Study On Difference Of Photosynthesis, Yield And Quality Of Flue-cured Tobacco At Different Altitudes In Enshi

Pot and field experiment were conducted at the altitude of 500 m, 900 m and 1300 m in Enshi Autonomous Prefecture of Hubei to study difference of photosynthesis, yield and quality of flue-cured tobacco K326, Yunyan87, and Zhongyan103, which genetic background is different. Changes of gas exchange parameters, photosynthetic pigment content, RuBPcase initial activity, and chloroplast ultrastructure after full expansion of middle leaf, diurnal changes of photosynthesis and relationship with environmental factors, changes of carbon and nitrogen as well as some secondary metabolites, analysis of yield, quality and aroma-style, and relations between photosynthetic production capacity and yield and quality were studied in this paper. The main conclusions were as follows:(1) Photosynthetic function declined after full expansion of leaf in flue-cured tobacco. With the increase of altitude, photosynthetic function decline was delayed. The decline rate of Pn, photosynthetic pigment content, and RuBPcase initial activity were reduced, disintegration time of chloroplast ultrastructure and thylakoid lamellar structure were postponed, active photosynthesis duration (APD)was prolonged, leaf Source Capacity (LSC) and per area leaf source capacity (PALSC) were increased. Pathway analysis showed that the direct action of APD affecting LSC and PALSC was largest, therefore, prolonging APD was the main measure of increasing photosynthetic production capacity of leaf in flue-cured tobacco.(2)With the increase of altitude, daily photosynthesis(∑Pn), per area daily photosynthesis(PA∑Pn), and water use efficiency (WUE) were increased. At altiude of 900 m, flue-cured tobacco's leaves had the highest Daily transpiration(∑Tr) and per area(PA∑Tr), followed by altiute of 500 m. In the sunny noon, flue-cured tobacco's leaves appeared photosynthetic inhibition, and the degree was lightened with the increase of altitude. High temperature was the main limitied factor affecting photosynthesis and it could exacerbate photosynthetic inhibition. The main physiological factor affecting diurnal change of photosynthes was stomatal conductance(Gs), and ecological factors were different with altitude variation. At altitude of 500 m, ambient temperature (Ta) and air relative humidity (RH) were the main limitied factors to Pn. At altitude of 900 m, Pn mainly was impacted by photons flux density (PFD) . At altitude of 1300 m, Ta and RH were the main factors affecting Pn.(3) There were some differences on photosynthetic physiological characteristics among flue-cured tobacco growing at different altitudes. With the increase of altitude, adaptability and utilization ability for strong light increased, while it reduced for weak light. Flue-cured tobacco growing at high altitude had higher efficiency of carbon uptake than at low altitude. Response curves of Pn to PFD of flue-cured tobaccos'leaves at different altitudes were simulated with equation of Pn =Pnmax (1-C0exp(-aPFD/ Pn max), and equation of response curves of Pn to Ci was Pn=Pn max (1-exp(-a Ci / Pn max)-Rd.(4) Photosynthetic products mainly accumulated in the form of starch after full expansion of leaf in flue-cured tobacco. Content of starch and total carbohydrate, specific leaf weight, and ratio of carbon to nitrogen increased firstly and decreased afterwards in the process of leaf development. With the increase of altitude, the accumulating time of assimilate and dry matter were prolonged. The variation of content of starch and total carbohydrate, specific leaf weight, and ratio of carbon to nitrogen to days after full expansion were simulated with quadratic polynomial. Leaf N concentration was declined after full expansion, its variation was simulated with progressive regression model. The decline rate of leaf N concentration reduced with the increase of altitude. There were significant positive correlation between Leaf N concertration, Pn and chlorophyll content .(5) Effects of altitude on LSC, PALSC,∑Pn and PA∑Pn reached very significant level, however, only PALSC impacted by variety was significant level. The interactive effects of altitude and variety on every indexs for photosynthetic capacity reached very significant level. With PALSC, LSC,PA∑Pn and∑Pn as evaluation index for photosynthetic production capacity, different combinations of altitude and varieties were cluster analyzed, it had been divided into three categories, that were strong type including Yunyan87-1300 m and Zhongyan103-1300 m, medium type including K326-900 m, K326-1300 m and Yunyan87-900 m, lower type, including K326-500 m, Yunyan87-500 m and Zhongyan103- 500 m.(6) The effects of altitude and variety on most indexs for yield and quality production were significant. The interactive effects of altitude and variety on every indexs for yield and quality reached significant level. With weight per leaf and population yield as evaluation indexs for yield, different combinations of altitude and varieties were cluster analyzed, it had been divided into three categories, that were high-yield type including Zhongyan103-1300m, Zhongyan103-900m and Yunyan87-1300m, middle-yield type including Zhongyan103-500m, Yunyan87-900 m, Yunyan87-500m, K326-900m and K326-1300m, low-yield type, including K326-500m. With output value and average price as evaluation indexs for tobacco growers'income, different combinations of altitude and varieties were cluster analysised, it had been divided into three categories, that were high-income type including K326-900 m, Yunyan87-500m, Yunyan87-900m, Yunyan87-1300m and Zhongyan103-1300m, middle-income type including K326-1300m, Zhongyan103-900m,low-income type including K326-500m and Zhongyan103-500m. With smoking quality and appearance quality as evaluation indexs for tobacco quality, different combinations of altitude and varieties were cluster analysised, it had been divided into three categories, that were better quality type including K326-900m and Yunyan87-900m, middle quality type including K326-1300m, Yunyan87-500m, Yunyan87 -1300m, Zhongyan103-900m, Zhongyan103-1300m, lower quality type including K326-500m and Zhongyan103 -500m.(7) With grade C3F of flue-cured tobacco leaves as reference materials produced at different regions including Pingdingshan area in Henan, Qujing area in Yunnan, Bijie area in Guizhou, Dunhua area in Jilin, and Chongqing area which have different aroma type style, different combinations of altitude and varieties were cluster and discrimination analysised. Cluster analysis indicated that aroma type style showed great difference not only in large scale regions but also at different altitudes in the same region. Discrimination analysis indicated that three sample were classified as neutral tend to full aroma type in Chongqing including K326-1300 m, Zhongyan103-900 m, Zhongyan103-1300 m, three sample were classified as full aroma type in Henan including K326-900m, Yunyan87-500m, Zhongyan103 -500 m, two sample were classified as faint aroma type in Yunnan including Yunyan87-900m and Yunyan87 -1300m, one sample were classified as neutral aroma type in Jilin which was K326-500m.(8) Overall, altitude of 900 m in Enshi was the most suitable area for tobacco cultivation, followed by altitude of 1300m. Flue-cured Yunyan87 had stronger adaptability, exhibited more suitable photosynthetic production capacity and better yield and quality at every altitude. K326 was most appropriate at altitude of 900 m, while Zhongyan103 was most appropriate at altitude of 1300 m.