| Experiment was conducted with two different waterlogging-tolerant genotypes of sesame[waterlogging-tolerant genotype Henan1 and nonwaterlogging-tolerant genotype Jizhi1 ] subjected to artificial waterlogging treatment by the design of two-factor random splitted-blocks.Growth rate, Chlorophyll content of leaf, special leaf weight,root vigor, permeability of plasmas membrane and contents of MDA, activities of SOD,POD and CAT, the contents of proline,soluble sugar ,free amino acid and the ratio of free water /bound water were determinated under waterlogging stress with two different waterlogging-tolerant genotypes of sesame,pod number per plant, grain number per pod ,1000-grain weight per plant, yield per plant were tested.Results showed that1.Effects of waterlogging stress on growth rate, Chlorophyll content of leaf, special leaf weight and root vigor were studied with two different waterlogging -tolerant genotypes flooded respectively at seedling stage, initial flowering stage, full blooming stage and final flowering for 48h. The result showed that all of them of the waterlogging treatment was lower than that of control, waterlogging treatment reached extreme significant level﹙P<0.01﹚as compared with the control after initial flowering waterlogging or full blooming.Rate of relative victim was highest after full blooming flooding. Rate of relative victim of growth rate, Chlorophyll content of leaf, special leaf weight and root vigor was respcticely 44.49 percent,41.62 percent,36.04 percent,35.28 percent with waterlogging -tolerant genotypes,that was respcticely 51.2 percent,53.93 percent,43.27 percent,41.78 percent with nonwaterlogging -tolerant genotypes. Rate of relative victim of waterlogging -tolerant genotypes was higher than non waterlogging -tolerant genotypes.Pod number per plant, grain number per pod and 1000-grain weight per plant of sesame were suffered different influences after waterlogging stress,so sesame production decreased. Waterlogging stress had obvious effects on sesame after flooding at full blooming stage, pod number per plant, grain number per pod and 1000-grain weight per plant of waterlogging -tolerant genotype were respectively 80.69 percent,80.28 percent and 86.47 percent of the control.Unfulfilled grain percentage reached 25.9 percent.Yield per plant was 55.98 percent of the control.That of non waterlogging -tolerant genotype were respectively 70.05 percent,71.95 percent and 79.38 percent of the control.Unfulfilled grain percentage reached 33.2 percent.Yield per plant was 40.01 percent of the control. Waterlogging stress had greater effects on sesame after flooding at initial flowering stage or final flowering. Yield per plant of waterlogging -tolerant genotypes was respectively 60.79 percent and 76.99 percent of the control after flooding at initial flowering stage or final flowering,but that of non waterlogging -tolerant genotypes was respectively57.83 percent and 71.13 percent.Under the same waterlogging strength, waterlogging stress had less influence at seedling stage.The sensitivity of sesame to waterlogging stress in different growing periods is full blooming> initial flowering > final flowering> seedling, the sensitivity of different genotypes of sesame to waterlogging stress is non waterlogging -tolerant genotype >waterlogging -tolerant genotype.2.With waterlogging time prolonging at full blooming, special leaf weight, Chlorophyll content of leaves and root vigor gradually decreased.That decreasd extreme significant as compared with the control﹙P<0.01﹚after flooding at full blooming for 72h. Rate of relative victim of special leaf weight, Chlorophyll content of leave and root vigor of waterlogging -tolerant genotype was respectively 41.5 percent,48.78 percent,41.78 percent after floooding for 72h at full blooming stage,That of non waterlogging -tolerant genotype was 56.18 percent,58.68 percent,51.76 percent. Rate of relative victim of waterlogging -tolerant genotype was higher than non waterlogging -tolerant genotype.With waterlogging time prolonging at full blooming, pod number per plant, grain number per pod and 1000-grain weight per plant of waterlogging treatment decreased significantly as compared with the control,so yield per plant decreased significantly as compared with the control.And with waterlogging time prolonging at full blooming,decline range increased. Sesame was sensitive to waterlogging stress at full blooming.Sesame yield decline was critical after waterlogging stress at full blooming.Yield per plant of waterlogging -tolerant genotype respectively dropped to 78.9 percent,67.9 percent and 44.0 percent of the control after waterlogging 24h,48h and 72h.That of non waterlogging -tolerant genotype respectively dropped to74.9 percent,62.7 percent and 33.4 percent.With waterlogging time prolonging at full blooming,the physiological characeristics and yield traits sharply decreased,the sensitivity of different genotypes of sesame to waterlogging stress at full blooming is non waterlogging -tolerant genotype >waterlogging -tolerant genotype.3.With the strength of waterlogging–stress at full blooming,permeability of plasmas membrane and contents of MDA increased gradually,and activities of SOD,POD and CAT rose at first and decreased later. The cell membrane relative eLectric conductivities of Leaves of Henan 1 was 53.16 percent at 72h after flooding ,but that of control was 19.54 percent. The cell membrane relative eLectric conductivities of Leaves of Jizhi 1 was 71.45 percent at 72h after flooding ,but that of control was 21.87 percent.The MDA content of leaves of Henan 1 was 152nmol/g at 72h after flooding ,but that of control was 96nmol/g. The MDA content of leaves of Jizhi 1 was 172nmol/g at 72h after flooding ,but that of control was 102nmol/g.With the strength of waterlogging -stress,the activity of SOD of leaves increased at first and then decreased subsequently and reached its peak at 24h after flooding. The activity of SOD of leaves of Henan 1 was 48.1 percent more than that of control and Jizhi 1 was 40.7 percent more than that of control.But then the activity of SOD of leaves decreased sharply, the activity of SOD of leaves of Henan 1 was 19.8 percent lower than that of control and Jizhi 1 was 36.8 percent lower than that of control at 72h after flooding.With the strength of waterlogging -stress,the activity of CAT of leaves increased at first and then decreased subsequently and reached its peak at 36h after flooding. The activity of CAT of leaves of Henan 1 was 59.1 percent more than that of control and Jizhi 1 was 41.7 percent more than that of control. But then the activity of CAT of leaves decreased sharply, the activity of CAT of leaves of Henan 1 was 16.7 percent lower than that of control and Jizhi 1 was 32.1 percent lower than that of control at 72h after flooding.With the strength of waterlogging -stress,the activity of POD of leaves increased at first and then decreased subsequently . The activity of POD of leaves of Henan 1 reached its peak at36h after flooding and it was 34.1 percent more than that of control.However, The activity of POD of leaves of Jizhi 1 reached its peak at 48h after flooding and it was 41.8 percent more than that of control.And then the activity of POD of leaves decreased slowly, it mainained higher level at 72h after flooding.The activity of POD of leaves of Jizhi 1 was 5.7 percent more than that of control and that of Henan 1 was 20.4 percent more than that of control.Much lower rate of permeability of plasma membrane and malondialdephyde[MAD]content were appeared in waterlogging -tolerant genotype than those in waterlogging -sensitive genotypes under waterlogging - stress. And the waterlogging -tolerant one had higher SOD,CAT and POD activities.4.The changes of organic ompounds contents of different genetic seasame leaves after waterlogging was studied.The results showed that under waterlogging stress,the contents of proline,soluble sugar ,free amino acid increased for several days and then decreased . The ratio of free water /bound water delined as the development of waterlogging.The contents of organic compounds of Henan No.1 were higher than Jizhi No.1.
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