Physiological response and cold-resistance evaluation of Euscaphis japonica and Euscaphis konishii under low temperature stress

【Objective】 To evaluate cold resistance of Euscaphis japonica and Euscaphis konishii，so as to provide scientific basis for breeding cold-resistant Euscaphis.【Method】Seedling shoots of E.japonica and E.konishii sprouted that year were taken as materials to be treated with 4℃ for 0，5，10 and 15 d，and the contents of soluble protein（Pro），soluble sugar（SP）and malondialdehyde（MDA）in the fixed leaves were picked and measured，catalase（CAT），peroxidase （POD），superoxide dismutase（SOD）activities，and relative conductivity（REC）were measured.Principal component analysis and membership function method were used to screen cold-resistant E.japonica and E.konishii according to physiological and biochemical indexes and evaluate cold resistance of E.japonica and E.konishii.【Result】POD，CAT and SOD activity of leaves of E.japonica and E.konishii under low temperature stress rose first and then fell.The change range of SP content of E.japonica leaves was smaller than that of E.konishii leaves.Pro contents of E.konishii and E.japonica leaves first increased and then decreased，but Pro contents of E.japonica leaves did not decrease significantly in the later stage（after 5 d）.MDA content and its change range of E.konishii leaves were higher than that of E.japonica leaves.REC of leaves of both varieties increased with the extension of low temperature treatment time.Except significant correlation was found between MDA content and SP content（P<0.05），no significant correlation among the other indexes was found（P>0.05）.The importance of physiological and biochemical indexes for distinguishing cold resistance of E.japonica and E.konishii was in the order of POD=REC>Pro>MDA>SP>CAT.【Conclusion】 POD，REC，Pro and MDA can be used for cold-resistance breeding and screening cold-resistant E.japonica and E.konishii.Among them，POD and REC have a greater impact on the cold resistance of the two tree varieties.In addition，the cold resistance of E.japonica is much stronger than that of E.konishii.E.japonica can be taken as the rootstock to graft E.konishii to improve the cold resistance of E.konishii.