Study On Mechanism Of Improving Vigor In Tomato Seeds By Osmoconditioning

Three kinds of tomato seeds (Hongboshi> Ebide,Hezuo918) were used to study the mechanism of how the seed vigor was improved by osmoconditioning. First the different aged seeds were obtained by accelerate aging, then polythyleneglyool (PEG), mannitol gibberellin (GA₃) > KH₂PO₄ following the L₉ (3⁴) orthogonal layout was 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 changes as the seed vigor being improved. The results indicated that:1. Under the accelerate aging condition (40℃,RH100%) , the germination percentage and the vigor index of tomato seeds reduced as the aging time increasing. Dropped speed of the seed vigor related to the seed variety (genotype). Medium, lowmedium and low vigor seed could be acquired by different aging days, for Hongboshi, aging days were 10, 14, 16 days, for Ebide ,Hezuo918, aging days were 14, 16, 17 days.2. PEG,GA₃,KH₂PO₄, all this three osmoconditioning medicines could enhance the tomato seed vigor, PEG and GA₃ performed better than KH₂PO₄, As to the different variety and the different vigor degree of the aged seed, in the PEG orthogonal treatment factor C (concentration) as the key factor deciding the treat result; in the GA₃, KH₂PO₄ orthogonal treatment factor B (time) was the determinant of the result. After the aged seed were treated by each best effect medicine combination, the vigor index is extremely significantly higher than that of the CK (untreated seed).3. The mensuration result of physiological and biochemical indexes on each chosen point indicated that: along with the increasing of seed vigor index, the MDA content was reducing, the content of protein and soluble sugar were increasing and the dehydrogenase,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 was the widest and most obvious in all kind of aged seed. The change tendency of relative conductivity in each selection was not obvious; PEG treat concentration had the significant influence to the conductivity...