Effects of sulfur application rates on sulfur utilization，yield and quality of flue-cured tobacco in regions with different sulfur levels

【Objective】The study examined the effects of sulfur application rates on sulfur utilization，the yield and quality of flue-cured tobacco in regions with different background soil sulfur levels，analyzed the relationship between sulfur content in tobacco leaves and sulfur application rates，evaluated the absorption and utilization efficiency of sulfur in flue-cured tobacco to provide scientific basis for rational sulfur fertilization and high-quality tobacco production. 【Method】A two-year field experiment was conducted in typical sulfur-deficient（available sulfur content 6.25 mg/kg）， potential sulfur-deficient（available sulfur content 16.03 mg/kg），and sulfur-sufficient（available sulfur content 26.55 mg/kg）flue-cured tobacco growing regions in Nanping，Fujian. Different sulfur application levels（S1：30.0 kg/ha；S2： 60.0 kg/ha；S3：90.0 kg/ha）were applied with no sulfur application（CK）as a control. Sulfur contents in different parts of flue-cured tobacco under different treatments were measured，and sulfur accumulation and fertilizer use efficiency were calculated. After flue-curing，tobacco output value were assessed，and middle leaves（C3F）were selected for chemical composition analysis and sensory quality evaluation.【Result】Compared with CK，sulfur application could increase the sulfur content of tobacco leaves. In the sulfur-deficient and potential sulfur-deficient regions，the S3 treatment showed fine effects，with an increase of 12.75%-30.62% and 31.45%-36.52% respectively. In the sulfur-sufficiency region，the S2 treatment showed fine effects，with an increase of 8.71% to 16.30%，the increase reached significant level（P<0.05，the same below）. Sulfur application significantly increased the flue-cured tobacco total sulfur accumulation（6.11%-25.04%） and tobacco leaf sulfur accumulation（7.79%-37.19%）in the 3 experiment fields. In the sulfur-deficient and potential sulfur-deficient regions，the S1 treatment had the highest apparent utilization rate of sulfur fertilizer（RE），sulfur agronomic efficiency（AE），and sulfur partial productivity（SEP）. In the sulfur-sufficient region，the SEP under S1 treatment was the highest，and there was significant difference between treatments. The S2 treatment showed the highest total potassium content in flue-cured tobacco leaves in both sulfur-deficient and potential sulfur-deficient regions，significantly increasing it by 11.68%-16.52% compared to the CK. The sensory quality of flue-cured tobacco was the best under the S1 treatment in sulfur-deficient and potential sulfur-deficient areas. However，in the sulfur-sufficient area，sulfur application reduced the sensory quality of the flue-cured tobacco. In sulfur-sufficient region，the relationship between sulfur application rate and the total potassium content in flue-cured tobacco followed a quadratic equation curve. The total potassium content reached its maximum value when the sulfur application rate was 30 kg/ha.【Conclusion】In the tobacco-growing areas of Fujian，a sulfur application rate of 30-60 kg/ha is recommended for sulfur-deficient and potentially sulfur-deficient regions，while sulfur input should not exceed 30.0 kg/ha in sulfur-sufficient regions. In addition，the current structure of potassium fertilizer application in flue-cured tobacco production should be adjusted in a timely manner，with a reduced use of potassium sulfate.