Biological Responses Of Flue-cured Tobacco Varieties To Soil Improvement By Biochar

Biochar is an important form of recycling agricultural and forestry wastes,because it has a large specific surface area,developed pore structure,rich active functional groups,good adsorbability and stable physical and chemical properties have great application prospects in improving soil,promoting plant growth and disease prevention and control.Different planting crops,regional scales and soil types will affect the soil improvement effect of biochar.Tobacco(Nicotiana tabacum L.)it is an important cash crop widely planted in our country.At present,there are relatively many researches on improving soil and quality of tobacco leaves by biochar,however,there is no systematic study on the biological response of different flue-cured tobacco varieties to bio-carbon improved soil.In this paper,two-factor randomized block experiment is set up to study yunyan 87,K326,G28,NC82,biological responses of six flue-cured tobacco varieties,including safflower big gold and clear leaf yellow,to biochar improved soil.The main research results are as follows:1.Agricultural characters of tobacco plants.30 days after transplanting the plant height,stem circumference,maximum leaf length and effective leaf number of tobacco are significantly different among different varieties.The plant height of yunyan 87 is the largest,51.72 cm,G28 and pure leaf yellow are relatively lower,36.26 cm and 26.18 cm respectively;the stem circumference of yunyan 87 is the largest,5.4 cm,NC82 is relatively the lowest,only 4.04 cm;the maximum leaf length of the yellow pure leaves is relatively the largest among varieties,49.96 cm,and the minimum length of G28 is 35.64 cm.Application of biochar can significantly increase the plant height,maximum leaf length and effective leaf number of different varieties of flue-cured tobacco.The increase of plant height is between-2.58 and 18.8 cm,with an average increase of 17.62 cm,among which the increase of G28 and NC82,which are high resistance to black Shank,is larger,with an increase of 31.33%and 42.44%respectively;the maximum growth rate of leaf length is between 1.76 and 7.32 cm,with an average increase of 3.38 cm,among which the variety G28 with high resistance to black shank disease increases by 20.54%,reaching a significant level;the increase of the number of effective leaves is between-0.4 and 2.2,with an average increase of 1.07 leaves.The increase of yunyan variety 87 is obvious,reaching 16.18%.The interaction effect between biochar and varieties has a significant impact on the plant height,maximum leaf width and number of effective leaves of tobacco.2.Photosynthetic characteristics of leaves.35 days after transplanting net photosynthetic rate of tobacco leaves,intercellular CO2 concentration,porosity conductivity,transpiration rate and water use efficiency are significantly different among different flue-cured tobacco varieties.In terms of net photosynthetic rate,K326 and G28 are relatively higher,while the net leaf yellow is lower;intercellular CO2 of K326 and G28 the concentration is relatively high,G28 and NC82 are relatively low;the stomatal conductance of jingyehuang was the lowest among varieties,and the transpiration rate was 0.08-0.11 mmol·m-2·s-1,K326 is relatively higher,G28 and safflower dajin are lower;the water use efficiency of G28 is the highest among varieties.Application of biochar can significantly improve the net photosynthetic rate and water use efficiency of leaves of various varieties.The net photosynthetic rate increased by 1.30-4.47μmol·m-2·s-1,with an average increase of 3.12 μmol·m-2·s-1,an average increase of 3.12 μmol·m-2·s-1,high-sensitivity black shank disease varieties clear leaf yellow,medium resistance varieties K326 and yunyan 87 increased significantly by 30.22%,24.65%and 26.93%respectively;the increase of water use efficiency is-10.52-102.59mmol·mol-1,an average increase of 50.40mmol·mol-1,medium resistance variety K326 and high resistance variety G28 increased by 52.2%and 46.61%respectively.Interaction effect of biochar and varieties on net photosynthetic rate,intercellular CO2 concentration,porosity conductivity,transpiration rate and water use efficiency all have significant effects.3.Root system development of tobacco plants.50d after transplanting the total root length,root volume,average root diameter,number of micro-roots and root surface area of tobacco plants differ significantly among different flue-cured tobacco varieties.The application of biochar significantly increased the root volume of high resistance varieties G28,NC82 and high sensitivity varieties with yellow leaves,increasing by 287.44%,438.1%and 366.62%respectively;biochar increased the average root diameter of various varieties,among which G28,NC82 and clear leaf yellow increased by 156.77%,210.61%and 175.17%respectively;biochar significantly reduced the number of micro roots of NC82 variety with high resistance,and the number of root tips,branches and overlapping numbers decreased by 43.94%,39.85%and 51.52%respectively.The interaction effect between biochar and varieties has a significant impact on the total root length,root volume,root surface area,average root diameter and micro root quantity of tobacco.4.Leaf cell protective enzyme activity.Blade passing 45 days after transplanting the activities of catalase(CAT),superoxide dismutase(SOD),nitrate reductase(NR)and sucrose invertase(INV)are significantly different among flue-cured tobacco varieties.The CAT activity of K326 and NC82 is relatively high,while that of G28 is relatively low;the SOD activity of pure leaf yellow is the highest among all varieties;The NR activity of G28 is relatively high,while that of NC82 and pure leaf yellow is relatively low;INV activity of NC82 is relatively high among various varieties.The application of biochar significantly increased the activities of POD,SOD and INV in tobacco leaves.The overall growth rate of POD activity is-5.46-117.62μg·g-1·min-1,an average increase of 585.6μg·g-1·min-1,medium resistance variety K326,yunyan 87,high resistance variety G28 and high sensitivity variety clear leaf yellow increased significantly by 188.57%,240.82%,204.76%and 333.33%respectively;the overall increase of SOD activity is-1.28-20.68 μg·g-1·min-1,an average increase of 4.25 μg·g-1·min-1,high resistance variety G28 and high sensitivity variety safflower dajinyuan increased by 22.22%and 49.17%respectively,but net leaf yellow decreased by 17.69%;INV activity increased by-0.24-1.95mg·g-1·h-1 in general.an average increase of 0.87mg·g-1·h-1,the high-sensitivity variety safflower dajinyuan increased significantly by 29.32%.The interaction effect between biochar and varieties has a significant effect on the activities of POD,SOD,NR and INV in leaves.5.Spectral characteristics of tobacco strains.Tested with portable ground features spectrometer Field Spec3 50d tobacco leaves after transplanting the spectral characteristics of different varieties have the same overall spectral shape and trend,but the characteristic reflectivity in different wave bands has certain differences.In the band of 500-700 nm,there is a big difference,which is shown as pure leaf yellow>G28>yunyan 87>K326>safflower dajinyuan>NC82.In the band of 1500-1900 nm,with the increase of wavelength,spectral reflection firstly increases and then decreases.Biochar has roughly the same influence on the spectral reflectivity of different varieties of tobacco leaves,and its spectral characteristics are obviously different in specific bands.In the 750-1350 nm band,the application of biochar reduces the spectral reflectivity of medium resistant varieties K326 and yunyan 87;in the 1500-2500nm band,the application of biochar improves the spectral reflectivity of NC82 high resistance variety and safflower dajinyuan high sensitivity variety.6.Occurrence of black shank disease of tobacco strains.Investigated various treatments occurrence of black shank disease 40 days after transplanting,the incidence rate and disease index of tobacco black Shank reached a significant level among varieties,which were manifested as safflower dajinyuan>yunyan 87>pure leaf yellow>NC82>G28>K326.The application of biochar reduces the occurrence of black shank in tobacco to different degrees,among which the incidence rate and disease index of black shank of moderate resistant variety yunyan 87,high-sensitivity variety safflower dajinyuan and pure leaf yellow all decrease obviously,the incidence decreased by 47.07%,71.43%and 75%respectively,the decrease of disease index was 49.49%,33.33%and 71.43%.7.Soil physical and chemical properties.The pH value of rhizosphere soil treated 45 days after tobacco transplanting was analyzed and the content of quick-acting nutrients,and the pH of rhizosphere soil have no significant difference among varieties;there are significant differences among varieties of quick-acting potassium,quick-acting phosphorus and alkali-hydrolyzable nitrogen in rhizosphere soil,and there are high-sensitivity varieties such as safflower dajinyuan and clear leaf yellow,the content of available potassium in rhizosphere soil of high resistance varieties G28 and NC82 is relatively high,and the content of available phosphorus in G28 and NC82 is relatively high.The alkali-hydrolyzable nitrogen of NC82 is significantly higher than that of other varieties.The application of biochar has different effects on the physical and chemical properties of soil,and biochar has different degrees of increasing effects on the pH of rhizosphere soil of various varieties;biochar obviously increases the content of alkali-hydrolyzable nitrogen in the rhizosphere soil of various flue-cured tobacco varieties,and has no obvious effect on the content of available phosphorus in the rhizosphere soil of various varieties,it has obvious promoting effect on the rhizosphere soil available potassium of medium resistance varieties K326 and yunyan 87.8.Bacterial community structure in flue-cured tobacco rhizosphere soil.Tobacco rhizosphere 45 days after transplanting soil bacterial community structure and diversity have significant differences among flue-cured tobacco varieties.The rhizosphere soil bacterial diversity of high resistance variety NC82 and high sensitivity variety pure leaf yellow is relatively high,while that of medium resistance variety K326 is relatively low;the bacterial community structure in rhizosphere soil of medium resistant variety K326 has obvious separation effect with high resistant variety NC82 and high susceptible variety pure leaf yellow.The application of biochar has no significant effect on soil bacterial diversity,but the interaction effect between biochar and varieties significantly affects bacterial richness.The application of biochar affects the bacterial dominant species in the rhizosphere soil of different varieties,and the relative abundance sequence of some dominant bacterial species changes.Biochar application reduced the relative abundance of Arthrobacter in rhizosphere soil of medium resistant variety K326,increased the relative abundance of Arthrobacter in rhizosphere soil of high resistant variety nc82 and high susceptible variety jingyehuang.Biochar to Bacillus the relative abundance of has no obvious effect;the application of biochar significantly changed the structure of soil bacterial community.The input of biochar affects the population categories of key microorganisms in the rhizosphere soil of different varieties of tobacco.The key microorganisms in the non-tobacco soil are Patescibacteria,Patescibacteria Portal,Chloroplast portal,Dehalococcoidia,Azospirillales,Xanthobacteraceae,Azospirillales and its subordinates;the key microorganism in rhizosphere soil of medium resistant variety K326 is Gaiellales and its subordinates,Acidobacteriae,Bryobacter,Bryobacteraceae and Thermoanaerobaculaceae;the key microorganisms in rhizosphere soil of high resistance variety NC82 are Blastocatellales,Pseudonocardia,Holophagae,Aeribacillus and Stenotrophobacter;there are no representative key microorganisms in rhizosphere soil of high-sensitivity varieties of yellow leaves.The above microorganisms all significantly increase after biochar input and play an important role in maintaining the biological function of soil.9.Community structure of fungi in rhizosphere soil of flue-cured tobacco.Tobacco rhizosphere soil 45 days after transplanting there are significant differences in fungal community structure and diversity among flue-cured tobacco varieties.The diversity of rhizosphere soil fungi of high-sensitivity variety pure leaf yellow and medium-resistance variety K326 is relatively high,while that of high-resistance variety NC82 is relatively low;the fungal community structure in the rhizosphere soil of the high-sensitivity variety pure leaf yellow has obvious separation effect with the medium-resistant variety K326 and the high-resistant variety NC82.The input of biochar has no significant effect on the fungal diversity in the rhizosphere soil of flue-cured tobacco varieties,but it obviously increases the fungal richness in the rhizosphere soil of medium resistant variety K326 and high-sensitivity variety pure leaf yellow.Different flue-cured tobacco varieties have the same types of main bacteria,but the proportion of abundance changes.The relative abundance of the Ascomycota in NC82 rhizosphere soil is relatively the highest,and the Basidiomycota the relative abundance among varieties is:clear leaf yellow>K326>CK>NC82.The application of biochar significantly increased the relative abundance of Mortierella and Chaetomium,and significantly reduced the relative abundance of Gibellulopsis.The application of biochar significantly affected the community structure of soil fungi,and the population categories of key microorganisms in rhizosphere soil of different flue-cured tobacco varieties changed significantly:highly enriched fungi in non-tobacco-growing soil have Eurotiomycetes classes,Aspergillus,Hypocreales,Chytridiomycota and its subordinate and Coniochaetales;in the rhizosphere soil of the medium resistant variety K326,there are high enrichment of the Ascomycota,the Eurotiales,the Aspergillaceae,the Glomerellales,the clump shell and the Paramyrothecium;the rhizosphere soil of the high resistance variety NC82 is highly enriched with Mortierellales,Mortierellaceae,Mortierellomycetes,Chrysosporium and Onygenales;the highly enriched microorganisms in the rhizosphere soil of the high-sensitivity variety pure leaf yellow have little Plectosphaerella,Cystofilobasidiales,Dothideomycetes,Cystofilobasidiaceae,Cystofilobasidium.Cladosporium,Cladosporiaceae and Wallemia.To sum up,the following conclusions can be drawn:(ⅰ)biochar can promote the growth and development of different flue-cured tobacco varieties,and has more obvious promotion effect on the plant height and number of effective leaves of high resistance to black shank disease varieties,the promotion effect on the root volume and average root diameter of high resistance varieties is obvious,while the number of micro roots is reduced.(ⅱ)Application of biochar can significantly increase the net photosynthetic rate and water use efficiency of flue-cured tobacco varieties.The increase of net photosynthetic rate of leaves of high-sensitivity black shank disease varieties including pure leaf yellow,medium-resistance varieties K326 and yunyan 87 is more significant,and the increase of water use efficiency of leaves of high-resistance varieties is more obvious.ⅲ)Biochar can significantly reduce the occurrence of black shank in flue-cured tobacco varieties,and the reduction effect on the incidence of black shank in high-sensitivity varieties is more obvious,safflower big gold and clear leaf yellow the decrease of the incidence of black shank 71.43%and 75%,the decrease of disease index was 33.33%and 71.43%.(ⅳ)Biochar obviously increases the content of alkali-hydrolyzable nitrogen in the rhizosphere soil of various flue-cured tobacco varieties,and has no obvious effect on improving the content of available phosphorus in the rhizosphere soil of various varieties,it has obvious promoting effect on the rhizosphere soil available potassium of medium resistance varieties K326 and yunyan 87.(ⅴ)Biochar application has no obvious effect on microbial diversity in flue-cured tobacco rhizosphere soil,but has significantly changed the community structure of bacteria and fungi,different tobacco black shank disease resistant varieties rhizosphere soil key microbial groups have different responses to biochar input.