Effects of Brassinosteroids on the Chilling Resistance of Dendrobium huoshanense
In order to study the effects of different concentrations of BR on the chilling resistance of Dendrobium huoshanense,we carried out this experiment with annual stems and leaves of biennial D.huoshanense.D.huoshanense plants were sprayed by 0,0.01,0.05,0.10,0.50 mg· L-1 BR,respectively,then suffered chilling stress [day/night temperature were (4± 1) ℃/(2± 1) ℃,respectively] for 48 h.The changes of chlorophyll content,autioxidant enzyme activities,MDA content,relative conductivity,proline content in leaves and soluble sugar content in the stems of D.huoshanense seedlings were determined.The results showed that:(1)Under chilling stress,chlorophyll content was decreased constantly.The activity change trends of SOD,POD and CAT all showed unimodal curve and the peaks were all at the 10th day after chilling stress,MDA content and relative conductivity were both increased constantly in leaves.(2)Pretreatment of leaf spraying BR significantly alleviated the hurts of chilling stress on D.huoshanense,significantly improved chlorophyll content,activities of SOD,POD and CAT,significantly reduced MDA content,relative conductivity in leaves and significantly improved proline content in leaves and soluble sugar content in the stems.(3)The effects of the treatment with BR concentration 0.10 mg · L-1 were significantly better than those of other treatments.So,BR could effectively relieve the peroxide damage to D.huoshanense plant caused by chilling stress,improve its chlorophyll content in leaves,enhance its chilling resistance by improving autioxidant enzyme activities in leaves and their osmotic adjustment ability under chilling stress and BR concentration of 0.10 mg · L-1 was recommended.
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