Abstract:

Seeds of Juglans nigra L.stored for one year under 0～5 ℃ were adopted in this research to investigate the effect of stratification ways on seed water content, endogenous hormon content, germination and following seedling growth. The period of stratification was highly required by the seeds of J.nigra to make a successived germination and later-on vigor growth. It was slower for the seeds to absorb water during stratification. As reaching saturation water content, the seeds were available to germinate. The higher the seed water content was before stratification, the shorter the time to be used to reach the saturation water content would be. The dormant seed contained lower level of GA₃ and high ABA. As the stratification process, GA₃ showed an obvious increase and ABA a sharp decrease, finally to zero. The rate of GA₃ to ABA might be an inner factor to control the seed germination. Among the stratification ways, the treatment of soaking the seeds in water for 5～6 days and then stratifying them at 2～5?℃ for 120～150 days presented the best and seed germination rate could be achieved as high as 75%. Although moisture absorption pretreatment could retard seed water absorbing, mosture absorption treatments showed no promoting seed germination. The stratification under low temperature had a significant effect to promote seedling growth in the following growing season and the promoting effect was enhanced as the stratification time increasing within a certain extent.

Key words: Julans nigra L., Seed, Stratification, GA₃, ABA, Water content