Response Of Activated Oxygen Metabolism To Drought Stress Of Four Ornamental Species

Four ornamental species were planted in pots as the experimental material. They respectively are:Photinia serrulata Lindl, Buxus sinica (Rehd. et Wils.) Cheng var. parvifolia M.Cheng, Ligustrum×vicaryi Hort. And Euonymus japonicus Thunb. Natural drought-rehydration treatment was carried outin greenhouses. Physiological indicators of plants under draught stress and nature watering weredetermined, such as superoxide anion production rate, the content of hydrogen peroxide (H2O2),malondialdehyde (MDA) and soluble protein, activities of superoxide dismutase (SOD), peroxidase(POD), hydrogen peroxide enzyme (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR).ascorbic acid-glutathione circulatory system in DHA, ASA, GSH and GSSG content were alsoanalyzed. We want to explore active oxygen metabolism of the four ornamental species to drought stressresponse.On drought stress,the results as follows：Hydrogen peroxide (H2O2) content of all the four species showed increased and then decreasedtrend overall. Superoxide anion production rate of P. serrulata firstly declined the increased,maintaining a high level in all; B. sinica var. parvifolia, Ligustrum×vicaryi and E. japonicus showed adecline after rising at first.As to Malondialdehyde (MDA) content, P. serrulata under drought stress is much higher thancontrol, with little changes. B. sinica var. parvifolia showed upward trend. A middle clump was found inLigustrum×vicaryi. E. japonicus showed a complex trend. P. serrulata and B. sinica var. parvifoliadeclined in soluble protein content. Ligustrum×vicaryi declined after shortly increased, while the trendof E. japonicus was just the opposite.SOD activity of four species activity generally increased and then decreased. APX activity of B.sinica var. parvifolia showed overall upward trend. P. serrulata and Ligustrum×vicaryi decreased afterfirstly increased, while E. japonicus was just the opposite. POD activity of P. serrulata firstly increasedthen decreased. Upward trend was found in B. sinica var. parvifolia. Ligustrum×vicaryi increased aftershortly declined, while the trend of E. japonicus was just the opposite. CAT activity of P. serrulata,Ligustrum×vicaryi and E. japonicus showed increasing trends overall with slightly decreased in themiddle, while B. sinica var. parvifolia show the opposite trend. GR activity of Ligustrum×vicaryi andE. japonicus showed repeated trends with declined after increased. returning to control level afterrewatering. B. sinica var. parvifolia show the opposite trend, still higher than that of control. Declinedtrend with a clumping increase in the middle was found in P. serrulata, declining fast after rewatering.Total ascorbic acid content of overall showed a trend of decreasing after increased with addition t E.japonicus. No consistent changes of glutathione content were found in four ornamental species.A subordinate function was used to rank their drought tolerance and the order was: B. sinica var.parvifolia＞Ligustrum×vicaryi＞E. japonicus.＞P. serrulata. MDA and soluble protein content werethe key indicators to evaluate the drought resistance of the four ornamental species.