Research On Seed Aging Mechanism And Enhancing Seed Vigor Technology Of Phyllostachys Edulis

Phyllostachys edulis seeds were used to study the aging mechanisms; PEG and GA₃ following the L₉(3⁴) orthogonal layout was used to the aged Phyllostachys edulis seeds of different vigor, selecting the best treatment of enhancing the vigor and investigating the physiological and biochemical indexes after the enhancement of Phyllostachys edulis seeds vigor; Also, the germination physiology was studied primarily. The main results were as follows:With aging time increasing, the germination rate, germination index, vigor index of Phyllostachys edulis seeds decreased quickly at the early days of aging and slowly after; The decreasing degree is different, it is that vigor index is greater than germination index and germination index is greater than germination rate; Because vigor index decreased most quickly, it can reflect the vigor level sensitively.With the aging extent deepening, the relative electrical conductivity of Phyllostachys edulis seeds raised, soluble sugar content increased first and decreased after, MDA content increased, SOD and CAT activity reduced, POD activity reduced quickly firstly and raised slowly after, soluble protein content decreased ,GA₃ and IAA content and GA₃/ABA declined, ABA content increased; Analysis indicated that there is a significant relationship between the above parameters and vigor of Phyllostachys heterocycla seeds; The result of principal components analysis indicate that soluble protein, MDA, CAT, IAA, ABA, SOD, GA₃, GA₃/ABA are main factor to effect Phyllostachys edulis seeds vigor, soluble sugar content, relative electrical conductivity and POD are secondary factor.PEG and GA₃ treatments could improve Phyllostachys edulis seeds vigor of different aging level at proper condition, but the treatment efficiency is different. For medium vigor Phyllostachys edulis seeds, the best PEG treatment is that at 25℃,dip Phyllostachys edulis seeds in 300×103 mg.l^-1 PEG for 24h, the best GA₃ treatment is that at 25℃,dip Phyllostachys edulis seeds in 500 mg.l^-1 GA₃ for 12h,and the difference of the two kind of treatments is not remarkable; For low-medium and low vigor Phyllostachys edulis seeds, the best treatment is that at 25℃,dip Phyllostachys edulis seeds in 500 mg.l^-1 GA₃ for 12h.The effect degree of temperature, time and density to different aging level Phyllostachys edulis seeds vigor is different, but the difference among the three factors is not remarkable;However,the difference of vigor index of Phyllostachys edulis seeds that were treated by different treatment is remarkable; It indicated that selecting suitable treatment is very important for enhancing Phyllostachys edulis seeds vigor.After seed vigor of Phyllostachys edulis was enhanced, the relative electrical conductivity of Phyllostachys edulis seeds declined, SOD, POD and CAT activity raised, MDA content decreased, it indicated that reducing membrane lipid peroxidation, maintaining the integrity of cell membrane is an important factor of enhancing Phyllostachys edulis seeds vigor; Moreover, the internal secretion content in Phyllostachys edulis seeds also changed, GA₃ and IAA content and GA₃/ABA increased, ABA content declined, it indicated that GA₃ and IAA could improve the seed vigor and promote the germination of seed.The MDA content of different aging level Phyllostachys edulis seeds treated by PEG was obviously less than seeds treated by GA₃, soluble protein content, SOD and POD activity was obviously higher, but GA₃ and IAA content and GA₃/ABA was obviously lower than seeds treated by GA₃. It indicated that as a kind of high seeping material, PEG could regulate Phyllostachys edulis seed rate of absorbing water to restore and relief the damnification of membrane, and reduce membrane lipid peroxidation, then enhance seed vigor; GA₃ could regulate the balance of internal secretion in Phyllostachys edulis seeds to enhance seed vigor and promote the germination of seed.During the process of Phyllostachys edulis seeds germination, SOD ,POD and CAT activity was raising all the time, MDA content declined slowly overall, there is a significant relationship among the four indexes; Soluble sugar content increased firstly and decreased after, soluble protein content increased overall.