Studies On Sulphur Nutrition Of High-quality Flue-cured Tobacco Production In Fujian Province

Field investigation, indoor soil-culture, pot experiment, field experiment and sense appraisal of high grade leaf were conducted to study the characteristics of mineralizing of four different organic fertilizers with sulphur and the organic sulphur of soil, the rule of the transference of S fertilizer applied in different soils, and investigated the case of the smoking assessment of representative tobacco leave samples, the indexes of abundance and shortage of available S in soil with flue-cured tobacco and optimum content of S in tobacco leaf were presented, soil sulphur supplying capacity in Fujian tobacco planting area was been aprraised as well.1.The results of indoor soil-culture of different soils showed soil available sulphur had been increased after culturing for 10 days, the amount of increased soil available sulphur was in the following order: dark mud field(11.1 mg/kg)>dark and sand mud field(8. 9 mg/kg)>paddy field(7. 6 mg/kg)>yellow mud field(3.0 mg/kg)> yellow podzolic paddy field(1.3 mg/kg) and tidal field(1.3 mg/kg).The characteristics of the mineralizing of the soil organic sulphur have some relations to its organic content.Different organic fertilizer with sulphur cultivated in different soils experiment indicated: with the same fertilizer application (12.50 g/kg or 25.00 g/kg), cake fertilizer took the most great effect on soil available sulphur content, and that of chicken manure and duck dung, rice straw took the least effect on soil available sulphur. This had some relations with the S content of the four organic fertilizers. The release rates of S were different, the cake fertilizer' s relase rate was the highest, attained 43. 93%. And that of chicken manure and duck dung, were 36. 41% and 34. 77%. The release rate of the rice straw was the lowest, only 21. 63%, this has some relations to its high C/N.By way of supplying the equal amount of S fertilizer such as (NH₄)₂SO₄, k₂SO₄, MgSO₄ and CaSO₄ (applied S 60 mg/kg) , culturing one week, the content of soil available sulphur of tidal field and dark mud field increased most (50. 4 mg/kg～53.6 mg/kg), and that of dark and sand mud field and paddy field (41. 8 mg/kg～50. 7 mg/kg), the content of soil available sulphur of yellow mud field and yellow podzolic paddy field increased least (41.4 mg/kg～45. 0 mg/kg) . At the first week of the culturing, the rate of sulphur absortption was low, only 10. 67%～31. 00%; and when the culture time extended to forteen weeks the rate of sulphur absortption increased evidently, reached 51. 83%～84. 50%.The rates of sulphur absortption were different with the different amount of sulphur fertilizer application. After three weeks culturing, as the sulphur fertilizer application was increased from 30 mg/kg to 150 mg/kg, the rate of sulphur absortption about yellow mud field was decreased from 56. 33%～63.67% to 47. 20%～48. 00%, and the rate of sulphur absorption about the tidal field was decreased from 30. 00%～32. 67% to 19. 60%～22. 40%.2. Correlation research of soil available S and flue-cured tobacco S uptake indicated: the content of soil available S (Ca(H₂PO₄)₂-T) had good relationship with tobacco-leaf, tobacco-root, tobacco-stem and whole tobacco plant S uptake, the correlation coefficient were up to 0.973, 0.962, 0.978 and 0.964 separately, being extremely remarkable positive in correlation. Ca(H₂PO₄)₂-T was a suitable way to estimate soil available S in Fujian flue-cured tobacco planting area.3. Tobacco plants growth vigor, physiology metabolism, biomass and the S content were differ in each treatment. During the experiment, there was no symptom of sulphur deficiency took place in low level of soil available sulphur treatment tobacco plants, and also no symptom of sulfur poisoning took place in high level of soil available sulphur treatment tobacco plants, but these tobacco plants' normal growth metabolize had been differently depressed. 30 days, 60 days and 80 days after transplanting, the tobacco plants of the soil available sulphur content between 22.1mg/kg and 40.1mg/kg treatments had good growth vigor. During the fast growing stages of the tobacco plants, when the soil available sulphur was 40.1mg/kg, chlorophyll, Chla,Chlb and soluble protein of tobacco leaf reached the peak value of 3. 22 mg*g^-1Fw, 2. 33 mg*g^-1Fw, 0. 89 mg*g^-1Fw and 14. 15 mg*g^-1Fw respectively, MDA content reached the lowest value with 0. 84 nmol^-1g^-1pro. As the soil available sulphur was 28.3 mg/kg, nitrate reducetase and Car content of the tobacco leaf reached the peak value of 8. 43 ugNO₂-N*g^-1Fw*h^-1 and 0. 61 mg*g^-1Fw. When the tobacco plants had been cropped, the amount of the accumulation of dry matter in plant and in leaf reached the peak value of 53. 23 g/plant and 30. 10 g/plant respectively when the soil available sulpur was 22.1 mg/kg(S4 treatment). The tobacco root system of S4 treatment grew well, it had much fine root and the root color was bright yellow, the root volume was 45.75 ml, the maximum root length was 21.45 cm.Considered every aspects of tobacco plants growth vigor, biochemical and physiological index, biomass and the root system growth of each tobacco treatment in fast growing stage and in crop stage: the soil was recommended as insufficient S when the content of soil available sulphur was under 15 mg/kg, and slightly insufficient S when it was 15 mg/kg～22 mg/kg, suitable when it was 22 mg/kg～40 mg/kg, sufficient when it was up to 40 mg/kg, especially when it attained 52 rag/kg.4. The results of field experiment of different amount of S application showed: when the content of soil available sulphur was 7.6 mg/kg, yield and output value of flue-cured tobacco reached the peak value of 3034. 35 kg/hm² and 27187. 78 yuan/hm² while the sulphur fertilizer application was 82.5 kg/hm²(D treatment), mean value and the ratio of high-rate leaves reached the peak value of 9. 25 yuan/kg and 48. 74% while the sulphur fertilize application was 60.0 kg/hm²(C treatment). When the content of soil available sulphur was 22. 1 mg/kg, yield and output value of flue -cured tobacco and the ratio of high-rate leaves reached the peak value of 2512.50 kg/hm², 24672.75 yuan/hm² and 43.9% respectively while the S application was 37.5 kg/hm²(B treatment); The average price of flue-cured tobacco value reach the peak value of 10.00 yuan/kg while the sulphur fertilizer application was 0.0 kg/hm²(A treatment).5. Smoking assessment of 122 representative samples of high-rate and mid-rate tobacco leaf in Fujian main tobacco planting areas were conducted, the result showed: when the total S content of the tobacco leaves was 0. 66%～0. 69%, the smoking aggregate score pointed highest, the value of tobacco aroma, the characteristics of the smoke components and taste were best. The quality and the quantity of aroma were relatively suitable and there was less offensive odor, had mellow, clear, ventilate and exquisite smoke characteristic, their aftertastes were comfortable, the total tastes were harmonious, and had adequate strength. As the content of S increased, the quality and quantity of the aroma in tobacco leaves decreased obviously.6. On the basis of the index proposed in the pot experiment, we can make a comment to the situation of the potassium in Fujian tobacco planting area by analyzing 2, 242 representative soil samples. The research considered that content of soil available sulphur is 0.40 mg/kg～514.20 mg/kg, averaged 27.91 mg/kg in Fujian. The average content of soil available sulphur in Nanping, Longyan and Sanming tobacco planting area are 30.14 mg/kg, 29. 27 mg/kg and 25.81 mg/kg respectively. The three great tobacco planting areas all had S-deficient soils. The ratio of the soils which had low ability of sulphur supply were 48. 12%, 52. 51% and 60.31% in Longyan, Nanping, Sanming respectively. There are 21. 58%, 27. 20% and 35. 36% soils in Longyan, Nanping, Sanming which were serious S-dificient.