The Physiological And Biochemical Changes And RAPD Analysis During The Process Of Aging And Restoring Of Cabbage Seeds

Three kinds of cabbage seeds (Xiyuan4, Xiyuan6, Xiyuan8) were used to study the dynamic changes trend of how the seed vigor was improved by osmoconditioning. First the aged seeds of different vigor were obtained by manual aging, then polythyleneglyool (PEG), mannitol gibberellin (GA₃) and KH₂PO₄ following the L₉(3⁴)orthogonal layout were used to treat the aged seed. From the result of the best medicine treatment, treat combinations which could stand for the seed vigor gradually improved by osmoconditioning were chosen out as study points. Finally physiological and biochemical indexes on each chosen point were mensurated to study how the membrane permeation and anabolism change as the seed vigor being improved. The cabbage seeds by manual aging and PEG treatment were used to analysis DNA amplification polymorphism through RAPD. The results indicated that:1. Under the accelerate aging condition(40℃, RH100%), the germination percentage and the vigor index of cabbage seeds reduced as the aging time increasing. The speed of the seed vigor dropping related to the seed variety (genotype). Medium, lowmedium and low vigor seed could be acquired by different aging days, for Xiyuan 6, aging days were l,2,3days, for Xiyuan4 and Xiyuan8 separate aging days were 3,4,5days.2. All three osmoconditioning medicines of PEG, GA₃ and KH₂PO₄ could enhance the cabbage seed vigor, while PEG and GA₃ performed better than KH₂PO₄. As to the different variety and the different vigor degree of the aged seed, factor C (concentration) in the PEG orthogonal treatment was the key factor to the treat result and factor B (time) in the GA₃ and KH₂PO₄ orthogonal treatment was the determinant of the result. After the aged seed were treated by each best effect medicine combination, the vigor index was extremely significantly higher than that of the CK (untreated seed).3. The mensuration results of physiological and biochemical indexes on each chosen point indicated that: along with the increasing of seed vigor index, the relative conductivity and the MDA content was reducing, the content of protein and soluble sugar were increasing and the SOD, POD and CAT activity were enhancing, the percentage of changes in these indexes significantly correlated with the change percentage of seed vigor index. PEG had the best treat effect to the low vigor seed, because the change scope and change tendency in every index of low vigor seed were the widest and most obvious in all kinds of aged seed. The result of Principal Component Analysis indicated that: The content of soluble sugar and protein and the activity of SOD, CAT and POD were the primary factors that affect the viability of cabbage seed; the content of relative conductivity and MDA were the secondary factor; all these indexes were the reliable factors to study the enhancement process of seed vigor.4. The reactive system of RAPD-PCR which is applied in the damage and restore of cabbage seed genome DNA was established by filtration and optimization. It was found that the damage of cabbage seed's genome DNA during manual aging could randomly happened after the study on RAPD molecule marking of the cabbage seed during aging and the restore of vigor. Followed the aggravation of aging and the special combination spot which Arbitrary-primer lay on genome DNA was damaged, it was manifested that DNA bands by RAPD decreased. But PEG treatment of osmoconditioning had some effect on the restore of damaged DNA of cabbage seed, it was manifested that the DNA bands would appear over again or was same basically to the CK.