Evaluation of Frost Tolerance of Two Acacia Species Introduced from Australian Temperate Zone

Frost tolerance of Acacia melanoxylon and Acacia implexa introduced from the Australian temperate zone was evaluated on basis of conductivity along with multi variety analysis of Australian climatic factors.There was no significant difference for frost tolerance between the two Acacia species,and only slightly stronger frost tolerance of A.implexa was found.However,results showed very significant difference for hardiness among the 17 provenances of two Acacia species.The sensitizing range of low temperature for A.melanoxylon is -4 ℃,and -4～-6 ℃ for A.implexa.Most of provenances from northern areas (Queensland) with further southern latitude of 32°S showed lower frost tolerance with an exception of the seedlot from LAWLERS of NSW.There were 60% of seedlots from cooler areas showing stronger frost tolerance.A.melanoxylon seedlots with stronger hardiness are from RED CR.of TAS,GAMBIER of SA,LAWLERS of NSW and BONANG of VIC,and the A.implexa seedlots from SYDENHAM and PYALONG of VIC,YASS GUNNING of NSW.