Comparative Study On Cold Resistance Of Sevral Ilex Tree

Two-year-old cutting seedlings of6types of Ilex (Ilex×'Nellie R.Steven',Ilex. triflora,Ilex.×koehneana 'Emily Bruner',Ilex. mersevae'Blue Gir',Ilex. mersevae'Blue Boy',Ilex.dabieshanensis) as experimental material. Their were exposed to simulated low temperaturestress. Then, we studied the biofilm system,osmolyte,chlorophyll fluorescence parameters andultramicroscopic structure. The major results were summarized as follows:With temperature reducing, the relative electrical conductivity in detached leaf of the Ilexwas"S"increasing curve, the LT50according to the logistic equation, the LT50of Ilex×'NellieR.Steven',Ilex triflora,Ilex×koehneana 'Emily Bruner',Ilex mersevae'Blue Gir',Ilexmersevae'Blue Boy',Ilex dabieshanensis is-12.27℃,-22.5℃,-24.28℃,-11.84℃,-12.63℃and-16.32℃. We also found changes of MDAcontent has no regularity.Activity of POD andSOD of Ilex l. under different cold temperature was different.Under low temperature stress, soluble sugar content of Ilex was ascendant trend; solubleprotein content of Ilex dabieshanensis declined at first, then raised, the other Ilex raisedat first,then declined; the changes of proline content are different, the result of variance analysis showedthat the proline content were no significant differences under the different low-temperaturetreatment, the differences of different species and mutual were significant. With different time ofexposure to-10℃, soluble sugar and soluble protein content declined at first, then raised, prolinecontent basically was ascendant trend.Under low temperature stress, Fv/Fo,Fv/Fm,ΦPSâ…¡ of Ilex basically were declined trend.The qP of Ilex triflora,Ilex×koehneana 'Emily Bruner' declined at first, then raised, the otherIlex Declined. With different time of exposure to-10℃, the changes of Fv/Fo,Fv/Fm of Ilexwere different, ΦPSâ…¡and qP were declining trend.Under0℃cold stress, the damage of ultrastructure of leaf cell of Ilex was small, mostorganelles were kept better, the strueture of mitochondrion was clear, chloroplast were orderlyarranged, osmiphilic granule was less. With the aggravation of the low temperature stress,organelle were damaged gradually, osmiphilic granule increase, the chloroplasts were disorderlyand twisted, and annulate lamellae increased. With the aggravation of the low temperature stress,Ca²⁺transfered gradually and elevation of Ca²⁺level of leaf cell of Ilex.The cold-resistance ability of six Ilex plants, from higher to lower, was Ilex×koehneana'Emily Bruner'＞Ilex triflora＞Ilex dabieshanensis＞Ilex mersevae'Blue Boy'＞Ilex×'NellieR.Steven'＞Ilex mersevae'Blue Gir', by subordinate function values analysis.