RUBBER PLANTING 91 



Summary. 



In Hevea brasiliensis as grown under plantation 

 conditions, repeated tapping on a moderate system at 

 intervals varying from one to ten days leads to an 

 immediate steady increase in the yield of latex and 

 rubber obtained at each tapping. In the case of young 

 and vigorous trees, this increase may continue for an 

 indefinite period, subject to certain seasonal variations. 

 The increase is found to take place even with daily 

 tapping if the system adopted is such as to allow four 

 years for the renewal of the bark. In the case of old 

 trees, closely planted, after tapping has continued for 

 some time, the yield from tapping at longer intervals 

 increases relatively to the yield from tapping at shorter 

 intervals. 



This fact may be regarded as one aspect of the more 

 general phenomenon that moderate tapping leads to 

 a steady increase in yield, whilst overtapping ultimately 

 leads to a relative falling off in yield. The amount of 

 excision which constitutes overtapping depends upon 

 the conditions and upon the individuality of the 

 particular tree. 



The bulk of latex which can be extracted in a year 

 is probably often quite as great as the total volume 

 which all the latex tubes of the tree could contain at 

 any one time. Although the latex can pass gradually 

 from one part of the tree to another, especially in 

 the vertical direction, the greatest part of the latex 



