2 



[July, 1911. 



GUMS, RESINS, SAPS AND EXUDATIONS. 



THE GERMINATION OP HEVEA 

 SEEDS. 



(Prom the Agricultural News, Vol. X. 

 No. 233, April 1911). 

 It has been found that the seed of 

 Hevea brasiliensis, which has been im- 

 ported from time to time for use in 

 Grenada, has shown very unsatisfactory 

 germinating power, and, in view of the 

 cost of the seed, it was considered ex- 

 pedient by Mr, G. G. Auchinleck, B. Sc., 

 Superintendent of Agriculture, to make 

 observation on seeds grown locally, for 

 the purpose of deciding as to what the 

 low percentage of germination might be 

 due. The results of Mr. Auchinleck's in- 

 vestigations have been presented by him 

 in the form of a report, from which the 

 following information is taken. They 

 show that experience in Grenada is 

 confirmatory of that which has been 

 described already from other parts of 

 the world. 



Mr. Auchinleck points out that the low 

 germinating power of imported seed is 

 obviously due to actual sterility of the 

 seeds, to their rapid deterioration after 

 maturity, or to both causes acting 

 at once. For the purpose of obtaining 

 information in regard to the suggested 

 deterioration, seeds from capsules which 

 had been opened just before dehiscence 

 took place were planted twenty-four 

 hours after the fruits had been plucked, 

 a few being kept, however, for three 

 days. The number of seeds collected 

 altogether was 975, and 160 of these were 

 set aside as being too light. That there 

 is a great difference in weight between 

 the heavy and light seeds is shown by 

 the fact that 100 of the former were 

 fouud to weigh 15 oz., while the weight 

 of the same number of light seeds was 

 only 6 oz. ; there was, however; no 

 observable difference in size between the 

 two kinds. 



In the continuation of the experiment, 

 all the light seeds were planted in a bed, 

 while of the heavy, eighty were sown at 

 stake and seventy-five in pots. None of 

 the light seeds germinated ; of the heavy, 

 nineteen of those at stake, and thirteen 

 in pots, gave sprouts. These results 

 appear to justify the rejection of light 

 seeds when those of Hevea are being 

 selected for planting. 



Observations on the rapidity with 

 which the seeds lose weight, together 

 with the consideration that from two 

 weeks to several months are required 

 for germination, led to the supposition 



that the rate at which heavy seeds be- 

 come lighter in the soil might result in a 

 serious diminution of their power to 

 germinate, before the young plant has 

 had time to pierce the hard seed coat. 

 This led to the following experiment, 

 undertaken to find how quickly heavy 

 Hevea seeds may lose weight. 



Por the purpose, ten heavy seeds were 

 packed in thoroughly dried charcoal, in 

 a flask ; while ten others were placed in a 

 flask open to the air. Each lot was taken 

 periodically from its flask, at the same 

 time, and weighed, with the following 

 results : — 



Day of 



Seeds 



Seeds in 



weighing. 



in air. 



charcoal. 



grams. 



grams. 



1st. 



48' 8 



49'0 



5th 



48-5 



43-5 



9th 



47-0 



405 



15th 



45-5 



38-7 



20th 



44.4 



38-0 



25th 



43 '0 



37-5 



30th 



41'8 



37-2 



42nd 



39-0 



37-0 



49 th 



38-0 



37 "0 



54 th 



37-5 



37 '0 



Calculation of the results shows that 

 in two weeks the seeds kept in air had 

 lost 6 percent, of their weight and those 

 in dry charcoal 20 per cent., the latter 

 being about the extreme limit of 

 desiccation ; the light seeds took fifty 

 days to reach this. 



Further observations, made for the 

 purpose of ascertaining the cause of the 

 decrease in weight, gave negative indica- 

 tions that this is due to the loss of 

 water ; and it is thought that it takes 

 place on account of the presence of a 

 definite ferment in the seed. 



The fact that the trials were com- 

 menced late in the bearing season make 

 it impossible to ascertain if the poor 

 germinating power is the indirect result 

 of some imperfection in the flower, or 

 irregularity in fertilization. It was 

 noted, however, that the embryos of all 

 the seeds examined appeared to be 

 normal, and there was the interesting 

 observation that, out of about 320 

 capsules, all were trilocular and three 

 seeded, except two, which possessed four 

 loculi and four seeds. The seeds in the 

 abnormal capsules were subjected to a 

 germination test, and three out of the 

 eight gave sprouts. Attention is drawn 

 to the faint possibility that a tendency 

 toward irregularity in the floral organs 

 of Hevea brasiliensis is indicated, with 

 the consequent production of a low 



