Study On Difference Of Tolerance To Waterlogging Among Vavieties Of Tobacco And Their Mechanisms

Effect of waterlogging at different growth stages and different days on morphological, physiological,biochemical indexes and quality of tobacco were discussed in the experiment; waterlogging tolerance among five kinds of tobaccos was identified in the experiment,too. The results were as follows:1.Effect of waterlogging at different growth stages on tobacco growthThe influence of waterlogging stress at different growth stages on flue-cured tobacco growth were studied under pot experiment by use of cultivar k326 as the experimental materials.The results showed that:under waterlogging stress,content of photosynthetic pigment decreased,contents of malondialdehyde(MDA),activity of superoxide dismutase (SOD) and free proline(Pro) increased,activity of root decreased.Meanwhile,effects of waterlogging stress at rosette stages and vigorously growing stages were the greatest.The root volume and dry matter quantity were inhibited to different extents,adventitious root quantity and dry matter quantity increased remarkably compared to the control.Viewed RIR value of the injured characteristics,effects of waterlogging stress at resettling stages and vigorous growing stages were the greatest.For all the groups at different growth stages, contents of nicotinic and K uptake decreased,content of nitrogen increased,but content of chloride presented the irregular changes.Total soluble sugar,reducing sugar and starches in the harvested flue-cured tobacco leaves decreased because flooding stress seriously affected the photosynthesis of tobacco.Viewed RIR value of chemical constituents,influence of waterlogging at vigorous growing stages and mature stages on tobacco quality was the most.2.Effect of waterlogging at different days on tobacco growthInfluence of waterlogging stress at different days on growth of flue-cured tobacco was studied under pot experiment by use of cultivar k326 as the experimental materials during the vigorously growing period.The results showed that:(1) Morphological indexes such as the stem,stem girth,leaf dry weight and root dry weight in the flue-cured tobacco tended to decrease with the time prolongation of waterlogging.(2) Physiological and biochemical indexes among flue-cured tobacco leaves presented variable changing rules with the time prolongation of waterlogging,chlorophyll content,transpiration rate(Tr),net photosynthetic rate,free proline content,activity of soluable protein and root tend to be lower,stomatal resistance gradually increased at earlier period(on day 8 after waterlogging treatment),and then gradually decreased.However,malondial-dehyde(MDA) content,superoxide-dismutase (SOD) activity and soluble sugar content in the flue-cured tobacco leaves ascended gradually during the earlier period(on day 6 after waterlogging) and then descend gradually during the later period.(3) Chemical quality index'es such as K,nicotine and soluble sugar content in the harvested flue-cured tobacco leaves decreased gradually with time prolongation of waterlogging;Total N content was on rise gradually during the earlier period (on day 6 after waterlogging) and after that it decreased rapidly with time prolongation of waterlogging.3.lndentification of waterlogging stress on breeding of flue-cured tobaccoUnder the pot experiment,some physiological,biochemical and morphological indexes such as biomass,photo-synthesis rate,transpiration-rate,soluble protein,soluble sugar and root activity related to waterlogging-stress in 5 different kinds of tobacco cultivars were investigated by artifical flooding treatment,which was instead of waterlloging conditions.A comprehensive evaluation of waterlogging stress was carried out through analyzing subordinate function value by way of combining multiple indexes(including physiological, biochemical,and morphological indexes).The results showed that there was difference in the sensitivity and tolerance to the waterlogging stress for the different kinds of tobacco breeding even if they were under the same waterlogging conditions.In the 5 different kinds of tobacco cultivars,G80 was a type of waterlogging stress,K326 and Yunyan85 were intermidiate types whereas NC82 and Honghuadajinyuan were sensitive types.