The Eddects Of Drought Stree On The Yield Chemical Components And Photosynthetic Charcterisstics In Flue-Cured Tobacco

An experiment was conducted during2009to2010with potted flue-cured tobacco YunYan87by controlling irrigation to study the effects of drought stress on the agronomic characters, production quality and physiological features of flue-cured tobacco in jiang xi agricultural university meteorological station to provide the theory foundation about reasonable irrigation,disaster prevention and reduction the losses of flue-cured tobacco in the field. The experimental treatments were set as drought7d,10d,13d,16d, prolonged drought and CK(compare) in three growth periods(rosette stage, vigorous growing stage and budding stage) respectively. The results showed that:1. The plant height, average single leaf area and he biggest single leaf area of flue-cured tobacco would be decreased by the effect of drought stress in rosette stage, vigorous growing stage and budding stage. The short-term drought (7d) impact on the plant height and average single leaf area was not obvious, which the moderate drought (1Od,13d) had great influence on and drought16d had the most influential effect. the stem perimeter, root length, the number of first lateral roots and the volume of roots all increased at first then decreased by the prolong of the drought time in rosette stage, vigorous growing stage and budding stage.2. The total dry matter was downtrend by the influences of drought stress in any period of rosette stage, vigorous growing stage and budding stage. The longer drought time was, the more obviously declined. The proportion of dry matter distribution in the root and stem would increase and decrease in the leaves by the drought stress in each growth period.3. Tobacco production and the content of reducing sugar, total phosphorus and total potassium would be decreased, while the content of total nitrogen and nicotine would be increased by the effects of drought stress in rosette stage, vigorous growing stage and budding stage. The most influential stage to the yield was rosette stage, the least one was budding stage, and which the chemical components was opposite to. The time of drought tolerant of Yuyan87was in half a month, for more than half a month,the yield would reduce nearly a third while total nitrogen and nicotine contents increased twice.4. The net photosynthetic rate (Pn) stomatal conductance (Cond) and transpiration rate (Tr) diurnal changes in every treatment all appeared as single peak curves by the drought stress in rosette stage, and the value were decreased with time.Compared with CK, the daily average and the peak of each index did not decrease significantly by the short-term drought (7d),and which were down obviously under the drought16d. There was no obvious differences between water utilization efficiency and the daily mean of leaves temperature in the treatments. The intercellular CO2concentration was slightly down. Suitable drought could not only improve the water use efficiency of tobacco, but also accelerate the rate of increase in leaf temperature and to a higher leaf temperature, and it had an adverse effect on photosynthesis at rosette stage in flue-cured tobacco. The content of chlorophyll would decrease more obviously with the drought duration.