Effects Of Temperature On Seed Germinating And Physiological Mechanisms Of Sorghum

In this study,30 sorghum cultivars were selected as experimental materials and cultured in artificial climate box.The germinating traits of 30 sorghum cultivars were screened under different temperatures,including 25?(control),20?,16?and 12?.The correlation between these traits and seed germination capacity was analyzed.Low temperature insensitive cultivar(Chiza 101)and sensitive cultivar(Jiza 127)were used as experimental materials.The changes of protective enzymes and water content,crude fat,soluble protein,total starch and soluble sugar in seeds during germination were determined,and the physiological basis of low temperature tolerance of sorghum cultivars during germination were discussed.The results are as follows:1.Through self-organizing-map cluster analysis,30 sorghum cultivars were divided into five categories according to their temperature sensitivity of the strength at germination stage: the first category,highly temperature sensitive cultivars,including Jiza 127;the second category,temperature sensitive cultivars,including Liaoza 36,Tongza 108,Jinza 31;the third category,medium temperature sensitive cultivars,including Liaonian 3,Liaonuo 11,Liaoza 37 and other six cultivars;the fourth category,temperature-insensitive cultivars;There are 11 cultivars including Jiliang 1,Jiniang 1,3401A/Zao 21 R,and 9 cultivars including Jiliang 2,Jiniang 2 and Liaoza 19,which are extremely insensitive to temperature.2.There were significant differences in grain composition,chromatic aberration and grain weight among 30 sorghum varieties.Correlation analysis showed that relative germination rate was negatively correlated with seed fat content and soluble protein content,positively correlated with total starch content and grain weight,and positively correlated with root fresh weight and chromatic aberration;total starch content was positively correlated with grain weight significantly;tannin and chromatic aberration were highly significant positive correlation.The results showed that the higher the content of fat,protein,total starch and grain weight,the higher the germination rate of sorghum seeds.3.With the decrease of germination temperature,malondialdehyde content,POD,SOD and CAT activity in seedlings of temperature-insensitive variety Chiza 101 and temperature-sensitive variety Jiza 127 increased.The increase of MDA in Jiza 127 seedlings was significantly higher than that in Chiza 101,and the content of MDA in buds was higher than that in roots.The activities of POD,SOD and CAT in Jiza 127 seedlings were significantly lower than those in Chiza 101.The results showed that Chiza 101,a temperature-insensitive cultivar,had a better protection system under adversity conditions,thus ensuring the normal growth of plants.4.When sorghum seeds germinated at lower temperature,the energy consumption of sugar,fat and protein in seeds was slower than that at normal temperature,and the metabolic ability was lower,which indicated that lower temperature inhibited the germination of sorghum seeds.Under lower temperature,extremely insensitive to temperature cultivar had higher relative water absorption,faster fat consumption and starch consumption than highly temperature sensitive cultivars,which indicated that extremely temperature-insensitive cultivars had stronger vigor than highly temperature sensitive cultivars.