Effects of Calcium on Polyamines Contents and Polyamines Oxidase Activity of Cucumber Seedlings with Hypoxia Stress

The experiment was conducted to study the effects of calcium on polyamines(PAs) contents and polyamine oxidase(PAO) activity in 'Zhongnong 8' cucumber seedlings under hypoxia stress in hydroponics.The results showed that:(1) the contents of PAs,putrecine(Put),spermidine(Spd) and spermine(Spm) with free,conjugated or bound forms in cucumber seedlings leaves and roots ranked as below,the treatment with hypoxia stress and higher Ca2+ treatment(8 mmol·L-1 Ca2+) was first,the one under hypoxia stress with 2 mmol·L1 Ca2+ followed,hypoxia without calcium one(0 mmol·L-1 Ca2+) was the third and one with 2 mmol·L-1 Ca2+ was the lowest.At the mean time,PAO activity of above treatments appeared as reserved order,the aeration plant was the highest,hypoxia without calcium one followed,the one with hypoxia stress and 2 mmol·L-1 Ca2+ was the third and the one under hypoxia stress with higher Ca2+ was the lowest;(2)The highest contents of three forms of PAs was free PAs,the second was conjugated PAs,the third was bound PAs.These indicated that calcium application increased the content of PAs and decreased the activities of PAO,calcium involved in the process of PAs metabolism and played an important role in alleviating the injury of cucumber seedlings with hypoxia stress.