| Different varieties or strains of sweet sorghum were treated with differentconcentrations of NaCl solution during germination or seedling growth period in orderto study their salt tolerance, and at the same time to perliminarily screen sweetsorghum varieties (strains). Field experiment in saline-alkali soil was also conductedin order to screen salt-tolerant varieties (strains) to be planted in saline-alkali soil. Theexperimental results were as follows:1. The preliminary screening of the18sweet sorghum varieties (strains)18sweet sorghum varieties (strains) were treated with different concentrations ofNaCl (0%,0.5%,1.0%and1.5%) and the salt tolerance were studied at germinationand seedling growth stage. The results showed that the sensitivity to salinity differedin germination and seedling period in different cultivars. With the increase of salinity,the germination vigor, germination percentage and germination index all decreased,salt injury index were increased; seedling biomass and the actual photochemicalefficiency (ΦPSⅡ) were negatively correlated with salt concentrations, DW/FWincreased and water content reduced accordingly. The results also showed that theseed germination of some sweet sorghum varieties (strains) were inhibited slightlywhile other varieties were promoted under low concentration of NaCl (0.5%). Underhigh salinity stress, however, except for a few special varieties (strains) which wereless inhibited, most of the varieties (strains) were severely inhibited, with thegermination time delayed, the indexes such as germination vigor and germinationpercentage decreased markedly. In seedling stage, the biomass and ΦPSⅡ of everyvariety (strain) declined with the increase of salt concentration, even under low saltconcentration. Each index declined significantly than that of control. When theconcentration of NaCl reached1.5%, sweet sorghum varieties (strains) were severelyinjured, and were on the edge of death after three weeks of treatment. Comprehensing the salt tolerance indexes of germination and seedling period obtained, L1, N1, SMK,H and some other varieties (strains) showed worse salt tolerance, we selected one ofthem (L1) as control in the following screening experiment. JZ1, JZ5, JZ10and suchother varieties (strains) showed stronger salt tolerance.2. Further screening of the7sweet sorghum varieties (strains) from the preliminaryselectionCombining with the results from the above experiment,7kinds of sweetsorghum varieties (strains): L1, J1, JZ1, JZ3, JZ5, JZ8and JZ10were picked out asthe experimental materials and treated with different concentrations of NaCl (0%,0.3%,0.6%and0.9%) at seeding stage and seedling growth stage. The results showedthat with the increase of the concentration of NaCl, the germination potential,germination percentage, germination index, bud length, root length and coleoptilelength declined. Seeding biomass, photosynthesis and photosynthetic related indexeswere negatively correlated with salt concentration. Ion content in plant was positivelycorrelated with salt concentration. Considering all the indices above, JZ1, JZ5andJZ10showed higher salt tolerance than the others.At the same time, the7kinds of sweet sorghum varieties (strains) were selectedin Dongying saline-alkali soil experimental field for salt tolerance identification test,the experiment showed that the yield of JZ10was the highest, while L1was thelowest, though the experimental plots area was quite large, and salinity distributionwas extremely far from uniform, which caused the test results showed certaindeviation, but some of the results can be used as reference.The yields of varieties wererelated to the salinity distribution in the field.The analysis results showed that JZ1, JZ5and JZ10showed stronger salttolerance. Taking the economic costs and yield into account in the saline-alkali soil, itis more appropriate to choose these three kinds of sweet sorghum varieties to plant infield. |
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