Study On The Substance Changes And Their Relationship With Dormancy Broken Of M. Sieboldiik. Koch Seeds During Stratification

M.sieboldii k.koch'seed was studied in this paper, M.sieboldii k.koch'seed with different concentrations of Gibberellic acid solution(500,1000,1500 mg·L-1) and clean water was soaked for 48h,then to deal with variable-temperature stratification treatment:low temperature stratification (0-5℃,30d),variable-temperature stratification between day and night (8-10℃, night-5-0℃,60d),alternating variable-temperature stratification (high 12-14℃, low0-5℃, change temperature every 5 days,60d).By means of observing embryo growth and measuring storage substance contents,sucrose-metabolizing enzymes activities,endogenous hormones contents,to understand the relarionship between embryo growth,metabolic transformation of materials and seed germination, especially the controllable actions of endogeneous hormones contents and seeds bourgeon. To further reveal the mechanism of seed dormancy. Main reasults of this study were as follows:1. The embryo development of M.sieboldiik.koch'seed after harvesting was not mature,which was one of the main causes of seed dormancy. Seed embryo continuously differentiateand developduring the whole stratificationprocess,the embryo growth of different GA3 treatment were superior to CK treatment,and GA3 treatment could stimulated morphological maturation of seeds before 30 days.2. Soaken by GA3 and controlled variable-temperature stratification had a better seed germination effects, seed germination rate gradually increased with GA3 concentration improvement and extension of stratification time. The best germination rate appearred in stratification 120-150days,GA31000-500 mg·L-1,the germination rate of GA31500 mg-L-1 treatment was up to 70%.Different concentrations of GA3 could inhibite the growth of M.sieboldii k.koch seedlings.Based on M.sieboldii kkoch seeds development and seedling growth, GA31000 mg-L-1 treatment could effectively break the M.sieboldii k.koch seed dormancy,promote seed germination and seedling growth.3. Storage substances rapidly changed during variable-temperature stratification process on GA3 induced, starch as a temporary substance was decomposed continuously, soluble sugar content also continued to decline, soluble protein content was accumulated in the initial and laminated, and significantly reduced in the follow. Storage of material showed decreasing trend in general.4. M.sieboldii kkoch seeds contained a large number of sucrose content before stratification, and sucrose content changed more rapidly than glucose and fructose content. On GA3 induced sucrose were predominantly accumulated in the early stratification(40 days)and late stratification (120 days), at the same time the activities of sucrose synthase (SS)and sucrose phosphate synthase(SPS) rised;the acid invertase (AI) and neutral invertase activity (NI) reduced; The glucose and fructose increased,in the medium (90 day).Glucose and fructose content had the incresing thrend with the increasing amount of GA3, the value of glucose and fructose on 1500mg·L-1 GA3 was 0.33 mg·g-1and 0.38 mg-g-1 respectively. Meanwhile, the activity of AI and NI reached the maximum,while the activities of SS and SPS reduced.Changes of sugar content were controlled by a variety of enzymes, the AI and NI dominated sucrose hydrolysis, accumulation of sucrose was affected by SPS, but the action of SS was weak. Activity of enzymes in sucrose metabolism was primarily determined by activity of enzymes on sucrose cleavage, It meaned that AI and NI were playied the main regulative role in the M.sieboldii kkoch seeds sugar metabolism.5. Changes of endogenous hormone content in testa of M.sieboldii kkoch seeds on different treatments:GA3 content fluctuated in 100ng.g-1FW within stratification 90 days,then gradually rised; IAA and ABA content declined precipitously with the continuous extension of stratification time; ZR content changes little within stratification 70 days,then increased gradually, ZR content of GA31500 mg·L-1 treatment reached the maxim in stratification 120 days.6. Changes of endogenous hormone content in endosperm of M.sieboldii kkoch seeds on different treatments:Hormone endosperm content in endosperm was significantly higher than in testa, GA3 content in endosperm kept upward trend,with GA31000,1500 mg-L-1 treatment maintained on a high level; ABA content declined continuously, ABA content of CK treatment decreased slowly; IAA content was significantly increased in stratification 40 days,then continued to fall; ZR content sharply reduced in stratification 40 days,then increased gradually, ZR content of GA31500 mg-L"1 treatment came to maximum.7. changes of endogenous hormone ratio during stratification process on different treatments: The ratiof GA3/ABA, ZR/ABA, IAA/ABA was closely related to the lifting of seed dormancy,changes of these ratio were stable before the stratification 90 days,then gradually increased. Changes of GA3/ABA,ZR/ABA ratio in endosperm were correlative with seed dormancy process, IAA/ABA was closely related to enbryo development, while changes of GA3/ABA in testa were correlative with seed dormancy process. Finally, it was proposed that variable-temperature stratification treatment result in dormancy release of M.sieboldii k.koch seeds probably through regulating the changes of endogenous hormone content and the balance of endogenous hormone content existed in the seeds.