480 



EDIBLE PRODUCTS, 



[Dec. 1906. 



Cacao Cultivation in Ceylon. V. 



By Herbert Wright. 

 (Illustrated.) 



PERIODICITY OF THE CACAO TREE. 



It is necessary to consider the periodicity of the vegetative and reproductive 

 systems of the cacao tree before dealing with the subject of its cultivation 

 and the harvesting of the crop. There are reasons for believing that the most 

 successful results in cultivation will probably be obtained by taking advantage of 

 the normal periods of varying activity which characterise the different stages 

 in the life of the tree rather than by the application of methods or substances to 

 stimulate parts of the tree during their periods of minimum activity. 



The cacao trees on a large area produce leaves, roots, flowers, and fruits 

 throughout every month of the year, and many cultivators have adopted methods 

 with the idea of making the trees more productive at periods of the year which do 

 not agree with those of the natural periodicities. It is possible, by affecting the 

 water supply to the roots and by the pruning of branches and roots, to considerably 

 change the periodicity of vegetative and sexual tissues, but it is a course which, if 

 not carried out very carefully, may be accompanied by a serious reduction in the 

 cacao crop. 



FOLIAR AND ROOT PERIODICITY. 



In all tropical areas heat and light are intense, and these, together with the 

 heavy rainfall of many places, result in a conspicuous growth of vegetation at most 

 times of the year. Though the climatic changes are not analagous to the seasons of 

 a temperate zone, the plants in the tropics are just as subject to periodical changes 

 of rest and activity as those of cooler zones. The periodicities of the climates in 

 cacao-growing countries differ considerably, and the remarks here given have 

 reference mainly to the cacao trees in the Peradeniya district of Ceylon ; a change in 

 climatic periodicity is usually followed by one of plant periodicity. 



The leaves of the cacao tree show an increase in number year by year until 

 by about the eighth or tenth year a standard size appears to be attained. Through- 

 out these first years the foliar production is irregular, but as time goes on there i s 

 a tendency to produce a large number of new leaves during two or three periods 

 each year. On a cacao estate with all the trees in bearing it is impossible to find 

 a healthy specimen absolutely leafless even during the hottest and driest part of 

 the year ; most of the trees produce a few leaves every month in the year, 

 but reserve their periods of maxima foliar production for the months of February, 

 March, and September, considerations to be kept in mind when dealing with the 

 periodicity of the flowers and manurial operation. The periodicity in the root 

 growth of cacao trees in Ceylon is but little understood ; the rootlets are formed 

 during every month in the year, but during ApriKTune and again in October. 

 November there appears to be increased activity in this part of the plant. The 

 general observations made on this part of the subject point to a periodicity of 

 root activity in association with that of the foliage. 



FLOWER PERIODICITY IN 1903. 



An investigation has been made on the periodicity of flower production 

 with a view of determining its relationship to that of the fruits and rainfall. Forty- 

 two trees were under observation each day in the years 1903, 1901 and 1905. The 

 flowers were plucked after they had opened, so that the physiology of the plant 



