional floating nursery substrate,the substrate formula of T1～T3 in this study reduces the consumption of peat resources by 11.1%-33.3%.Guiding significance and reference value.