80 PARA RUBBER. 



September. There is an active vegetative period from .September to 

 February, a short resting period in February, and a floral and foliar 

 condition from February to September. The climate during these 

 months has been dealt with in Chapter II. 



Several writers have associated the yield of latex with atmos- 

 pheric conditions, the general contention being that a low 

 temperature in the Tropics and plenty of moisture were conducive 

 to a copious and more or less continuous exudation of latex. 

 "During hot dry weather the amount of water lost by transpiration 

 from the leaves is very great, and it has been argued that this loss 

 reduces the tension in the cortex and therefore in the latex tubes ; 

 hence the poor flow obtained during such times. 



Dr. Haas, as a result of his experiments in Java, concludes that 

 if the humidity of the soil is great, and if the rains are equally distri- 

 buted, the difference in yield during the year is not great, and he 

 further states that though the best times for tapping, in Java, are at 

 the beginning and the end of the wet season, in wet years it does 

 not matter when the trees are tapped. 



In parts of the F. M. S., where the climatic periodicity is not so 

 strongly marked as in Ceylon and South India, there is said to be 

 but little variation in the yield of rubber during different months. 



" Mr. Larkin , whose estate at Castlewood* I have recently visited, 

 tells me that during the late dry month of March all his trees in one 

 part of the estate shed their leaves simultaneously, and remained 

 bare for a time. He continued to tap during this period, and found 

 no diminution in the amount of latex produced." 



According to the above theory, the yield of latex should be most 

 abundant when the trees are leafless, as they cannot then lose 

 much water by transpiration, and it is of interest to note that the 

 experiments made by Arden in 1902 seem to give support to this 

 view. Arden states that the yield from trees tapped when they 

 were leafless was much greater than that from trees tapped when the 

 leaves were beginning to appear or when in full foliage. In Nicaragua 

 the latex from other rubber trees contains the highest percentage of 

 caoutchouc during the dry season. The possession of abundance 

 of latex during the dry season lends support to the theory of its 

 function as a water store during drought. 



In many parts of the Tropics, however, the leafless period occurs 

 when the dryness and temperature of the air are at the maxi- 

 mum, and the collecting of latex would, during such a time, be 

 limited to the very early part of the day and the evening. The 

 results quoted elsewhere tend to show that the best flow of latex is 

 obtained in Ceylon, when the air and soil are abundantly sup- 

 plied with moisture and when the temperature is comparatively 

 low. A period of drought lasting only seven or twelve days 

 appreciably affects the flow of latex, but though, under such con- 

 ditions, the quantity is reduced, the quality is usually improved. 



H. N. Ridley, Agri. Bull, Straits and F. M. S., May, 1904. 



