340 



[June 1907. 



GUMS, RESINS, SAPS, AND EXUDATIONS. 



Experimental Rubber Tapping in Singapore Botanic Gardens. 



By Ivor Etherington. 



As we are at present only in the first stages of rubber cultivation and have 

 been working more or less in the d irk, with but what is really only rudimentary 

 knowledge of the subject, the results of carefully conducted experiments continued 

 over a fair period of time must be regarded as of the greatest importance. Various 

 experiments have been carried out during tlie last few years in Ceylon and Malaya 

 to determine, among other problems confronting the rubber planter, the most satis- 

 factory and economic methods of tapping, and the effect of tapping upon the trees, 

 npon the quality and flow of the latex, and upon the rubber produced. We must 

 give first place in these experiments to the work carried out at the Singapore 

 Botanic Gardens by Messrs. H. N. Ridley and R. Derry, Their experiments, 

 through the length of their duration, the care with which they have been carried 

 out, and the excellence and comprehensiveness of their results, at present hold 

 premier place ; and we must congratulate the Director of the Singapore Gardens 

 on the work initiated by him and carried out under his directions. 



Last year the first annual report on the experiments was of much interest, 

 but this year the results are of far more importance, after a second year's con- 

 tinuous work. 



FRUITING of Heve.a BraftiLienais. 

 Before dealing with the results we will refer to some remarks in the report 

 on the fruit periodicity of the Para rubber tree, which has a bearing on the tapp- 

 ing results. 



"We note that there is a considerable difference between the trees in the 

 Singapore Botanic Gardens and the average mature trees in Ceylon. In the Straits 

 the trees may bear fruit in any month of the year ; although there is a considerable 

 range in the crops and the period of heaviest yield is July — October, with auother 

 heavy yield in the month of March. The following table shows the total number 

 of seeds collected in each month for the past nine years in the Singapore Gardens :— 



January ... 32,924 July ... ... 29,650 



February ... 55,800 August .. ... 79,600 



March ... ... 148,050 September ... 324,515 



April ... ... 56,314 October... ... 291,436 



May ... ... 28,097 November ... 85,870 



June ... ... 28,700 December ... 35,807 



This agrees more or less with Ceylon ; for here we have the main— we may 

 say, the only— fruiting period in the Autumn. The Uva Province is the only dis- 

 trict in Ceylon Avhere we know there is a special Spring fruit period, February- 

 April, corresponding to the Singapore one. But we should be glad to hear from 

 planters in various districts on this point. Variability of seasons seems to affect 

 the fruit yield and the floral activity in the varying seasons. The best crop month 

 in Spring is March, which over a period of 9 years stands third in the annual 

 returns, and varies from nil return in 1905, and only 50 seeds in 1902, to 43,050 seeds 

 in 1901. A similar variation may be observed in the autumn crop for August, which 

 out of a total of 79,600 seeds for 9 completed years produced no less than 60,850 seeds 

 during that month in 1905. 



An interesting tabulation of the two seed crops and the average year's 

 rainfall over 9 years, tends to prove that, (1) while there are two seasons when 

 flowers and fruits may occur in some years within the period of a year, there is 



