Vol. XV. Xo. 357. 



THE AGRICULTUKAL NEWS 



13 



PHYSIOLOGICAL EFFECTS ON HEVEA 



BRASILIENSIS PRODUCED BY 



TAPPING. 



Bulletin No. 1:2 of the Department of Agriculture, 

 ■Ceylon, dealt with descriptions of, and yields of rubber pro- 

 duced by, various systems of tapping carried out at the 

 Experiment Station, Peradeniya, during 1911-1-3. The 

 present lUilletin (No. 19) for -July 191-5, is to be regarded as 

 complementary to Bulletin No. 12, and contains the results 

 of the examination of the trees with regard to the relative 

 quantities of reserve food stored in the bark and wood in, 

 and at various distances from, the tapped areas. 



The tapping systems employed are divided into three 

 classes in accordance with the arrangement of Bulletin 

 No. 12, viz.: (1) tapping on one-third circumference; (2) 

 tapping on alternate days versus daily tapping on alternate 

 months; (.3) pricking methods. 



With regard to (1), the e-icperiments were carried out 

 between July 1912 and December 1913 as lollows. 



78 A — Four cuts one foot apart to the left of the 

 channel. Tapping e.xtended over one-third of the tree's 

 circumference and was carried out twice per week. 78 B — 

 Four cuts one foot apart to the left of the channel. Tapping 

 extended over one-third of the tree's circumference and was 

 ■carried out once per week. 81 A — Two cuts one foot apart 

 to the left of the channel. Tapping extended over one-third 

 of the tree's circumference and took place three times per 

 ■week. 81 B — Two cuts two feet apart on one-third of the 

 tree's circumference. Tapping took place three times per 

 ■week. 81 C — One cut at three feet from the grrmnd. The 

 tree was tapped on one-third the circumference six times 

 per week. 82 B - Three cuts one foot apart to the right of 

 the channel and one-third of the tree's circumference- The 

 tree was tapped three times per week. The results are 

 summarized as follows: — 



78 A and 78 B. 'In one case the tree had been tapped 

 twice a week, and the whole of the bark between the top 

 and bottom cuts had finallj' been exci.sed. In the other case 

 tapping had taken place only once a week, and untapped 

 bridges of bark, .")i to 6 inches broad, remained between the 

 tapped areas. 



'In the former case the ert'ect of tapping on the storage 

 of food supplies was very strongly marked, and was apparent 

 in the region below the lowest tapping cut right down to the 

 roots. It was also apparent horizontally, 1 inch to the side 

 of the lowest tapped area. 



'In the case of the tree which had been tapped only once 

 per week, the effects were only local and did not extend to 

 a distance of 3 inches measured vertically below the cut. No 

 effects were detected in the roots. It is thus apparent that 

 the widespread effects observed in the former case were due 

 to a large number of cuts being continued until each tapped 

 area adjoined the next. There is evidence of a small with- 

 drawal of starch horn the bark and wood for a short distance 

 vertically below a single cut. Where there are four cuts, 

 -each of the upper three being continued down to the area 



originally tapped by the cut beneath it, the etj'ect of each on 

 the food storage is apparently felt by the tapping cut bolow 

 It, the effect of which in its turn is thus nuignilied. The 

 etfoct IS thus cumulative, and below the lowest cut a very 

 con.siderable effect is ob.servaltle.' 



■"^1 A. ' The effects of tapping on the food supplies of 

 the tree were absolutely localized. No eft'ect was observable 

 2 inches vertically below, or 1 inch horizontally to the side 

 ot, the tapped area.' 



81 B. 'In this case again the effects of tapping on the 

 food storage of the tree were apparently absolutely localized. 

 No effect was observable at .short distances to the side of, 

 or vertically below, the tapped areas. Halt-way down the 

 tapped areas the bark was commencing again to store up 

 starch, and the wood beliind this baik was also recovering 

 its starch content.' 



81 C. 'The bark at distances of -j, h, and 'I of the 

 length of the tapped area, measured vertically down from 

 the top, showed that the bark contained traces of starch only, 

 but that the wood behind had nearly recovered its normal 

 starch-content. The regions in the immediate neighbourhood 

 of the tapped area, both to the side of and vertically below 

 it, showed no depletion of starch-content, and were similar 

 in condition to sections of the trees taken above the tapped 

 area. The effect of tapping in this respect was, therefore, 

 absolutely localized. 



The results in regard to 82 B. are thus summarized: — 



'There were definite indications that the regions below 

 the tapped area had sutt'ered some small withdrawal of starch 

 from the outer zones of the wood, though the effects were not 

 so pronounced as in the case of 78 A, in which there were 

 four cuts and tapping was to the left. 



'The untapped regions to the side of that vertically 

 below the most recently tapped area also showed evidence of 

 starch depletion in the wood, though this might have been due 

 to the effects of previous tapping in the regions directly above 

 rather than to the obliquely directed effects of the most 

 recent tapping. This, however, would seem to be improbable, 

 as the lack of starch in the sections of wood in question is 

 greater than that in the wood behind the old tapped bark 

 directly above. Some effect, therefore, had in all probability 

 been produced in large jjortions of the tree below the most 

 recently tapped portion.' 



The expei'iments in regard to tapping on alternate days, 

 and pricking methods, with the summary of results and final 

 conclusions drawn therefrom, will ))e given in the next iss^ie 

 of the Agricultural Neirs. 



Grenada Land Settlements.— The monthly report 



by the Agricultural Instructor for October 191.5 has been 

 forwarded from (irenada to this Office by the Governor. In 

 this report mention is made, amongst other matters, of the 

 progress attained in connexion with the experimental plots, 

 llounceval peas have been raised for seed distribution, and 

 the limes and horse beans at St. Cyr Mountain Settlement 

 are making very satisfactory growth. The beans, which were 

 planted on August 20, were ffowering at the end of October. 

 As regards crops on the settlements, it is stated that cacao 

 pickings came in with a rush during the month. Prospects 

 seem to indicate satisfactory pickings to December 31. It is 

 also observed that grape Iruit and oranges were coming to 

 maturity rapidly during the month. As regards the general 

 condition of the holdings, it is reported that there is need for 

 better drainage, and that this is lieing given attention in 

 many instances. 



