Adaptability Study on Eight Hevea brasiliensis Clones Introduced from Abroad in Yunnan
Eight Hevea brasiliensis Clones i.e.PB235,PB260,PB310,PB217,PB255,PR261,IAN873,and RRIM712 were introduced and an adaptability trial was established in Yunnan in 1986.RRIM600 was set as the control.Data collection of 17 years shows only PB217 produced more dry rubber than the control.The average yield is 3.8 kg/tree/year,or 1 360.5 kg/hm2/year,which is 135.7%,or 119.7% of the control.The girths of IAN873 and PB217 are significantly longer than the control on the 25th year,which are 115.3% and 109.4% of RRIM600 respectively.The radiation cold resistance ability of IAN873 is higher than RRIM600,but lower than GT1.PR261 shows the best cold resistance ability.