| Flue-cured tobacco(Nicotiana tabacum L.)is a typical K-cash crop.Potassium is involved in material metabolism,energy metabolism and other processes to improve anti-stress ability,appearance quality and aroma quality of flue-cured tobacco.Guizhou is the second largest flue-cured tobacco producing area in China.In 2016,the total output of flue-cured tobacco in Guizhou Province reached 275,000 tons,accounting for 12.89%of the total output of flue-cured tobacco in the country.And the output of Tongren flue-cured tobacco was 23,300 tons,accounting for 8.49%of the province.Tongren prefecture is one of the most ecologically suitable areas for Guizhou flue-cured tobacco.However,in recent years,the available potassium has been unevenly distributed in tobacco planting sites and the potassium has remained low in flue-cured tobacco,which seriously restricts the further improvement of the quality of flue-cured tobacco.Meanwhile,the potash fertilizer is easily prone to soil compaction,aggregate damage and other ecological problems.Potassium bacteria,as a kind of bacteria that can dissolve fixed and non-exchangeable potassium in soil,can promote the effectiveness of potassium.About 51.91%of the tobacco planting area in Tongren is yellow soil,with a highest content of total potassium to 24.50g/kg.Therefore,the screening of efficient potassium-releasing bacteria and appling to Tongren tobacco-fostering soil will promote the conversion of non-exchangeable potassium and fixed-state potassium to available-potassium in the soil of Tongren tobacco planting area.The above measures can not only improve soil potassium-supplying capacity,but also further increase the potassium content of flue-cured tobacco.Based on the above reasons,yellow soil,as the Typical Tongren tobacco-planting soil,was used to study the potassium-releasing effect of different potassium-bearing minerals and tobacco-planting soil in this study.The main results are as follows:1.The strains with high potency potassium-releasing ability and their growth characteristics were studied.148 strains of potassium-solubilizing bacteria were isolated from rhizosphere soils of Tongren alpine tobacco-growing area in Guizhou by using Alexandrov culture medium and shake-flask fermentation.The characteristics of colony morphology,physiological and biochemical characteristics and 16S rDNA identification of eight isolates with relatively high potassium release efficiency showed that T1 was Stenotrophomonas maltophilia,T2,T85,T86 and T140 were Pseudomonas putida,T33,T117 are Stenotrophomonas sp,and T107 is Pseudomonas sp.The growth curves of 8 strains of potassium-dissolving bacteria(T1,T2,T33,T85,T86,T107,T117 and T140)showed that the growth time of type "J",the stable growth time was 20h,22h,26h,26h,30h,36h,22h,22h respectively.2.The effects of eight high-efficiency potassium-releasing strains on the potassium-releasing effect of seven different potassium-bearing minerals and three tobacco-growing soils were studied.The results showed that the average relative potassium release efficiency of the eight strains of potassium-releasing bacterium to vermiculite is the highest(79.1%),and the content of available potassium in the fermentation supernatant is 8.581 ?g/mL.The average relative potassium solubilization efficiency of 8 strains to 7 different potassium-bearing minerals was T33>T107>T1>T140>T85>T117>T86>T2.The average potassium solubilization efficiency of 8 strains on yellow soil was the highest,reaching 58.2%.The average relative potassium-releasing efficiency of 8 strains to 3 different soils was T140>T33>T2>T86>T1>T107>T117>T85.Taken together,the potassium release efficiency of T33 and T140 strains is relatively good.3.The effects of T33 and T140 strains fermentation broth on the rhizosphere soil and tobacco plants of flue-cured tobacco were studied.The results showed that the treatment of T33 and T140 had more significant effects on the nutrient content in the rhizosphere than the blank group.The catalase and cellulase activities were higher at T33 after 25 days and 45 days.Treatments of T33 and T140 could significantly increase the soil microbial community richness,dominance and evenness of dominant species.Water-soluble potash fertilizer,T33 and T140 treatments had no significant differences in the physiological and biochemical indexes of roots of flue-cured tobacco.In the pot experiment,the relative expression levels of NtHAK and NtHKAl genes involved in the potassium transport of bacterial and potash fertilizers,were relatively small,the expression levels of NKT1 and NtKCl genes relative to blanks were high,the expression levels of all genes in the relative blanks of bacterial and potassium fertilizers were upregulated.In sand treatment,down-regulated expression genes were more.Water-soluble potash fertilizer had relatively good agronomic traits in flue-cured tobacco.Potash fertilizer and bacterial liquid treatment had no significant effect on the agronomic traits of flue-cured tobacco.The contents of potassium in upper,middle,and lower tobacco leaves treated with T0,T33,and T140 were similar.The potassium content of flue-cured tobacco in the middle and lower leaves was the highest with T140 treatments,the relative blank treatment increased by 55.91%and 53.1 1%respectively.The nitrogen content of upper,middle and lower tobacco leaves was the highest with T140,T140 and potassium fertilizer respectively.In this study,seven different potassium-bearing minerals and three types of tobacco-planting soils were selected to analyze the potassium-releasing effects.Strains with relatively high potassium-releasing effects were screened as reliable materials for the following studies.In addition,a comprehensive study was conducted on soil fertility and crop growth.In particular,the relative expression levels of six genes,NKT1,NTORK1,NtHAK,NtHKA1,NtTPK1,and NtKC1,in Sand and soil cultures were analyzed by q-RT PCR,which provides new ideas for further improving the potassium content of flue-cured tobacco.It can be seen that strain T140 has a significant effect on the rhizosphere soil,roots and leaves of flue-cured tobacco and can provide high-quality raw materials for the development of bio-potash fertilizer. |
PDF Full Text Request