| The study take field sandbur(Cenchrus pauciflorus)as the research plant,artificial aging with the method of high temperature and high humidity was applied at heteromorphic seeds(M and P)of field sandbur.The germination characteristic,vigor of antioxidant enzymes,content of storage materials and endogenous hormones were measured to explore the mechanism of seed aging at the two heteromorphic seeds of field sandbur.The main results were as follows:1.With the extend of aging time,germination rate and vigor decreased gradually at the heteromorphic seeds,and the average germination rate of M type seeds was47.0 % and 32.3 % higher than that of P seeds.2.Superoxide dismutase(SOD)activity significantly decreased with the increase in aging time.The lowest value was observed at 5d aging treatment during the 5 days of germination,60.8 % and 74.5 % decrease were witnessed at M and P seeds,respectively.Peroxidase(POD)activityshowed an increase trendoverall,but most of treatments showed the lowest value at 4d aging treatment,followed by a recovery at5 d aging treatment.POD activity of M seeds were higher than P seeds.The activity of Catalase(CAT)showed a decreasetrendoverall and arrived the lowest value at 4-5d aging treatments.The lowest CAT activity for M and P seeds were appeared at 5d and4 d aging treatments,respectively,decreased by 22.8 % and 43.8 % when compared to control.Malonaldehyde(MDA)content displayed an increase trend,higher valueswere found at M seeds compared to P seeds.3.The soluble protein content in the heteromorphic seeds of field sandbur decreased with the increase of aging time.The lowest value was recorded at 5d aging treatment,77.1% and 76.0 % decrease were found at M and P seeds,respectively.Soluble sugar concentration showed a decreasing trend overall.M and P seeds showed a minimum value at 4d and 5d aging treatments,respectively,reduced by 32.5% and29.4% for M when compared to control.4.The endogenous hormone content at heteromorphic seeds of field sandburvaried under different aging treatments.With the increase of aging time,Indole-3-acetic acid(IAA)content of the two heteromorphic seeds showed an increase-decrease-increase trend.The highest value of M and P seeds were appeared at 4d and 5d aging treatments,18.7% and 8.7% higher than control.Gibberellin(GA3)content showed an increased trend overall.The highest value was found at 5d aging treatement,4.3% and 13.6% higher than control,respectively.Cytokinin(CTK)content displayed an increase trend first,then creased with the increase in aging time.In control,CTK content was higher at M seeds compared to P seeds,but a opposite phenomenon was found at 5d aging treatment.The content of Jasmonate(JA)also showed an increase and decrease trend overall.The highest value of M and P seeds were found at 4d and 3d aging treatments,respectively,18.2% and 20.0% higher than control.Brassinolide(BR)content showed a continuously increase and decrease trend,2.40% and 11.8 % higher when compared to control.Abscisic acid(ABA)content increased gradually with the increase of aging time and reached a maximum value at5 d aging treatment,44.3 % and 32.7 % higher than control for M and P seeds,respectively. |
