| In this thesis,experiments under both lab and field were conducted to study the physiological effects and technical index of priming and drying treatment and chemical regulating technology and physiological basis of enhancement of chilling-tolerance during tobacoo germination period． The result showed that: 1,The tobacco seeds were treated by priming and drying．The result showed that the highest germination ratio of seed was of the seed by priming 72 hour and drying treatment． Its germination ratio reached to 93% when the seed bourgeoned to 48 hours and the was earlier 72 hours than contrast．From the microtome the albuminous cells became thin because they were consumed and the radicle grew out the seed coat when the tobacco seeds were treated for 72 hours．And from the exterior of the drying seeds the white radicle can be seen in this period． With the Time of seed bourgeon , there was a yellow dot can be seen on the radicle of tobacco seeds and this yellow dot would become clear and wither and the germination ratio decreased．Probably the seed growing dot was damaged because of excessive priming and the yellow dot be necrosis dot． So the best closing date of priming and drying treatment on tobacco seeds was 72 h after priming． 2,In the second germination progress after priming and drying treatment,the content change of protein,soluble protein and starch which was used balanced in the process of seed bourgeon was stabler and the content of free amino acid and soluble sugar in seed which benefit seed bourgeon and improve seed vitality was higher than that in the contrast seed． 3,Tobacco seeds were treated by three different chemical substances．The result showed:The tobacco seeds were treated by three substances all can resist chilling．From effects on chilling-tolerance,the best concentration of soaking seeds of three substances was different．The most suitable time of soaking seeds about three substances to resist chilling was 48 hours．The substance had a striking chilling-tolerance effect was SA(concentration: 0.5 mmol·L-1；treating time:48 h) and the effect reached to marked difference compared with CK．4,Compared with seedlings who seeds treated by water,the activities of POD,CAT and SOD in seedling who seeds treated by SA (0.5 mmol·L-1)were higher and the content of MDA was lower but not striking different．However,compared with the CK,the activities of POD,CAT and SOD in SA treatment were higher and the content of MDA was lower after chilling-stressed 3 d and reached to a striking difference．This indicated that enhancement of the chilling tolerance of tobacco seedling by SA was probably from enhancing activities of protective enzymes during chilling stress．5,The priming and drying tobacco pelleted seeds were treated by SA． In lab,when the germination rate of treated seeds reached to 80% after sowed 6 d,the CK began to germinate．In field,tobacco seedlings grew better than CK． This indicated that SA and priming and drying treatment could improve tobacco seedling chilling tolerance and pick up the seed germination speed．...
|
PDF Full Text Request