Shengling WANG,Caifu DING,Ying ZHANG,Jingjing WANG

1.Meteorological Bureau of Enshi,Enshi 445000,China;

2.Enshi Tobacco Company of Hubei Province,Enshi 445000,China

Analysis of Disease Influence on the Flue-cured Tobacco During the Growth and Development Period of Enshi in 2014

Shengling WANG1,Caifu DING2,Ying ZHANG1,Jingjing WANG1

1.Meteorological Bureau of Enshi,Enshi 445000,China;

2.Enshi Tobacco Company of Hubei Province,Enshi 445000,China

The growth of flue-cured tobacco can be significantly influenced by the temperature,sunlight,water,etc.The paper presents and analyzes the details of the disease influence on the flue-cured tobacco during the growth and development period in the high-mountainous and the middle-mountainous regions of Enshi based on the detailed climatolgical data.The results demonstrate that the most important climatic factors affecting the growth and development of flue-cured tobacco contain low temperature,even rainy,lack of sunlight and low evaporation.The deterious effects in the high-mountainous region,the heavy fog region and the flat ground are more serious compared with the middle-and low-mountainous regions,the light fog region and the sloping field,respectively.Furthermore,in order to reduce the deterious effects,helpful countermeasures are proposed favoring the growth and production of the flue-cured tobacco.

Growth of flue-cured tobacco;Influence and analysis;Disease

M eteorological factors have significant effects on cured tobacco growth and quality, for tobacco’s growth is closely related to sunshine,temperature and water, especially in resettling growth stage.In mountainous regions in Enshi,the optimal transplanting periods are from late April to middle May,when nutrient growth of tobaccos is prevented and bud differentiation advances due to low temperature and little sunshine,resulting in declining of tobacco yield and quality[1-2].

The research analyzed the effects of meteorological factors on tobacco growth and development based on diseases of tobaccos after transplanting in mountainous regions in Enshi in 2014,providing references for cultivating tobaccos and field management in later periods.

Data Source

Survey information of tobaccos

Growth vigor,leaf development and early blossoming of tobaccos were investigated from tobacco fields at 1.334 hm2in every counties of the tobacco growing regions in Enshi Tujia and Miao Autonomous Prefecture.

Meteorological information

The statistical information of meteorological factors,such as temperature,sunshine,rainfall and evaporation,during April-June 2014 were provided by Meteorological Bureaus of two county-level cities and six counties in Enshi Prefecture;temperature and precipitation in middle-mountainous regions and high-mountainous regions tobacco fields were provided by automatic meteorological stations,including the stations in Longping Village, Jianshi County,with an elevation of 1 470 m,Chunmuying Village and Xi-

Basic Introduction of disaster

Tobaccos in fields

Firstly,tobacco seedlings grew slowly and the plants were generally small,with tall and slender leaves;the seedlings were yellow or dark green, with poor growth vigor.Secondly,after transplanting for 30-40 d,it is hard for resettling.Thirdly,some tobacco plants bloomed early when the 12th-13theuphyllae grew,and some plants were much short and stems thin.For example,the small plants were just 80-90 cm in height,with standard of 110-130 cm,and the stems were just 8-8.5 cm,with standard of 8.5-11.5 cm.Fourthly,weather flecks are usually observed on the down-part leaves in few tobacco fields in previous years, but it occurred in a large area this year. Fifthly,the left leaf number reduced by 1-2 leaves.Previously,the average left leaf number reaches 20-24 leaves which are not suitable for tobacco treatment,but just reached 18-20 leavers this year,and the leaves available after treatment only totaled 14-16 leaves.Finally,the tobacco leaf grew narrow in willow leaf-shape,which is much common this year in the Prefecture.For example,the length-to-width ratio in middle parts achieved 3,and few even at 4.For healthy leaves, however,the ratio should keep in the range of 2.1-2.5.

Potential influences

At first,tobacco leaves would be malnourished,with more water,so that the curing-tolerance would be poor. Because of more rains and less sunshine,moisture content of down-part leaves would be high,and the inner materials would be lower,resulting in difficulty of curing.Specifically,dry materials of down-part tobacco leavers were few,so that tobaccos yellowed or blacked fast at curing.As for leaves in middle or upper parts,moisture content was high and the included materials were few,so that tobaccos yellowed slowly at curing,and it would be difficult for color fixing.Furthermore, under influence of successive lowtemperature and little sunshine,tobacco plants grew slowly and few fertilizers were consumed.In maturing stage when days turned good,it advanced nitrogen absorption by plants, so that tobacco leaves turned dark green and drooped,and yellow leaves were hard to be observed.Besides, total yield per unit area kept lower. Specifically,due to tobacco growth influenced by meteorological factors,the accumulation of dry materials reduced, as well as the number of left leaf,and the weight of individual leaf declined, so that general yield per unit area would definitely decrease.Finally,tobacco quality would be affected,for cured tobaccos contained less oil and leaves turned thinner.

Estimation of disease situation

Tobacco growth vigor can be divided as follows:The first refers to the vigorous growing stage without disease or insect damages.The second refers to resettling stage when tobaccos grow in order.The third refers to the period when tobacco seedlings grew poorly,with poor,small or runt seedlings.According to statistical survey,the 1st-grade tobaccos represent 60%,the 2nd-grade tobaccos 30%and the 3rd-grade tobaccos 10%in the Prefecture.What’s worse,large-area tobaccos were affected by the disasters,so that the number of leaf reduced to two leaves and 40%tobaccos were affected by the weather fleck.

Distribution characteristics

In the year,the devastated areas of tobaccos proved much more serious in high-mountainous regions compared with middle-mountainous regions and low mountains,in foggy regions compared with few-fog regions,flatlands compared with slopes. Besides,the disease of cured-tobacco was severer than that of burley tobacco and of Yunyan No.87 more serious than that of K326;the disease of down-part leaves was severer compared with upper part leaves.

Analysis of Influence Causes

Temporal and spatial distribution of meteorological factors

TemperatureAs shown in Fig.1-Fig.4,daily mean temperature of Middle-mountainous regions kept below 18℃from May 1stto May 31stfrom transplanting to resettling stage,and the temperature always maintained in the range of 13-17℃,which was 2.0℃lower compared with previous years.Since June 1st,daily mean temperature rose to over 20℃and aver-age temperature during June 1st-June 10thkept similar to the average of previous years;before May 17th,daily minimum temperature maintained in the range of 11-16℃,at or higher than 16℃from May 18th to May 31st,and over 18℃after June 1st.From June 6th to June 8th,the temperature kept below 10℃successively and over 16℃after June 1st.

In high-mountainous regions, daily mean temperature from middle May to late May was in the range of 12-16℃;average of middle May was 3.4℃lower compared with previous years and of late May was 0.4℃lower;from early June to middle June,the temperature kept in the range of 16-18℃;the average of early June was 0.8℃higher compared with previous years and of middle June was 0.3℃lower;daily minimum temperature tended to be volatile before May 31stin the range of 7-16℃;after June 1st,the temperature maintained in 13-16.5℃.PrecipitationAs shown in Table 1, precipitations in middle May and early June in tobacco fields in middle-mountainous regions kept 45%-56%lower compared with previous years;the precipitation in early May was close to the average of historical records and in late May was 60%higher;from transplanting to resettling periods,the total precipitation was 7%lower than that of previous years and rainy days were 34%more.In contrast,total precipitation in high-mountainous tobacco fields was 38%lower compared with previous years from middle May to middle June,especially in middle May and early June,but the day of raining was 45%more.

Sunshine and evaporationFrom transplanting to resettling stages,sunshine hours in middle-mountainous regions(May 1-June 10)and highmountainous regions(May 10-June 20)were 44%and 61%fewer compared with previous years.Specifically, sunshine hour in late May and early June were the least in middle-mountainous regions and kept lower by 37%-72%in different months in highmountainous regions.On the other hand,evaporation quantities in middlemountainous regions and high-mountainous regions were 59%and 57% lower compared with previous years, and the quantities were the least in late May by 70%and 72%lower.

Analysis of influence causes

Analysis of effects from meteorological factorsConsidering from meteorological factors,successive rainy days in April had adverse effects on ridging in tobacco fields,such as high moisture content in soils.With precipitation reduced in May-June, rainy days were frequent,so that evaporation quantity reduced significantly,especially after transplanting, when successive low-temperature rainy days resulted in high moisture content in tobacco fields.Consequently,tobacco roots developed not so well,and tobaccos’tolerance to disease declined,with serious weather fleck,affecting tobacco quality.

In Enshi Prefecture,average rainy days reached 56.6 d in April-June in 2014,increasing by 16.9 d compared with the same period last year,and 6.7 d compared with previous years.Besides,sunshine hour of the period just totaled 190.7 h,reducing by 287 h compared with the same period last year,and decreased by 160.8 h compared with previous years.As for temperature,mean temperature of May was 18.6℃,which was 1.1℃lower compared with previous years, and the mean temperature of June was 22.7℃which was 0.3℃lower compared with previous years.

Tobacco growth has demands on temperature and accumulated temperature.Before resettling,the number of leaf per plant has been decided actually,and the temperature of the 8th-10theuphyllae is the most closely to the number of leaf,followed by root development after transplanting[3-7].If temperature is lower and sunshine is less before or during tobacco growth for a long term,tobaccos would change from vegetative growth to reproductive growth,so that tobacco bloomed earlier.It is notable that tobacco growth requires more sunshine which promotes photosynthesis and improves yield and quality.If sunshine is less, cell division would proceed slowly,and cell elongation and intercellular space would increase,resulting in poor growth of leaf,slow accumulation of dry matter,and poor quality[8-9].On the other hand,more rainfalls would lead to soil hardening,affecting tobacco growth and leaf development,and resulting in leaching of fertilizers.In growth period of tobacco leaves,rainy days continued,with less sunshine. Hence,both of underground parts and ground parts were less supplied bynutrients,so that plants grew weakly, resulting in early blooming,thin leaf and poor inner quality.

Considering from the devastated tobaccos,the phenomenon of seedlings stop growing for a while is under influence of low temperature; non-resettling stage is mainly caused by high moisture content and poor root development;early blooming is caused by low temperature and shortterm sunshine;weather fleck is a noninfectious disease,induced by ozone harm and low temperature,supplemented by high-temperature and highhumidity weather;the decrease of the number of leaf is by lower temperature before tobacco growth and more rains in root extending stage;the poorly spread leaf is caused by lack of sunshine and nutrients.Generally speaking,low temperature,rainy days,little sunshine and less evaporation contributed to the disaster.

Analysis of diseased cured-tobaccosThe adaptation of tobaccos to climate and soils tends to be volatile upon tobacco species.Therefore,a rational distribution of tobacco species would avoid large-scale risks undertaken by tobaccos.For example,K No.326,grown in the year,is tolerant to water and fertilizer,growing better in fields compared with Yunyan No.87.In general,the disease in high-mountainous regions was much more serious in Middle-mountainous regions and low mountains,because temperature in is lower.In foggy regions,the disease was much severer because the regions have heavier rains and sunshine was poorer,affecting photosynthesis.Additionally,the disease in flatlands was much more serious compared with slopes,because tobacco fields in slopes promote water flow,and the moisture content was lower.

Table 1Meteorological factors from transplanting to resettling stages in tobaccos in middle-mountainous regions in Enshi Prefecture in 2014

Under influence of poor management technology,traditional extensive cultivation still dominates in some tobacco regions,so that tobaccos grow well in sunny days,but problems would occur in heavy weather.At first, tobacco fields are extensive and soils are not well crushed,so that root can not completely touch with soils,affecting rooting.Secondly,tobacco seedlings are not strong enough.In few places,sowing term is too later, and the cultivated seedlings are too poor at transplanting.Thirdly,water content in ridges is too high,and the hole walls are too smooth at transplanting,so that rains can not infiltrate to ridges timely.Consequently, seedlings would immerge in water for a long term,resulting in root decomposition.Fourthly,tobacco seedlings are transplanted too early in some places.For example,the seedlings would be harmed before May 5 in High-mountainous regions due to lower temperature.Finally,if additional fertilizers can not be applied timely,tobacco plants can not absorb nutrients on time,preventing seedling growth.

Measures for Preventing Disasters

Ditch cleaning and subsurface drainage

It is necessary to organize digging and cleaning work of drainage ditches, increase soil permeability,reduce moisture content of soil,and advance root growth.

To take specific measures for disaster prevention and relief

At first,it is important to take measures to promote root growth in tobacco fields where seedlings grow not so well to control the quantities of water and fertilizer,and additional biogas slurry(the rate with water at 1:1) should be applied at once.As for the areas without slurry,few potassium nitrate can be(≤150 hm2,and total N quantity was controlled at 14 kg)diluted with water at a ratio of 1:100 to be irrigated through dug holes in the location 10 cm away from roots.Secondly, it is necessary to take measures in arid tobacco fields to reduce loss caused by early blooming[10-11].Thirdly,Bordeaux mixture should be applied in the regions damaged by weather flecks. Fourthly,K fertilizers should be sprayed on leaves to adjust nutrients of tobacco leaves in later period.Fifthly,for tobaccos can not yellow,it is effective to effect a permanent cure on roots to reduce root absorption on water and nutrients.Besides,the method of preserving more branches for consumption is also available.Finally,it is necessary to guide tobacco curing work to enhance quality of cured tobaccos.

Prevention of disease and insect damages

Because of frequent rainfalls and low temperatures,root or stem diseases are hardly to be observed with abundant water in farmlands.With low temperature,few sunshine and incomplete development of tobacco organizations,tobacco leaves perform lower in tolerance to diseases.Once temperature grows,it is possible for tobaccos to be diseased by bacterial wilt,Alternaria alternate,and powdery mildew.Hence,it becomes crucial to intensify preventions in terms of drugs, especially for stems and roots dominated by bacterial wilt.

Discussions

Cured tobaccos are much sensitive to environments,and temperature, sunshine,and rainfalls are major meteorological factors affecting tobacco leaf growth[12-13].From transplanting to resettling stages,tobacco fields in Enshi are characterized by low temperature,successive rainy days and little sunshine.Therefore,it is necessary to pay attention to preventions of damages caused by rainy days and low temperature.

Furthermore,technology details need to be optimized.At first,in the context of wide application of shaft well-shaped transplanting,sowing term and transplanting period of tobaccos with different elevations should be further explored.Secondly,the manufacturing of seedling trays should take economical and practical aspects of holes into consideration to cultivate strong seedlings and save space as well.Thirdly,the necessity and importance of hardening-seedling should be underscored in order to improve tobacco tolerance.Fourthly,fertilizers should be applied with water content appropriate,followed by mulch covering.Fifthly,transplanting should be avoided too early in case of frozen stiff at low temperature.Finally,the time of mulch extension should be researched.In rainy days at low temperature,mulch extension after resettling or in early stage when tobaccos grow exuberantly would improve ground temperature and decrease the rains entering ridges,reducing moisture content of soil,which is conductive to root growth.

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Responsible editor:Xiaoxue WANG

Responsible proofreader:Xiaoyan WU

2014年恩施烤烟生长发育期病害影响原因分析

望胜玲1*，丁才夫2，张英1，望晶晶1
（1.恩施自治州气象局，湖北恩施445000；2.湖北烟草公司恩施州公司，湖北恩施445000）

该文利用详实的气象资料，从影响烤烟生长的温、光、水等主要气象要素着手，对恩施州二高山、高山烤烟生长发育期出现的病害原因进行了细致的分析。结果表明，影响烤烟生长发育的主要是因低温、连阴雨、寡照，蒸发少等气象灾害造成的，其灾害程度高山区比二高山、低山严重，多雾区比少雾区严重，坪地比坡地严重。同时，针对这种气象条件提出了相应的应对措施，为今后的烤烟生产提供了理论依据。

烤烟生长；影响原因；病害aoguan Village,Xuan’en County,with elevations of 1 640 and 943 m,and Nanping Village,Lichuan City,with an elevation of 1 130 m.

2013年度湖北省气象局科技发展基金立项项目（2013Y06）。

望胜玲（1958-），男，湖北宜昌人，高级工程师，主要从事专业气象预报方法研究等工作，E-mail：510977532@qq.com；510977532@qq. com。*通讯作者。

2015-04-30

修回日期 2015-06-01

Supported by the Science and Technology Development Fund of Hubei Weather Bureau (Grant No.2013Y06).

*Corresponding author.E-mail:May 16,2015

Received:April 3,2015 Accepted:June 1,2015