20 
BULLETIN 3 4, PORTO RICO EXPERIMENT STATION 
Nuts 
/eo 
/60 
JUO 
IZO 
/oo 
in size in five plats in the fourth period. The average nut size in 
plat No. 3 varied from one period to another by only 0.04 inch. The 
next smallest difference, 0.06 inch, occurred in both the check plat 
No. 4 and in the completely fertilized plat No. 5. The greatest dif- 
ference, 0.18 inch, was in plat No. 1. No correlation was shown 
between nut size and fertilization. The influence of fertilizer on nut 
size, if operative at all, was insignificant. 
SUMMARY AND CONCLUSIONS 
Individual production records were obtained on 490 coconut palms 
producing 145,850 nuts in the course of the experiments. The palms 
were in three different localities, 
and each group represented a dis- 
tinct stage in the life of the 
tree. The production record on the 
youngest palms extended to 15 
years after planting and for the 
older groups through more than 
6 and 11 years, respectively. The 
data collected furnish information 
on the bearing habits of the coconut 
palm, which should be of value 
wherever the coconut is grown. 
The palms in the youngest group 
appeared to have benefited from 
fertilization inasmuch as all the 
treated plats considerably surpassed 
the untreated plat in production. 
However, in view of the contradic- 
tions displayed in the other plats, 
and also of the existence of but a 
single check plat, it may be ques- 
tioned whether the inferiority of 
the latter was due mainly to the 
lack of fertilization or to an aggre- 
gation of naturally low-yielding 
palms within it. The results from 
plats fertilized with nitrogen, phos- 
phoric acid, and potash in combi- 
nations of two or more elements 
were so contradictory as to lead to 
the conclusion that the differences 
between plats resulted principally 
from factors other than fertilizer treatment. It is illogical to assume 
that the application of nitrogen and phosphoric acid, the fertilizer 
treatment given to the most productive plat, resulted in significant 
increases when similar and even twice the amounts of nitrogen and 
phosphoric acid in combination with potash gave increases only a 
little more than half as great. 
In the fertilizer tests with palms of intermediate age the yield 
of low-production palms increased decidedly under fertilization, 
whereas high-production palms showed little change in productivity. 
Th>s.e** 
Pigure 13. — Average production per 
palm in 40 harvests at Boquillas plan- 
tation, palms grouped according to 
elevation above sea level 
