Abstract: The dynamic changes of RR ( resp iratory rate) , SPC ( soluble p rotein content) , SSC ( sol
uble sugar content) , SOD, POD, endohormone IAA and ABA in different parts of three onion varieties ( in
cluding early2maturing, middle2maturing and late maturing types) with differentmaturities during the dorman
cy stage were studied. The results suggested that the length of physiological dormancywas different among the
three varieties, the dormancy period of the late2maturing variety Gangcong 841 was the longest ( about 70 d)
and the early2maturing variety Yangchunhuang was the shortest ( about 40 d). The resp iratory rate, SPC and
the activity of SOD, POD showed a rap id rising trend and then falling trend before the end of physiological dor
mancy. The SSC decreased rap idly after physiological dormancy. The content ofABA was highest in the early
dormancy period, afterwards, a rap id falling until the end of physiological dormancy. Change of IAA was
rightly reverse to ABA. The distribution of these physiological and biochemical data were interior scales >mid
dle scales > exterior scales. It is concluded that the higherABA, lower IAA, SPC and higher SSC are benefi
cial to remain dormancy after harvest.

Key words: Onion, Physiological and biochemical, Dormancy