| An experiment of field investigation and laboratory analysis were conducted to study the status and influential factors of magnesium?Mg?content and its effect on flue-cured tobacco quality in flue cured tobacco in red soil in the middle altitude region in Qujing.721 samples of flue cured tobacco from 9 tobacco growing counties?districts?,24 townships and 7 main flue cured tobacco varieties and their corresponding climatic and soil indexes were collected from the tobacco growing areas of red soil in mid altitude of Qujing.To analyze the overall distribution characteristics of Qujing flue-cured tobacco area of magnesium and different growing counties?districts?of flue-cured tobacco magnesium content under different conditions and varieties;the influence of regional climate and soil factors on the magnesium content of flue-cured tobacco,as well as the relationship between the magnesium content of flue-cured tobacco and tobacco quality indexes,the main conclusions are as follows:1.The content of Mg in 721 samples of flue-cured tobacco in the middle altitude red soil area of Qujing was analyzed.The average content of Mg in flue-cured tobacco in this area was 0.42%,which was concentrated in 0.20%-0.80%.The overall trend was normal distribution,the coefficient of kurtosis was 0.175,and the coefficient of deviation was 0.707.Among them,the obvious Mg deficiency?<0.2%?ratio was 7.68%;the mild deficiency?0.2%-0.4%?ratio was 45.54%,the normal range?0.4%-1.5%?ratio was 46.78%,it can be seen that although the average content of flue-cured tobacco in this area was suitable,most of them are still in the abnormal level,and attention should be paid to the nutrition balance of Mg fertilizer.2.The variation of Mg content in producing areas and varieties of flue-cured tobacco of the red soil area of middle altitude in Qujing was analyzed.?1?From the various producing areas: The average content of Mg in Shizong flue-cured tobacco is 0.59%,which was the best.The average content of Mg in Huize and Fuyuan was 0.41% and 0.42%,which reached the range of normal Mg content.The average content of Mg in the remaining 6 regions?Malone,Luliang,Luoping,Zhanyi,Xuanwei,Qi Lin?was at the level of mild Mg deficiency,It was worth noting that more than 70% of the flue cured tobacco in Malone,Luliang,Xuanwei and Kirin four are in a state of mild Mg deficiency or obvious Mg deficiency.?2?From the tested varieties: The average content of the three main varieties of K326,Yunyan 85 and Yunyan 97 was in the suitable range,The average content of Mg in K326 flue-cured tobacco was the largest?0.53%?,the average content of Mg in Yunyan 85 and Yunyan 97 was 0.43% and 0.41%,respectively.NC297 samples with up to 82.76% of flue-cured tobacco were characterized by mild Mg deficiency or obvious Mg deficiency,However,only 3 of the 12 samples of flue-cured tobacco obtained by NC102 showed good performance,which should be paid more attention to further determining the characteristics of their varieties.3.The influence of climate factors on the content of Mg in flue-cured tobacco in the middle altitude of Qujing was studied.?1?Although 9 flue-cured tobacco areas in the middle altitude area,there are differences in sunshine duration,temperature and moisture.The average temperature of the early procreation was lower than the average temperature in the later period,precipitation in the early stage of growth was significantly lower than that in late growth,the Mg content of flue-cured tobacco in the whole growth period of the cumulative number of hours of sunshine for 647.83 h,the average temperature of procreation was 17.82?,the average temperature of the late growth period was 19.13?,the effective total accumulated temperature that above 17? was 189.17?,the total rainfall in the early stage of fertility is 141.34 mm,when the total amount of rainfall is 654.12 mm in the late growth period,it was the most suitable.?2?The content of Mg in flue-cured tobacco in this area is linearly and negatively correlated with the sunshine hours from late April to late August,The Mg content of flue-cured tobacco was two element linear regression with the average temperature in the early and late stages,rised as the average temperature rised;the content of Mg in flue-cured tobacco was related to the positive correlation between precipitation and stable temperature at above 17 degrees centigrade.4.The effect of soil factors on the content of Mg in flue-cured tobacco in the middle altitude of Qujing was studied:?1?The average value of soil p H in 9 flue-cured tobacco areas was 6.27,to meet the basic needs of the growth of Flue-cured Tobacco;the content of organic matter is rich?3.77%?,reaching a high fertility level;soil alkaline nitrogen(124.33 mg·kg-1),available phosphorus(32.77 mg·kg-1)and available potassium(197.95 mg·kg-1)and avaliable Fe(54.57 mg·kg-1)all at the middle level,those kinds of fertilizer should be added to the specific situation as appropriate;the average content of exchangeable calcium 2592.27 mg·kg-1,the average content of exchangeable Mg 314.10 mg·kg-1,were at the high level range.?2?The content of Mg in flue-cured tobacco in this area increased first and then decreased with the increase of soil p H,soil alkaline nitrogen,available phosphorus and available potassium content,with the increase of soil exchangeable calcium content,the trend of first sudden drop and then rise;increased with the increase of soil organic matter and exchangeable Mg content;decreased with the increase of soil available iron.5.Studied the relationship between the content of Mg in flue-cured tobacco and the quality of tobacco leaves in the middle altitude of Qujing: The influence of the increased of Mg content on the indexes of flue cured tobacco was mainly reflected in the conventional chemical composition,nutrient allocation,polyphenol synthesis and sensory quality of flue-cured tobacco.At the same time,with the increased of Mg content in flue-cured tobacco,leaf maturity,color,oil and leaf structure of each index score increased,leaf weight,leaf length,leaf density,filling value,equilibrium moisture content of the index was also increased,but the content of potassium and polyphenolic substance content increased with Mg the content of flue-cured tobacco and decreases slowly. |
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